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Who are you? | I am Clara an AI Java chatbot created to help you learn Java. Ask me anything Java related and I'll do my best to answer it. |
What is Java? | Java is a programming language and a platform. Java is a high level, robust, object-oriented and secure programming language.
Java was developed by Sun Microsystems (which is now the subsidiary of Oracle) in the year 1995. James Gosling is known as the father of Java. Before Java, its name was Oak. Since Oak was already a registered company, so James Gosling and his team changed the name from Oak to Java.
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Can you provide an example of Java Hello World program? | Let's have a quick look at Java programming example. A detailed description of Hello Java example is available in next page.
Simple.java:
class Simple{
public static void main(String args[]){
System.out.println("Hello Java");
}
}
|
Could you provide examples of applications or platforms that leverage Java for their development? | According to Sun, 3 billion devices run Java. There are many devices where Java is currently used. Some of them are as follows:
- Desktop Applications such as acrobat reader, media player, antivirus, etc.
- Web Applications such as irctc.co.in, javatpoint.com, etc.
- Enterprise Applications such as banking applications.
- Mobile
- Embedded System
- Smart Card
- Robotics
- Games, etc.
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What are the Types of Java Applications? | There are mainly 4 types of applications that can be created using Java programming:
1) Standalone Application
Standalone applications are also known as desktop applications or window-based applications. These are traditional software that we need to install on every machine.
Examples of standalone applications are Media player, antivirus, etc. AWT and Swing are used in Java for creating standalone applications.
2) Web Application
An application that runs on the server side and creates a dynamic page is called a web application. Currently, Servlet, JSP, Struts, Spring, Hibernate, JSF, etc. technologies are used for creating web applications in Java.
3) Enterprise Application
An application that is distributed in nature, such as banking applications, etc. is called an enterprise application. It has advantages like high-level security, load balancing, and clustering. In Java, EJB is used for creating enterprise applications.
4) Mobile Application
An application which is created for mobile devices is called a mobile application. Currently, Android and Java ME are used for creating mobile applications.
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What are the Java Platforms / Editions ? | There are 4 platforms or editions of Java:
1) Java SE (Java Standard Edition)
It is a Java programming platform. It includes Java programming APIs such as java.lang, java.io, java.net, java.util, java.sql, java.math etc. It includes core topics like OOPs, String, Regex, Exception, Inner classes, Multithreading, I/O Stream, Networking, AWT, Swing, Reflection, Collection, etc.
2) Java EE (Java Enterprise Edition)
It is an enterprise platform that is mainly used to develop web and enterprise applications. It is built on top of the Java SE platform. It includes topics like Servlet, JSP, Web Services, EJB, JPA, etc.
3) Java ME (Java Micro Edition)
It is a micro platform that is dedicated to mobile applications.
4) JavaFX
It is used to develop rich internet applications. It uses a lightweight user interface API.
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Can you elaborate the History of Java ? | The history of Java is very interesting. Java was originally designed for interactive television, but it was too advanced technology for the digital cable television industry at the time. The history of Java starts with the Green Team. Java team members (also known as Green Team), initiated this project to develop a language for digital devices such as set-top boxes, televisions, etc. However, it was best suited for internet programming. Later, Java technology was incorporated by Netscape.
The principles for creating Java programming were "Simple, Robust, Portable, Platform-independent, Secured, High Performance, Multithreaded, Architecture Neutral, Object-Oriented, Interpreted, and Dynamic". Java was developed by James Gosling, who is known as the father of Java, in 1995. James Gosling and his team members started the project in the early '90s.
Currently, Java is used in internet programming, mobile devices, games, e-business solutions, etc. Following are given significant points that describe the history of Java.
1) James Gosling, Mike Sheridan, and Patrick Naughton initiated the Java language project in June 1991. The small team of sun engineers called Green Team.
2) Initially it was designed for small, embedded systems in electronic appliances like set-top boxes.
3) Firstly, it was called "Greentalk" by James Gosling, and the file extension was .gt.
4) After that, it was called Oak and was developed as a part of the Green project.
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Why Java was named as "Oak"? | 5) Why Oak? Oak is a symbol of strength and chosen as a national tree of many countries like the U.S.A., France, Germany, Romania, etc.
6) In 1995, Oak was renamed as "Java" because it was already a trademark by Oak Technologies.
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Why Java Programming named "Java"? | 7) Why had they chose the name Java for Java language? The team gathered to choose a new name. The suggested words were "dynamic", "revolutionary", "Silk", "jolt", "DNA", etc. They wanted something that reflected the essence of the technology: revolutionary, dynamic, lively, cool, unique, and easy to spell, and fun to say.
According to James Gosling, "Java was one of the top choices along with Silk". Since Java was so unique, most of the team members preferred Java than other names.
8) Java is an island in Indonesia where the first coffee was produced (called Java coffee). It is a kind of espresso bean. Java name was chosen by James Gosling while having a cup of coffee nearby his office.
9) Notice that Java is just a name, not an acronym.
10) Initially developed by James Gosling at Sun Microsystems (which is now a subsidiary of Oracle Corporation) and released in 1995.
11) In 1995, Time magazine called Java one of the Ten Best Products of 1995.
12) JDK 1.0 was released on January 23, 1996. After the first release of Java, there have been many additional features added to the language. Now Java is being used in Windows applications, Web applications, enterprise applications, mobile applications, cards, etc. Each new version adds new features in Java.
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Can you outline the evolution of Java versions from its initial release to the current stable release? | Many java versions have been released till now. The current stable release of Java is Java SE 10.
1) JDK Alpha and Beta (1995)
2) JDK 1.0 (23rd Jan 1996)
3) JDK 1.1 (19th Feb 1997)
4) J2SE 1.2 (8th Dec 1998)
5) J2SE 1.3 (8th May 2000)
6) J2SE 1.4 (6th Feb 2002)
7) J2SE 5.0 (30th Sep 2004)
8) Java SE 6 (11th Dec 2006)
9) Java SE 7 (28th July 2011)
10) Java SE 8 (18th Mar 2014)
11) Java SE 9 (21st Sep 2017)
12) Java SE 10 (20th Mar 2018)
13) Java SE 11 (September 2018)
14) Java SE 12 (March 2019)
15) Java SE 13 (September 2019)
16) Java SE 14 (Mar 2020)
17) Java SE 15 (September 2020)
18) Java SE 16 (Mar 2021)
19) Java SE 17 (September 2021)
20) Java SE 18 (to be released by March 2022)
Since Java SE 8 release, the Oracle corporation follows a pattern in which every even version is release in March month and an odd version released in September month.
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What are the Features of Java? | The primary objective of Java programming language creation was to make it portable, simple and secure programming language. Apart from this, there are also some excellent features which play an important role in the popularity of this language. The features of Java are also known as Java buzzwords.
A list of the most important features of the Java language is given below.
1) Simple
2) Object-Oriented
3) Portable
4) Platform independent
5) Secured
6) Robust
7) Architecture neutral
8) Interpreted
9) High Performance
10) Multithreaded
11) Distributed
12) Dynamic
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Is Java easy to learn? | Java is very easy to learn, and its syntax is simple, clean and easy to understand. According to Sun Microsystem, Java language is a simple programming language because:
-Java syntax is based on C++ (so easier for programmers to learn it after C++).
-Java has removed many complicated and rarely-used features, for example, explicit pointers, operator overloading, etc.
-There is no need to remove unreferenced objects because there is an Automatic Garbage Collection in Java. |
Is Java Object-oriented? | Java is an object-oriented programming language. Everything in Java is an object. Object-oriented means we organize our software as a combination of different types of objects that incorporate both data and behavior.
Object-oriented programming (OOPs) is a methodology that simplifies software development and maintenance by providing some rules.
Basic concepts of OOPs are:
1) Object
2) Class
3) Inheritance
4) Polymorphism
5) Abstraction
6) Encapsulation
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Is Java Platform Independent? | Java is platform independent because it is different from other languages like C, C++, etc. which are compiled into platform specific machines while Java is a write once, run anywhere language. A platform is the hardware or software environment in which a program runs.
There are two types of platforms software-based and hardware-based. Java provides a software-based platform.
The Java platform differs from most other platforms in the sense that it is a software-based platform that runs on top of other hardware-based platforms. It has two components:
1) Runtime Environment
2) API(Application Programming Interface)
Java code can be executed on multiple platforms, for example, Windows, Linux, Sun Solaris, Mac/OS, etc. Java code is compiled by the compiler and converted into bytecode. This bytecode is a platform-independent code because it can be run on multiple platforms, i.e., Write Once and Run Anywhere (WORA).
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Is Java Secured? | Java is best known for its security. With Java, we can develop virus-free systems. Java is secured because:
-No explicit pointer
-Java Programs run inside a virtual machine sandbox
-Classloader: Classloader in Java is a part of the Java Runtime Environment (JRE) which is used to load Java classes into the Java Virtual Machine dynamically. It adds security by separating the package for the classes of the local file system from those that are imported from network sources.
-Bytecode Verifier: It checks the code fragments for illegal code that can violate access rights to objects.
-Security Manager: It determines what resources a class can access such as reading and writing to the local disk.
Java language provides these securities by default. Some security can also be provided by an application developer explicitly through SSL, JAAS, Cryptography, etc.
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Is Java Robust? | The English mining of Robust is strong. Java is robust because:
-It uses strong memory management.
-There is a lack of pointers that avoids security problems.
-Java provides automatic garbage collection which runs on the Java Virtual Machine to get rid of objects which are not being used by a Java application anymore.
-There are exception handling and the type checking mechanism in Java. All these points make Java robust.
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Is Java Architecture-neutral? | Java is architecture neutral because there are no implementation dependent features, for example, the size of primitive types is fixed.
In C programming, int data type occupies 2 bytes of memory for 32-bit architecture and 4 bytes of memory for 64-bit architecture. However, it occupies 4 bytes of memory for both 32 and 64-bit architectures in Java.
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Is Java Portable? | Java is portable because it facilitates you to carry the Java bytecode to any platform. It doesn't require any implementation. |
What is the level of performance of Java? | Java is faster than other traditional interpreted programming languages because Java bytecode is "close" to native code. It is still a little bit slower than a compiled language (e.g., C++). Java is an interpreted language that is why it is slower than compiled languages, e.g., C, C++, etc. |
Is Java Distributed? | Java is distributed because it facilitates users to create distributed applications in Java. RMI and EJB are used for creating distributed applications. This feature of Java makes us able to access files by calling the methods from any machine on the internet. |
Is Java Multi-threaded? | A thread is like a separate program, executing concurrently. We can write Java programs that deal with many tasks at once by defining multiple threads. The main advantage of multi-threading is that it doesn't occupy memory for each thread. It shares a common memory area. Threads are important for multi-media, Web applications, etc. |
Is Java Dynamic? | Java is a dynamic language. It supports the dynamic loading of classes. It means classes are loaded on demand. It also supports functions from its native languages, i.e., C and C++.
Java supports dynamic compilation and automatic memory management (garbage collection).
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Can you compare C++ to Java? | There are many differences and similarities between the C++ programming language and Java. A list of top differences between C++ and Java are given below:
Platform-independent: C++ is platform-dependent while Java is platform-independent.
Mainly used for: C++ is mainly used for system programming while Java is mainly used for application programming. It is widely used in Windows-based, web-based, enterprise, and mobile applications.
Design Goal: C++ was designed for systems and applications programming. It was an extension of the C programming language while Java was designed and created as an interpreter for printing systems but later extended as a support network computing. It was designed to be easy to use and accessible to a broader audience.
Goto: C++ supports the goto statement while Java doesn't support the goto statement.
Multiple inheritance: C++ supports multiple inheritance while Java doesn't support multiple inheritance through class. It can be achieved by using interfaces in java.
Operator Overloading: C++ supports operator overloading while Java doesn't support operator overloading.
Pointers: C++ supports pointers. You can write a pointer program in C++ while Java supports pointer internally. However, you can't write the pointer program in java. It means java has restricted pointer support in java.
Compiler and Interpreter: C++ uses compiler only. C++ is compiled and run using the compiler which converts source code into machine code so, C++ is platform dependent while Java uses both compiler and interpreter. Java source code is converted into bytecode at compilation time. The interpreter executes this bytecode at runtime and produces output. Java is interpreted that is why it is platform-independent.
Call by Value and Call by reference: C++ supports both call by value and call by reference while Java supports call by value only. There is no call by reference in java.
Structure and Union: C++ supports structures and unions while Java doesn't support structures and unions.
Thread Support: C++ doesn't have built-in support for threads. It relies on third-party libraries for thread support while Java has built-in thread support.
Documentation comment: C++ doesn't support documentation comments while Java supports documentation comment (/** ... */) to create documentation for java source code.
Virtual Keyword: C++ supports virtual keyword so that we can decide whether or not to override a function. Java has no virtual keyword. We can override all non-static methods by default. In other words, non-static methods are virtual by default.
unsigned right shift >>> : C++ doesn't support >>> operator while Java supports unsigned right shift >>> operator that fills zero at the top for the negative numbers. For positive numbers, it works same like >> operator.
Inheritance Tree: C++ always creates a new inheritance tree while Java always uses a single inheritance tree because all classes are the child of the Object class in Java. The Object class is the root of the inheritance tree in java.
Hardware: C++ is nearer to hardware while Java is not so interactive with hardware.
Object-oriented: C++ is an object-oriented language. However, in the C language, a single root hierarchy is not possible while Java is also an object-oriented language. However, everything (except fundamental types) is an object in Java. It is a single root hierarchy as everything gets derived from java.lang.Object.
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Can you provide a Java Hello World Example? | The requirement for Java Hello World Example
For executing any Java program, the following software or application must be properly installed.
Install the JDK if you don't have installed it, download the JDK and install it.
Set path of the jdk/bin directory. http://www.javatpoint.com/how-to-set-path-in-java
Create the Java program
Compile and run the Java program
Creating Hello World Example
Let's create the hello java program:
class Simple{
public static void main(String args[]){
System.out.println("Hello Java");
}
}
Save the above file as Simple.java.
To compile:
javac Simple.java
To execute:
java Simple
Output:
Hello Java
Compilation Flow:
When we compile Java program using javac tool, the Java compiler converts the source code into byte code.
Parameters used in First Java Program
Let's see what is the meaning of class, public, static, void, main, String[], System.out.println().
-class keyword is used to declare a class in Java.
-public keyword is an access modifier that represents visibility. It means it is visible to all.
-static is a keyword. If we declare any method as static, it is known as the static method. The core advantage of the static method is that there is no need to create an object to invoke the static method. The main() method is executed by the JVM, so it doesn't require creating an object to invoke the main() method. So, it saves memory.
-void is the return type of the method. It means it doesn't return any value.
-main represents the starting point of the program.
-String[] args or String args[] is used for command line argument. We will discuss it in coming section.
-System.out.println() is used to print statement. Here, System is a class, out is an object of the PrintStream class, println() is a method of the PrintStream class. We will discuss the internal working of System.out.println() statement in the coming section.
To write the simple program, you need to open notepad by start menu -> All Programs -> Accessories -> Notepad and write a simple program:
Class simple{
Public static void main(String args[]){
System.out.println(“Hello Java”);
}
}
write the simple program of Java in notepad and saved it as Simple.java. In order to compile and run the above program, you need to open the command prompt by start menu -> All Programs -> Accessories -> command prompt.
To compile and run the above program, go to your current directory first; my current directory is c:\new. Write here:
To compile:
javac Simple.java
To execute:
java Simple
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In how many ways we can write a Java program? | There are many ways to write a Java program. The modifications that can be done in a Java program are given below:
1) By changing the sequence of the modifiers, method prototype is not changed in Java.
Let's see the simple code of the main method.
static public void main(String args[])
2) The subscript notation in the Java array can be used after type, before the variable or after the variable.
Let's see the different codes to write the main method.
public static void main(String[] args)
public static void main(String []args)
public static void main(String args[])
3) You can provide var-args support to the main() method by passing 3 ellipses (dots)
Let's see the simple code of using var-args in the main() method. We will learn about var-args later in the Java New Features chapter.
public static void main(String... args)
4) Having a semicolon at the end of class is optional in Java.
Let's see the simple code.
class A{
static public void main(String... args){
System.out.println("hello java4");
}
};
|
What are the valid Java main() method signatures? | public static void main(String[] args)
public static void main(String []args)
public static void main(String args[])
public static void main(String... args)
static public void main(String[] args)
public static final void main(String[] args)
final public static void main(String[] args)
final strictfp public static void main(String[] args)
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What are the invalid Java main() method signatures? | public void main(String[] args)
static void main(String[] args)
public void static main(String[] args)
abstract public static void main(String[] args)
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Resolving an error "javac is not recognized as an internal or external command"? | If there occurs a problem like displayed in the below figure, you need to set a path. Since DOS doesn't recognize javac and java as internal or external command. To overcome this problem, we need to set a path. The path is not required in a case where you save your program inside the JDK/bin directory. However, it is an excellent approach to set the path. |
What happens at compile time? | At compile time, the Java file is compiled by Java Compiler (It does not interact with OS) and converts the Java code into bytecode.
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What happens at runtime? | At runtime, the following steps are performed:
Class File →Classloader→Bytecode Verified→Interpreter→Runtime→Hardware
Classloader: It is the subsystem of JVM that is used to load class files.
Bytecode Verifier: Checks the code fragments for illegal code that can violate access rights to objects.
Interpreter: Read bytecode stream then execute the instructions.
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Can you save a Java source file by another name than the class name? | Yes, if the class is not public.
To compile:
javac Hard.java
To execute:
java Simple
Observe that, we have compiled the code with file name but running the program with class name. Therefore, we can save a Java program other than class name.
|
How to set path in Java? | The path is required to be set for using tools such as javac, java, etc.
If you are saving the Java source file inside the JDK/bin directory, the path is not required to be set because all the tools will be available in the current directory.
However, if you have your Java file outside the JDK/bin folder, it is necessary to set the path of JDK.
1.Temporary
2.Permanent |
How to set the Temporary Path of JDK in Windows? | To set the temporary path of JDK, you need to follow the following steps:
-Open the command prompt
-Copy the path of the JDK/bin directory
-Write in command prompt: set path=copied_path |
What are the Difference between JDK, JRE, and JVM? | We must understand the differences between JDK, JRE, and JVM before proceeding further to Java. See the brief overview of JVM here.
If you want to get the detailed knowledge of Java Virtual Machine, move to the next page. Firstly, let's see the differences between the JDK, JRE, and JVM.
JVM (Java Virtual Machine) is an abstract machine. It is called a virtual machine because it doesn't physically exist. It is a specification that provides a runtime environment in which Java bytecode can be executed. It can also run those programs which are written in other languages and compiled to Java bytecode.
JVMs are available for many hardware and software platforms. JVM, JRE, and JDK are platform dependent because the configuration of each OS is different from each other. However, Java is platform independent. There are three notions of the JVM: specification, implementation, and instance.
The JVM performs the following main tasks:
-Loads code
-Verifies code
-Executes code
-Provides runtime environment
JRE is an acronym for Java Runtime Environment. It is also written as Java RTE. The Java Runtime Environment is a set of software tools which are used for developing Java applications. It is used to provide the runtime environment. It is the implementation of JVM. It physically exists. It contains a set of libraries + other files that JVM uses at runtime.
JDK is an acronym for Java Development Kit. The Java Development Kit (JDK) is a software development environment which is used to develop Java applications and applets. It physically exists. It contains JRE + development tools.
JDK is an implementation of any one of the below given Java Platforms released by Oracle Corporation:
-Standard Edition Java Platform
-Enterprise Edition Java Platform
-Micro Edition Java Platform
The JDK contains a private Java Virtual Machine (JVM) and a few other resources such as an interpreter/loader (java), a compiler (javac), an archiver (jar), a documentation generator (Javadoc), etc. to complete the development of a Java Application. |
What is JVM (Java Virtual Machine)? | JVM (Java Virtual Machine) is an abstract machine. It is a specification that provides runtime environment in which java bytecode can be executed.
JVMs are available for many hardware and software platforms (i.e. JVM is platform dependent).
1.A specification where working of Java Virtual Machine is specified. But implementation provider is independent to choose the algorithm. Its implementation has been provided by Oracle and other companies.
2.An implementation Its implementation is known as JRE (Java Runtime Environment).
3.Runtime Instance Whenever you write java command on the command prompt to run the java class, an instance of JVM is created.
The JVM performs following operation:
-Loads code
-Verifies code
-Executes code
-Provides runtime environment
JVM provides definitions for the:
-Memory area
-Class file format
-Register set
Garbage-collected heap
Fatal error reporting etc. |
Can you help me understand JVM Architecture? | Let's understand the internal architecture of JVM. It contains classloader, memory area, execution engine etc.
1) Classloader
Classloader is a subsystem of JVM which is used to load class files. Whenever we run the java program, it is loaded first by the classloader. There are three built-in classloaders in Java.
Bootstrap ClassLoader: This is the first classloader which is the super class of Extension classloader. It loads the rt.jar file which contains all class files of Java Standard Edition like java.lang package classes, java.net package classes, java.util package classes, java.io package classes, java.sql package classes etc.
Extension ClassLoader: This is the child classloader of Bootstrap and parent classloader of System classloader. It loades the jar files located inside $JAVA_HOME/jre/lib/ext directory.
System/Application ClassLoader: This is the child classloader of Extension classloader. It loads the classfiles from classpath. By default, classpath is set to current directory. You can change the classpath using "-cp" or "-classpath" switch. It is also known as Application classloader.
//Let's see an example to print the classloader name
public class ClassLoaderExample
{
public static void main(String[] args)
{
// Let's print the classloader name of current class.
//Application/System classloader will load this class
Class c=ClassLoaderExample.class;
System.out.println(c.getClassLoader());
//If we print the classloader name of String, it will print null because it is an
//in-built class which is found in rt.jar, so it is loaded by Bootstrap classloader
System.out.println(String.class.getClassLoader());
}
}
Output:
sun.misc.Launcher$AppClassLoader@4e0e2f2a
null
These are the internal classloaders provided by Java. If you want to create your own classloader, you need to extend the ClassLoader class.
2) Class(Method) Area
Class(Method) Area stores per-class structures such as the runtime constant pool, field and method data, the code for methods.
3) Heap
It is the runtime data area in which objects are allocated.
4) Stack
Java Stack stores frames. It holds local variables and partial results, and plays a part in method invocation and return.
Each thread has a private JVM stack, created at the same time as thread.
A new frame is created each time a method is invoked. A frame is destroyed when its method invocation completes.
5) Program Counter Register
PC (program counter) register contains the address of the Java virtual machine instruction currently being executed.
6) Native Method Stack
It contains all the native methods used in the application.
7) Execution Engine
It contains:
A virtual processor
Interpreter: Read bytecode stream then execute the instructions.
Just-In-Time(JIT) compiler: It is used to improve the performance. JIT compiles parts of the byte code that have similar functionality at the same time, and hence reduces the amount of time needed for compilation. Here, the term "compiler" refers to a translator from the instruction set of a Java virtual machine (JVM) to the instruction set of a specific CPU.
8) Java Native Interface
Java Native Interface (JNI) is a framework which provides an interface to communicate with another application written in another language like C, C++, Assembly etc. Java uses JNI framework to send output to the Console or interact with OS libraries.
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What is Java Variables? | A variable is a container which holds the value while the Java program is executed. A variable is assigned with a data type.
Variable is a name of memory location. There are three types of variables in java: local, instance and static.
There are two types of data types in Java: primitive and non-primitive.
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What are the Types of Variables in Java? | There are three types of variables in Java:
-local variable
-instance variable
-static variable |
Can you provide an Example to understand the types of variables in java? | 1) Local Variable
A variable declared inside the body of the method is called local variable. You can use this variable only within that method and the other methods in the class aren't even aware that the variable exists.
A local variable cannot be defined with "static" keyword.
2) Instance Variable
A variable declared inside the class but outside the body of the method, is called an instance variable. It is not declared as static.
It is called an instance variable because its value is instance-specific and is not shared among instances.
3) Static variable
A variable that is declared as static is called a static variable. It cannot be local. You can create a single copy of the static variable and share it among all the instances of the class. Memory allocation for static variables happens only once when the class is loaded in the memory. |
Can you provide Java Variable Example: Add Two Numbers? | public class Simple{
public static void main(String[] args){
int a=10;
int b=10;
int c=a+b;
System.out.println(c);
}
}
Output: 20 |
Can you provide Java Variable Example: Widening? | public class Simple{
public static void main(String[] args){
int a=10;
float f=a;
System.out.println(a);
System.out.println(f);
}}
Output: 10
10.0 |
Can you provide Java Variable Example: Narrowing (Typecasting)? | public class Simple{
public static void main(String[] args){
float f=10.5f;
//int a=f;//Compile time error
int a=(int)f;
System.out.println(f);
System.out.println(a);
}}
Output: 10.5
10 |
Can you provide Java Variable Example: Overflow? | class Simple{
public static void main(String[] args){
//Overflow
int a=130;
byte b=(byte)a;
System.out.println(a);
System.out.println(b);
}}
Output: 130
-126 |
Can you provide Java Variable Example: Adding Lower Type? | class Simple{
public static void main(String[] args){
byte a=10;
byte b=10;
//byte c=a+b;//Compile Time Error: because a+b=20 will be int
byte c=(byte)(a+b);
System.out.println(c);
}}
Output: 20 |
What is Data Types in Java? | Data types specify the different sizes and values that can be stored in the variable. There are two types of data types in Java:
1.Primitive data types: The primitive data types include boolean, char, byte, short, int, long, float and double.
2.Non-primitive data types: The non-primitive data types include Classes, Interfaces, and Arrays. |
What is Java Primitive Data Types? | In Java language, primitive data types are the building blocks of data manipulation. These are the most basic data types available in Java language.
There are 8 types of primitive data types:
-boolean data type
-byte data type
-char data type
-short data type
-int data type
-long data type
-float data type
-double data type |
Why char uses 2 byte in java and what is \u0000 ? | It is because java uses Unicode system not ASCII code system. The \u0000 is the lowest range of Unicode system. To get detail explanation about Unicode visit next page.
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Why java uses Unicode System? | Before Unicode, there were many language standards:
ASCII (American Standard Code for Information Interchange) for the United States.
ISO 8859-1 for Western European Language.
KOI-8 for Russian.
GB18030 and BIG-5 for chinese, and so on. |
What is Operators in Java? | Operator in Java is a symbol that is used to perform operations. For example: +, -, *, / etc.
There are many types of operators in Java which are given below:
-Unary Operator,
-Arithmetic Operator,
-Shift Operator,
-Relational Operator,
-Bitwise Operator,
-Logical Operator,
-Ternary Operator and
-Assignment Operator. |
What are the Java Operator Precedence? | Java Operator Precedence
Operator type: Unary
Category: postfix
Precedence: expr++ expr--
Category: prefix
Precedence: ++expr --expr +expr -expr ~ !
Operator type: Arithmetic
Category: multiplicative
Precedence: * / %
Category: additive
Precedence: + -
Operator type: Shift
Category: shift
Precedence: << >> >>>
Operator type: Relational
Category: comparison
Precedence: < > <= >= instanceof
Category: equality
Precedence: == !=
Operator type: Bitwise
Category: bitwise AND
Precedence: &
Category: bitwise exclusive OR
Precedence: ^
Category: bitwise inclusive OR
Precedence: |
Operator type: Logical
Category: logical AND
Precedence: &&
Category: logical OR
Precedence: ||
Operator type: Ternary
Category: ternary
Precedence: ? :
Operator type: Assignment
Category: assignment
Precedence: = += -= *= /= %= &= ^= |= <<= >>= >>>=
|
What is Java Unary Operator? | The Java unary operators require only one operand. Unary operators are used to perform various operations i.e.:
-incrementing/decrementing a value by one
-negating an expression
-inverting the value of a boolean |
Can you provide an example of Java Unary Operator? | public class OperatorExample{
public static void main(String args[]){
int x=10;
System.out.println(x++);//10 (11)
System.out.println(++x);//12
System.out.println(x--);//12 (11)
System.out.println(--x);//10
}}
Output:
10
12
12
10 |
Can you provide an example of Java Unary Operator ++ and -- ? | public class OperatorExample{
public static void main(String args[]){
int a=10;
int b=10;
System.out.println(a++ + ++a);//10+12=22
System.out.println(b++ + b++);//10+11=21
}}
Output:
22
21 |
Can you provide an example of Java Unary Operator ~ and ! ? | public class OperatorExample{
public static void main(String args[]){
int a=10;
int b=-10;
boolean c=true;
boolean d=false;
System.out.println(~a);//-11 (minus of total positive value which starts from 0)
System.out.println(~b);//9 (positive of total minus, positive starts from 0)
System.out.println(!c);//false (opposite of boolean value)
System.out.println(!d);//true
}}
Output:
-11
9
false
true |
What is Java Arithmetic Operators? | Java arithmetic operators are used to perform addition, subtraction, multiplication, and division. They act as basic mathematical operations. |
Can you provide an example of Java Arithmetic Operator? | public class OperatorExample{
public static void main(String args[]){
int a=10;
int b=5;
System.out.println(a+b);//15
System.out.println(a-b);//5
System.out.println(a*b);//50
System.out.println(a/b);//2
System.out.println(a%b);//0
}}
Output:
15
5
50
2
0 |
Can you provide an example of Java Arithmetic Operator Expression? | public class OperatorExample{
public static void main(String args[]){
System.out.println(10*10/5+3-1*4/2);
}}
Output:
21 |
What is Java Left Shift Operator? | The Java left shift operator << is used to shift all of the bits in a value to the left side of a specified number of times.
|
Can you provide an example of Java Left Shift Operator Example ? | public class OperatorExample{
public static void main(String args[]){
System.out.println(10<<2);//10*2^2=10*4=40
System.out.println(10<<3);//10*2^3=10*8=80
System.out.println(20<<2);//20*2^2=20*4=80
System.out.println(15<<4);//15*2^4=15*16=240
}}
Output:
40
80
80
240 |
What is Java Right Shift Operator? | The Java right shift operator >> is used to move the value of the left operand to right by the number of bits specified by the right operand. |
Can you provide an example of Java Right Shift Operator? | public OperatorExample{
public static void main(String args[]){
System.out.println(10>>2);//10/2^2=10/4=2
System.out.println(20>>2);//20/2^2=20/4=5
System.out.println(20>>3);//20/2^3=20/8=2
}}
Output:
2
5
2 |
Can you provide an example of Java Shift Operator >> vs >>> ? | public class OperatorExample{
public static void main(String args[]){
//For positive number, >> and >>> works same
System.out.println(20>>2);
System.out.println(20>>>2);
//For negative number, >>> changes parity bit (MSB) to 0
System.out.println(-20>>2);
System.out.println(-20>>>2);
}}
Output:
5
5
-5
1073741819 |
Can you provide an example of Java AND Operator Logical && and Bitwise &? | The logical && operator doesn't check the second condition if the first condition is false. It checks the second condition only if the first one is true.
The bitwise & operator always checks both conditions whether first condition is true or false.
public class OperatorExample{
public static void main(String args[]){
int a=10;
int b=5;
int c=20;
System.out.println(a<b&&a<c);//false && true = false
System.out.println(a<b&a<c);//false & true = false
}}
Output:
false
false |
Can you provide an example of Java AND Operator Example: Logical && vs Bitwise & ? | public class OperatorExample{
public static void main(String args[]){
int a=10;
int b=5;
int c=20;
System.out.println(a<b&&a++<c);//false && true = false
System.out.println(a);//10 because second condition is not checked
System.out.println(a<b&a++<c);//false && true = false
System.out.println(a);//11 because second condition is checked
}}
Output:
false
10
false
11 |
Can you provide an example of Java OR Operator Logical || and Bitwise | ? | The logical || operator doesn't check the second condition if the first condition is true. It checks the second condition only if the first one is false.
The bitwise | operator always checks both conditions whether first condition is true or false.
public class OperatorExample{
public static void main(String args[]){
int a=10;
int b=5;
int c=20;
System.out.println(a>b||a<c);//true || true = true
System.out.println(a>b|a<c);//true | true = true
//|| vs |
System.out.println(a>b||a++<c);//true || true = true
System.out.println(a);//10 because second condition is not checked
System.out.println(a>b|a++<c);//true | true = true
System.out.println(a);//11 because second condition is checked
}}
Output:
true
true
true
10
true
11 |
What is Java Ternary Operator? | Java Ternary operator is used as one line replacement for if-then-else statement and used a lot in Java programming. It is the only conditional operator which takes three operands. |
Can you provide an example of Java Ternary Operator? | public class OperatorExample{
public static void main(String args[]){
int a=10;
int b=5;
int min=(a<b)?a:b;
System.out.println(min);
}}
Output:
5
public class OperatorExample{
public static void main(String args[]){
int a=2;
int b=5;
int min=(a<b)?a:b;
System.out.println(min);
}}
Output:
2 |
What is Java Assignment Operator? | Java assignment operator is one of the most common operators. It is used to assign the value on its right to the operand on its left.
|
Can you provide an example of Java Assignment Operator Example | public class OperatorExample{
public static void main(String args[]){
int a=10;
int b=20;
a+=4;//a=a+4 (a=10+4)
b-=4;//b=b-4 (b=20-4)
System.out.println(a);
System.out.println(b);
}}
Output:
14
16
public class OperatorExample{
public static void main(String[] args){
int a=10;
a+=3;//10+3
System.out.println(a);
a-=4;//13-4
System.out.println(a);
a*=2;//9*2
System.out.println(a);
a/=2;//18/2
System.out.println(a);
}}
Output:
13
9
18
9
|
Can you provide an example of Java Assignment Operator Adding short | public class OperatorExample{
public static void main(String args[]){
short a=10;
short b=10;
//a+=b;//a=a+b internally so fine
a=a+b;//Compile time error because 10+10=20 now int
System.out.println(a);
}}
Output:
Compile time error
After type cast:
public class OperatorExample{
public static void main(String args[]){
short a=10;
short b=10;
a=(short)(a+b);//20 which is int now converted to short
System.out.println(a);
}}
Output:
20
|
What is Java Keywords? | Java keywords are also known as reserved words. Keywords are particular words that act as a key to a code. These are predefined words by Java so they cannot be used as a variable or object name or class name.
|
Can you provide the list of Java keywords? | A list of Java keywords or reserved words are given below:
1) abstract: Java abstract keyword is used to declare an abstract class. An abstract class can provide the implementation of the interface. It can have abstract and non-abstract methods.
2) boolean: Java boolean keyword is used to declare a variable as a boolean type. It can hold True and False values only.
3) break: Java break keyword is used to break the loop or switch statement. It breaks the current flow of the program at specified conditions.
4) byte: Java byte keyword is used to declare a variable that can hold 8-bit data values.
5) case: Java case keyword is used with the switch statements to mark blocks of text.
6) catch: Java catch keyword is used to catch the exceptions generated by try statements. It must be used after the try block only.
7) char: Java char keyword is used to declare a variable that can hold unsigned 16-bit Unicode characters
8) class: Java class keyword is used to declare a class.
9) continue: Java continue keyword is used to continue the loop. It continues the current flow of the program and skips the remaining code at the specified condition.
10) default: Java default keyword is used to specify the default block of code in a switch statement.
11) do: Java do keyword is used in the control statement to declare a loop. It can iterate a part of the program several times.
12) double: Java double keyword is used to declare a variable that can hold 64-bit floating-point number.
13) else: Java else keyword is used to indicate the alternative branches in an if statement.
14) enum: Java enum keyword is used to define a fixed set of constants. Enum constructors are always private or default.
15) extends: Java extends keyword is used to indicate that a class is derived from another class or interface.
16) final: Java final keyword is used to indicate that a variable holds a constant value. It is used with a variable. It is used to restrict the user from updating the value of the variable.
17) finally: Java finally keyword indicates a block of code in a try-catch structure. This block is always executed whether an exception is handled or not.
18) float: Java float keyword is used to declare a variable that can hold a 32-bit floating-point number.
19) for: Java for keyword is used to start a for loop. It is used to execute a set of instructions/functions repeatedly when some condition becomes true. If the number of iteration is fixed, it is recommended to use for loop.
20) if: Java if keyword tests the condition. It executes the if block if the condition is true.
21) implements: Java implements keyword is used to implement an interface.
22) import: Java import keyword makes classes and interfaces available and accessible to the current source code.
23) instanceof: Java instanceof keyword is used to test whether the object is an instance of the specified class or implements an interface.
24) int: Java int keyword is used to declare a variable that can hold a 32-bit signed integer.
25) interface: Java interface keyword is used to declare an interface. It can have only abstract methods.
26) long: Java long keyword is used to declare a variable that can hold a 64-bit integer.
27) native: Java native keyword is used to specify that a method is implemented in native code using JNI (Java Native Interface).
28) new: Java new keyword is used to create new objects.
29) null: Java null keyword is used to indicate that a reference does not refer to anything. It removes the garbage value.
30) package: Java package keyword is used to declare a Java package that includes the classes.
31) private: Java private keyword is an access modifier. It is used to indicate that a method or variable may be accessed only in the class in which it is declared.
32) protected: Java protected keyword is an access modifier. It can be accessible within the package and outside the package but through inheritance only. It can't be applied with the class.
33) public: Java public keyword is an access modifier. It is used to indicate that an item is accessible anywhere. It has the widest scope among all other modifiers.
34) return: Java return keyword is used to return from a method when its execution is complete.
35) short: Java short keyword is used to declare a variable that can hold a 16-bit integer.
36) static: Java static keyword is used to indicate that a variable or method is a class method. The static keyword in Java is mainly used for memory management.
37) strictfp: Java strictfp is used to restrict the floating-point calculations to ensure portability.
38) super: Java super keyword is a reference variable that is used to refer to parent class objects. It can be used to invoke the immediate parent class method.
39) switch: The Java switch keyword contains a switch statement that executes code based on test value. The switch statement tests the equality of a variable against multiple values.
40) synchronized: Java synchronized keyword is used to specify the critical sections or methods in multithreaded code.
41) this: Java this keyword can be used to refer the current object in a method or constructor.
42) throw: The Java throw keyword is used to explicitly throw an exception. The throw keyword is mainly used to throw custom exceptions. It is followed by an instance.
43) throws: The Java throws keyword is used to declare an exception. Checked exceptions can be propagated with throws.
44) transient: Java transient keyword is used in serialization. If you define any data member as transient, it will not be serialized.
45) try: Java try keyword is used to start a block of code that will be tested for exceptions. The try block must be followed by either catch or finally block.
46) void: Java void keyword is used to specify that a method does not have a return value.
47) volatile: Java volatile keyword is used to indicate that a variable may change asynchronously.
48) while: Java while keyword is used to start a while loop. This loop iterates a part of the program several times. If the number of iteration is not fixed, it is recommended to use the while loop.
|
What is Java Control Statements or Control Flow in Java? | Java compiler executes the code from top to bottom. The statements in the code are executed according to the order in which they appear. However, Java provides statements that can be used to control the flow of Java code. Such statements are called control flow statements. It is one of the fundamental features of Java, which provides a smooth flow of program.
Java provides three types of control flow statements.
Decision Making statements
if statements
switch statement
Loop statements
do while loop
while loop
for loop
for-each loop
Jump statements
break statement
continue statement |
What is Decision-Making statements in Java? | As the name suggests, decision-making statements decide which statement to execute and when. Decision-making statements evaluate the Boolean expression and control the program flow depending upon the result of the condition provided. There are two types of decision-making statements in Java, i.e., If statement and switch statement. |
What is If Statement in Java? | In Java, the "if" statement is used to evaluate a condition. The control of the program is diverted depending upon the specific condition. The condition of the If statement gives a Boolean value, either true or false. In Java, there are four types of if-statements given below.
1.Simple if statement
2.if-else statement
3.if-else-if ladder
4.Nested if-statement |
Can you provide an example of Simple if statement in Java? | It is the most basic statement among all control flow statements in Java. It evaluates a Boolean expression and enables the program to enter a block of code if the expression evaluates to true.
Syntax of if statement is given below.
if(condition) {
statement 1; //executes when condition is true
}
public class Student {
public static void main(String[] args) {
int x = 10;
int y = 12;
if(x+y > 20) {
System.out.println("x + y is greater than 20");
}
}
}
Output:
x + y is greater than 20 |
Can you provide an example of if-else statement in Java? | The if-else statement is an extension to the if-statement, which uses another block of code, i.e., else block. The else block is executed if the condition of the if-block is evaluated as false.
Syntax:
if(condition) {
statement 1; //executes when condition is true
}
else{
statement 2; //executes when condition is false
}
public class Student {
public static void main(String[] args) {
int x = 10;
int y = 12;
if(x+y < 10) {
System.out.println("x + y is less than 10");
} else {
System.out.println("x + y is greater than 20");
}
}
}
Output:
x + y is greater than 20 |
What is if-else-if ladder in Java?
| The if-else-if statement contains the if-statement followed by multiple else-if statements. In other words, we can say that it is the chain of if-else statements that create a decision tree where the program may enter in the block of code where the condition is true. We can also define an else statement at the end of the chain.
Syntax of if-else-if statement is given below.
if(condition 1) {
statement 1; //executes when condition 1 is true
}
else if(condition 2) {
statement 2; //executes when condition 2 is true
}
else {
statement 2; //executes when all the conditions are false
}
public class Student {
public static void main(String[] args) {
String city = "Delhi";
if(city == "Meerut") {
System.out.println("city is meerut");
}else if (city == "Noida") {
System.out.println("city is noida");
}else if(city == "Agra") {
System.out.println("city is agra");
}else {
System.out.println(city);
}
}
}
Output:
Delhipublic class Student {
public static void main(String[] args) {
String city = "Delhi";
if(city == "Meerut") {
System.out.println("city is meerut");
}else if (city == "Noida") {
System.out.println("city is noida");
}else if(city == "Agra") {
System.out.println("city is agra");
}else {
System.out.println(city);
}
}
}
Output:
Delhi |
What is Nested if-statement in Java? | In nested if-statements, the if statement can contain a if or if-else statement inside another if or else-if statement.
Syntax of Nested if-statement is given below.
if(condition 1) {
statement 1; //executes when condition 1 is true
if(condition 2) {
statement 2; //executes when condition 2 is true
}
else{
statement 2; //executes when condition 2 is false
}
} In nested if-statements, the if statement can contain a if or if-else statement inside another if or else-if statement.
Syntax of Nested if-statement is given below.
if(condition 1) {
statement 1; //executes when condition 1 is true
if(condition 2) {
statement 2; //executes when condition 2 is true
}
else{
statement 2; //executes when condition 2 is false
}
}
public class Student {
public static void main(String[] args) {
String address = "Delhi, India";
if(address.endsWith("India")) {
if(address.contains("Meerut")) {
System.out.println("Your city is Meerut");
}else if(address.contains("Noida")) {
System.out.println("Your city is Noida");
}else {
System.out.println(address.split(",")[0]);
}
}else {
System.out.println("You are not living in India");
}
}
}
Output:
Delhi |
What is Switch Statement in Java? | In Java, Switch statements are similar to if-else-if statements. The switch statement contains multiple blocks of code called cases and a single case is executed based on the variable which is being switched. The switch statement is easier to use instead of if-else-if statements. It also enhances the readability of the program.
Points to be noted about switch statement:
-The case variables can be int, short, byte, char, or enumeration. String type is also supported since version 7 of Java
-Cases cannot be duplicate
-Default statement is executed when any of the case doesn't match the value of expression. It is optional.
-Break statement terminates the switch block when the condition is satisfied.
-It is optional, if not used, next case is executed.
-While using switch statements, we must notice that the case expression will be of the same type as the variable. However, it will also be a constant value. |
What is for loop in Java?
| in Java, for loop is similar to C and C++. It enables us to initialize the loop variable, check the condition, and increment/decrement in a single line of code. We use the for loop only when we exactly know the number of times, we want to execute the block of code.
for(initialization, condition, increment/decrement) {
//block of statements
}
public class Calculattion {
public static void main(String[] args) {
// TODO Auto-generated method stub
int sum = 0;
for(int j = 1; j<=10; j++) {
sum = sum + j;
}
System.out.println("The sum of first 10 natural numbers is " + sum);
}
}
Output:
The sum of first 10 natural numbers is 55 |
What is for-each loop in Java? | Java provides an enhanced for loop to traverse the data structures like array or collection. In the for-each loop, we don't need to update the loop variable. The syntax to use the for-each loop in java is given below.
for(data_type var : array_name/collection_name){
//statements
}
Consider the following example to understand the functioning of the for-each loop in Java.
public class Calculation {
public static void main(String[] args) {
// TODO Auto-generated method stub
String[] names = {"Java","C","C++","Python","JavaScript"};
System.out.println("Printing the content of the array names:\n");
for(String name:names) {
System.out.println(name);
}
}
}
Output:
Printing the content of the array names:
Java
C
C++
Python
JavaScript |
What is while loop in Java? | The while loop is also used to iterate over the number of statements multiple times. However, if we don't know the number of iterations in advance, it is recommended to use a while loop. Unlike for loop, the initialization and increment/decrement doesn't take place inside the loop statement in while loop.
It is also known as the entry-controlled loop since the condition is checked at the start of the loop. If the condition is true, then the loop body will be executed; otherwise, the statements after the loop will be executed.
The syntax of the while loop is given below.
The syntax of the while loop is given below.
while(condition){
//looping statements
}
public class Calculation {
public static void main(String[] args) {
// TODO Auto-generated method stub
int i = 0;
System.out.println("Printing the list of first 10 even numbers \n");
while(i<=10) {
System.out.println(i);
i = i + 2;
}
}
}
Output:
Printing the list of first 10 even numbers
0
2
4
6
8
10 |
What is do-while loop in Java?
| The do-while loop checks the condition at the end of the loop after executing the loop statements. When the number of iteration is not known and we have to execute the loop at least once, we can use do-while loop.
It is also known as the exit-controlled loop since the condition is not checked in advance. The syntax of the do-while loop is given below.
do
{
//statements
} while (condition); |
What is Jump Statements? | Consider the following example to understand the functioning of the do-while loop in Java.
Calculation.java
public class Calculation {
public static void main(String[] args) {
// TODO Auto-generated method stub
int i = 0;
System.out.println("Printing the list of first 10 even numbers \n");
do {
System.out.println(i);
i = i + 2;
}while(i<=10);
}
}
Output:
Printing the list of first 10 even numbers
0
2
4
6
8
10 |
What isJava break statement? | As the name suggests, the break statement is used to break the current flow of the program and transfer the control to the next statement outside a loop or switch statement. However, it breaks only the inner loop in the case of the nested loop.
The break statement cannot be used independently in the Java program, i.e., it can only be written inside the loop or switch statement.
The break statement example with for loop
Consider the following example in which we have used the break statement with the for loop.
BreakExample.java
public class BreakExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
for(int i = 0; i<= 10; i++) {
System.out.println(i);
if(i==6) {
break;
}
}
}
}
Output:
0
1
2
3
4
5
6 |
What is Java continue statement? | Unlike break statement, the continue statement doesn't break the loop, whereas, it skips the specific part of the loop and jumps to the next iteration of the loop immediately.
Consider the following example to understand the functioning of the continue statement in Java.
public class ContinueExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
for(int i = 0; i<= 2; i++) {
for (int j = i; j<=5; j++) {
if(j == 4) {
continue;
}
System.out.println(j);
}
}
}
}
Output:
0
1
2
3
5
1
2
3
5
2
3
5 |
What is Java If-else Statement? | The Java if statement is used to test the condition. It checks boolean condition: true or false. There are various types of if statement in Java.
-if statement
-if-else statement
-if-else-if ladder
-nested if statement |
What is Java if Statement? | The Java if statement tests the condition. It executes the if block if condition is true.
Syntax:
if(condition){
//code to be executed
}
Example:
//Java Program to demonstate the use of if statement.
public class IfExample {
public static void main(String[] args) {
//defining an 'age' variable
int age=20;
//checking the age
if(age>18){
System.out.print("Age is greater than 18");
}
}
}
Output:
Age is greater than 18 |
What is Java if-else Statement? | The Java if-else statement also tests the condition. It executes the if block if condition is true otherwise else block is executed.
Syntax:
if(condition){
//code if condition is true
}else{
//code if condition is false
}
Example:
//A Java Program to demonstrate the use of if-else statement.
//It is a program of odd and even number.
public class IfElseExample {
public static void main(String[] args) {
//defining a variable
int number=13;
//Check if the number is divisible by 2 or not
if(number%2==0){
System.out.println("even number");
}else{
System.out.println("odd number");
}
}
}
Output:
odd number |
How to use Ternary Operator in Java? | We can also use ternary operator (? :) to perform the task of if...else statement. It is a shorthand way to check the condition. If the condition is true, the result of ? is returned. But, if the condition is false, the result of : is returned.
Example:
public class IfElseTernaryExample {
public static void main(String[] args) {
int number=13;
//Using ternary operator
String output=(number%2==0)?"even number":"odd number";
System.out.println(output);
}
}
Output:
odd number |
What is Java if-else-if ladder Statement? | The if-else-if ladder statement executes one condition from multiple statements.
Syntax:
if(condition1){
//code to be executed if condition1 is true
}else if(condition2){
//code to be executed if condition2 is true
}
else if(condition3){
//code to be executed if condition3 is true
}
...
else{
//code to be executed if all the conditions are false
}
Example:
//Java Program to demonstrate the use of If else-if ladder.
//It is a program of grading system for fail, D grade, C grade, B grade, A grade and A+.
public class IfElseIfExample {
public static void main(String[] args) {
int marks=65;
if(marks<50){
System.out.println("fail");
}
else if(marks>=50 && marks<60){
System.out.println("D grade");
}
else if(marks>=60 && marks<70){
System.out.println("C grade");
}
else if(marks>=70 && marks<80){
System.out.println("B grade");
}
else if(marks>=80 && marks<90){
System.out.println("A grade");
}else if(marks>=90 && marks<100){
System.out.println("A+ grade");
}else{
System.out.println("Invalid!");
}
}
}
Output:
C grade |
What is Java Nested if statement? | The nested if statement represents the if block within another if block. Here, the inner if block condition executes only when outer if block condition is true.
Syntax:
if(condition){
//code to be executed
if(condition){
//code to be executed
}
}
Example:
//Java Program to demonstrate the use of Nested If Statement.
public class JavaNestedIfExample {
public static void main(String[] args) {
//Creating two variables for age and weight
int age=20;
int weight=80;
//applying condition on age and weight
if(age>=18){
if(weight>50){
System.out.println("You are eligible to donate blood");
}
}
}}
Output:
You are eligible to donate blood |
What is Java Switch Statement? | The Java switch statement executes one statement from multiple conditions. It is like if-else-if ladder statement. The switch statement works with byte, short, int, long, enum types, String and some wrapper types like Byte, Short, Int, and Long. Since Java 7, you can use strings in the switch statement.
In other words, the switch statement tests the equality of a variable against multiple values.
|
Can you provide an example of Switch Example in java? | SwitchExample.java
public class SwitchExample {
public static void main(String[] args) {
//Declaring a variable for switch expression
int number=20;
//Switch expression
switch(number){
//Case statements
case 10: System.out.println("10");
break;
case 20: System.out.println("20");
break;
case 30: System.out.println("30");
break;
//Default case statement
default:System.out.println("Not in 10, 20 or 30");
}
}
}
Output:
20 |
Can you provide an example of Switch Month Example in java? | //Java Program to demonstrate the example of Switch statement
//where we are printing month name for the given number
public class SwitchMonthExample {
public static void main(String[] args) {
//Specifying month number
int month=7;
String monthString="";
//Switch statement
switch(month){
//case statements within the switch block
case 1: monthString="1 - January";
break;
case 2: monthString="2 - February";
break;
case 3: monthString="3 - March";
break;
case 4: monthString="4 - April";
break;
case 5: monthString="5 - May";
break;
case 6: monthString="6 - June";
break;
case 7: monthString="7 - July";
break;
case 8: monthString="8 - August";
break;
case 9: monthString="9 - September";
break;
case 10: monthString="10 - October";
break;
case 11: monthString="11 - November";
break;
case 12: monthString="12 - December";
break;
default:System.out.println("Invalid Month!");
}
//Printing month of the given number
System.out.println(monthString);
}
}
Output:
7 - July |
Can you provide an example of Switch Vowel Example in java? | SwitchVowelExample.java
public class SwitchVowelExample {
public static void main(String[] args) {
char ch='O';
switch(ch)
{
case 'a':
System.out.println("Vowel");
break;
case 'e':
System.out.println("Vowel");
break;
case 'i':
System.out.println("Vowel");
break;
case 'o':
System.out.println("Vowel");
break;
case 'u':
System.out.println("Vowel");
break;
case 'A':
System.out.println("Vowel");
break;
case 'E':
System.out.println("Vowel");
break;
case 'I':
System.out.println("Vowel");
break;
case 'O':
System.out.println("Vowel");
break;
case 'U':
System.out.println("Vowel");
break;
default:
System.out.println("Consonant");
}
}
}
Output:
Vowel |
Is Java Switch Statement is fall-through? | Java Switch Statement is fall-through
The Java switch statement is fall-through. It means it executes all statements after the first match if a break statement is not present. |
Can you provide an example of Java Switch Statement with String? | Example:
SwitchExample2.java
//Java Switch Example where we are omitting the
//break statement
public class SwitchExample2 {
public static void main(String[] args) {
int number=20;
//switch expression with int value
switch(number){
//switch cases without break statements
case 10: System.out.println("10");
case 20: System.out.println("20");
case 30: System.out.println("30");
default:System.out.println("Not in 10, 20 or 30");
}
}
}
Output:
20
30
Not in 10, 20 or 30 |
What is Java Nested Switch Statement? | We can use switch statement inside other switch statement in Java. It is known as nested switch statement.
Example:
NestedSwitchExample.java
//Java Program to demonstrate the use of Java Nested Switch
public class NestedSwitchExample {
public static void main(String args[])
{
//C - CSE, E - ECE, M - Mechanical
char branch = 'C';
int collegeYear = 4;
switch( collegeYear )
{
case 1:
System.out.println("English, Maths, Science");
break;
case 2:
switch( branch )
{
case 'C':
System.out.println("Operating System, Java, Data Structure");
break;
case 'E':
System.out.println("Micro processors, Logic switching theory");
break;
case 'M':
System.out.println("Drawing, Manufacturing Machines");
break;
}
break;
case 3:
switch( branch )
{
case 'C':
System.out.println("Computer Organization, MultiMedia");
break;
case 'E':
System.out.println("Fundamentals of Logic Design, Microelectronics");
break;
case 'M':
System.out.println("Internal Combustion Engines, Mechanical Vibration");
break;
}
break;
case 4:
switch( branch )
{
case 'C':
System.out.println("Data Communication and Networks, MultiMedia");
break;
case 'E':
System.out.println("Embedded System, Image Processing");
break;
case 'M':
System.out.println("Production Technology, Thermal Engineering");
break;
}
break;
}
}
}
Output:
Data Communication and Networks, MultiMedia |