Hello Java Program

Hello java program is first program in java. Its very easy coding , you can get idea about how to type program and save with java extension. then compile and execute it.

Step 1: 

Download: Text editor like Note pad or Notepad ++ (N++ recomended)

Step 2: 

Type your program in text editor then save with classname.java extension under one foldre, its called directries.

Step 3: 

Goto cmd then point your folder( eg: cd.. and cd..finaly get c drive then cd folder name. then type

for compile : javac ProgramName.java

for execute : java ProgramName

Java programming source code

class HelloWorld
{
   public static void main(String args[])
   {
      System.out.println("Hello World");
   }
}

"Hello World" is passed as an argument to println method, you can print whatever you want. There is also a print method which doesn't takes the cursor to beginning of next line as println does. System is a class, out is object of PrintStream class and println is the method.
Output of program:  Hello World


Note :

When we consider a Java program, it can be defined as a collection of objects that communicate via invoking each other's methods. Let us now briefly look into what do class, object, methods, and instance variables mean.

·        Object − Objects have states and behaviors. Example: A dog has states - color, name, breed as well as behavior such as wagging their tail, barking, eating. An object is an instance of a class.
·        Class − A class can be defined as a template/blueprint that describes the behavior/state that the object of its type supports.
·        Methods − A method is basically a behavior. A class can contain many methods. It is in methods where the logics are written, data is manipulated and all the actions are executed.
·        Instance Variables − Each object has its unique set of instance variables. An object's state is created by the values assigned to these instance variables.
First Java Program
Let us look at a simple code that will print the words Hello World.

Example:
public class MyFirstJavaProgram {

   /* This is my first java program.
    * This will print 'Hello World' as the output
    */

   public static void main(String []args) {
      System.out.println("Hello World"); // prints Hello World
   }
}

Let's look at how to save the file, compile, and run the program. Please follow the subsequent steps
·   Open notepad and add the code as above.
·   Save the file as: MyFirstJavaProgram.java.
·    Open a command prompt window and go to the directory where you saved the class. Assume it's C:\.
·     Type 'javac MyFirstJavaProgram.java' and press enter to compile your code. If there are no errors in your code, the command prompt will take you to the next line (Assumption : The path variable is set).
·     Now, type ' java MyFirstJavaProgram ' to run your program.
·     You will be able to see ' Hello World ' printed on the window.
Output:

C:\> javac MyFirstJavaProgram.java
C:\> java MyFirstJavaProgram
Hello World

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