SIMPLE PROGRAM OF JAVA

To create a simple java program, We need to create a class that contains main method.
Let's understand the requirement first.

REQUIREMENT FOR SIMPLE PROGRAM 

For executing any java program, you need to

• Install the JDK if you don't have installed it, download the JDK and install it.
• Set path of the jdk/bin directory. how-to-set-path-in-java
• Create the java program
• Compile and run the java program.

LETS BEGIN TO WRITE THE JAVA PROGRAM

STEP 1

To write the simple program, open notepad by start menu -> All Programs -> Accessories -> notepad Then write the simple program.

save this file as Simple.java

To compile:	javac Simple.java
To execute:	java Simple

STEP 2 

As displayed in the above diagram, write the simple program of java in notepad and saved it as Simple.java. To compile and run this program, you need to open 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:\rohit(it is my folder name you write according to yours). Write here:

To compile:	javac Simple.java
To execute:	java Simple

TIME TO UNDERSTAND THE PROGRAM......

Let's understand  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 which represents visibility, it means it is visible to all.
• static is a keyword, if we declare any method as static, it is known as static method. The core advantage of static method is that there is no need to create object to invoke the static method. The main method is executed by the JVM, so it doesn't require to create 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 startup of the program.
• String[] args is used for command line argument. We will learn it later.
• System.out.println() is used print statement. We will learn about the internal working of System.out.println statement later.

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