Java First Program

Structure of Java Program

Lets see the basic structure of java program

class className {

    public static void main(String args[]) {
    }
}

class className {

public static void main(String args[]) {

}

Here:

class- is write to create a class.

class_name – is a name of class. It is a identifier.

public– is a access modifier is used for main() method accessible for every one.

static- class contain a main() method not have a object and if we want a access a class without create a object of that class then method main() must be declare as a static.

void- is a return type. Void denotes that main() method return noting.

main()– main is a method from where execution of program starts.

Syntax to print statement

System.out.println();

1	System.out.println();

Here:

System: System is a predefined class, it is a final class in java.lang package

out: is a static member of the System class, and is an instance ofjava.io.PrintStream

println() or print(): is a method of java.io.PrintStream. Any thing written inside the round bracket will be print.

Simple java program to print Hello Students

class HelloStudents {

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

class HelloStudents {

public static void main(String args[]) {

System.out.println("Hello Students");

}

Save and Run Program

Save this program with HelloStudents.java name.

Goto start menu and type ”cmd” and press enter to open command prompt.

Use the cd command ( cd dir_name or .. to go up one directory) to navigate to the directory where HelloStudents.java program is save.

For example: HelloStudents.java saved in a “x” folder of c directory.

Then type cd c:\ [press enter]

c:>cd c:\ x [press enter]

c\x:>_

for compile write (with file name) : javac HelloStudents.java // here javac is a colpiler

for run write (with class name): java HelloStudents

Output

Hello Students

1	Hello Students