Java First Program

Structure of Java Program

Lets see the basic structure of java program 

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

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

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