General Format of Java Program

General Format of Java Program

 package statement
 import statement
 global declaration
 class ClassName
 {
    public static void main(String args[])
    {
        Statements
    ----------
    }
 }

Package statement

• The package statement defines a namespace in which classes are stored.
• If you omit the package statement, the class names are put into the default package, which has no name.
• For ex: package ccit;

Import statement

• Java provides us many library classes which are defined in different packages
• If we want to use these classes then we have to import them.
• For eg:
• import java.awt.Button;
• import java.awt.TextField;
• import java.awt.*;

Global Declaration

• In this section we can define only user defined data types such as classes, interfaces or enums etc.
• In this section we cannot define variables or functions.

Function main

• This is entry point of our standard java program.
• Execution of java program begins with function main.
• Function main must be in a class.
• public: it indicates that main function is assessable
• static: it indicates that function main can be called without creating object.
• void: it indicates that function main doesn't return any value.
• String args[]: it is used to receive command line arguments.

Output Statements

• Java provide System.out object. This object is attached to our standard output device.
• This object is used to send data to standard output device.
• It provides us methods print(), println(), printf()..etc to write data into the object .

print method

  class demo
  {
    public static void main(String args[])
    {
        System.out.println("Welcome to Java");
    }
  }

  Welcome to Java
  

println method

  class demo
  {
    public static void main(String args[])
    {
        System.out.println("Welcome to Java");
        System.out.println("CCIT");
        System.out.println("Amravati");
    }
  }

Welcome to Java
CCIT
Amravati
  

printf method

  class demo
  {
    public static void main(String args[])
    {
        int a=3,b=2,c;
        c=a+b;
        System.out.printf("Sum is %d",c);
    }
  }

Sum is 5