Java package

PACKAGES

• Packages is a collection of different types of java files.
• Packages is a group of class and interfaces.
• They're in built.
• It is similar to a ''folder''.
• To use a class or a package from the library, you need to use the ''import'' keyword.

THERE ARE TWO TYPES OF PACKAGES:

Type of package

• In build packages
• User defined packages.

System defined packages:

They are in-built in the system.

• java.lang = language package
• java.util = utility package
• java.io = input/output package
• java.awt = GUI package
• java.net = networking package
• java.applet = applet package
• java.sql= database package

User defined packages:

To create your own package.

 Ways to create user-defined packages:

1. creating a package
2. Importing a package.

CREATE PACKAGE:

• package package_name;

EX: package    college;

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Keyword      Package name

• Declare class as public 

EX: public class classname.

• Save & compile the file

IMPORTING PACKAGES:

Import packagename.*;

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Keyword

EX: import college.*;

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This statement with import all the classes and interfaces in college package.

EXAMPLE:

//package program

package college;

public class course  

{

string dept;

string year;

course(String d, String y)

{

}

//importing the package

import college.*;

class packdemo

{

public static void main(String as[])

{

course C=new course(''C.s'',''2nd year'');

C.display();

dept=d;

year=y;

}

public void display()

{

system.out.println(''Dept:''+dept);

system.out.println(''Year:''+year);

}

}

}

OUTPUT:

Dept: C.s

Year: 2nd year