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Package in Java

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Package in Java

A package is a namespace that organizes a set of related classes and interfaces.

Package is a collection of classes, interfaces, multiple sub packages etc.

Some of the existing packages in Java are:

·        java.lang - bundles the fundamental classes

·        java.io - classes for input , output functions are bundled in this package

Advantages of packages -:

·        Reusability:  Reusability of code is one of the most important requirements in the software industry. Reusability saves time, effort and also ensures consistency. A class once developed can be reused by any number of programs wishing to incorporate the class in that particular program.

·        Easy to locate the files.

·        In real life situation there may arise scenarios where we need to define files of the same name. This may lead to “name-space collisions”. Packages are a way of avoiding “name-space collisions”.

Types of package:

1.      User defined package: The package we create is called user-defined package.

2.      Built-in package: The already defined package like java.io.*, java.lang.* etc are known as built-in packages

// define package

package packagename;

// import packages

Import mypack;

//class declaration

class Sample


// instance members

//method implementation







Define a package

package  <package name>;

Example of package of creation

package mypack;

class Book


 String bookname;

 String author;

 Book(String b, String c)


  this.bookname = b;

  this.author = c;


 public void show()


  System.out.println(bookname+" "+ author);




class test


 public static void main(String[] args)


  Book bk = new Book("java","Herbert");





Access of package-:


import java.util.Date;

Subpackage in java-:

Package inside the package is called the subpackage. It should be created to categorize the package further.

Example of sub packages

package com.midstick.core; 

class Sample{ 

  public static void main(String args[]){ 

   System.out.println("Demo subpackage"); 



package com.mindstick.core

import static java.lang.Math.*;

public class Test


    public static void main(String[] args)





output -: 12





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