Package in Java | Example

→ Package in java encapsulate a group of classes, interface and sub package.

Note:- Meaning of Subpackage:- Packages that are inside another package are the subpackages.

Types of packages in Java:-

built-in package :- There are Many in built in package such as java, lang, awt, javax, swing, net, io, util, sql etc.
user-defined package:- user-defined package which is created by the Programmer(User) is Known as User defined package..
Syntax: of user-defined package

package <package name>;

Advantage of Java Package

Easy to manage because class are categories.
Package provides access protection using access modifier.
removes naming collision.
Represent Scope.
Package helps in reusability of code.

1) Example

 
package mypack1; 
public class A{  
 public static void main(String args[]){  
    System.out.println("Welcome to Package");  
   }  
}  

Output

How to Compile and run java package Example

Compile: javac -d . A.java

Run: java mypack1.A

. dot for current directory

-d Destination(where put class file)

Note:- (Javac One Space -d again One space dot one space classname.java)

How to access package from another package?

There are following way.

2) without import(fully qualified name)

A) Example : import the packagename.*

 // save file  A.java
 package mypack1;   
public class A{    
 public void msg(){
    System.out.println("Welcome to Package");    
  }    
}    

// save file  Test.java
package mypack2;    
import mypack1.*;  // calling pack1 package or you can call class name  
    
 class Test{    
  public static void main(String args[]){    
   A a = new A();    
  a.msg();    
  }    
}    
 

Output

Compile:- javac -d . A.java

Compile: javac -d . Test.java

Run : java mypack2.Test

B) Example : import package.classname

 package mypack1;   
 public class A{    
 public void msg(){
    System.out.println("Welcome to Package in Java");    
  }    
}    

package mypack2;    
import mypack1.A;  // calling pack1 package or you can call class name  
    
 class Test{    
  public static void main(String args[]){    
   A a = new A();    
  a.msg();    
  }    
}    

Output:-

2) Example Without import

 package mypack1;   
 public class A{    
 public void msg(){
    System.out.println("Example Without import Package");    
  } }    

package mypack2;       
 class Test{    
  public static void main(String args[]){    
  mypack1.A a = new mypack1.A(); 
   a.msg();       
  } }    

Output:-

Without import Package class in Java Example

Sub Package

→ Package inside the Package is Called Sub package.

  
package elibraryportal.com;
   class SubpackageEx {
 public static void main (String args []){
 System.out.println("Hello Sub Package Example in Java");
  } }  

Output:-

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OOPs Concepts

Package in Java | Example

Types of packages in Java:-

Advantage of Java Package

1) Example

How to Compile and run java package Example

How to access package from another package?

A) Example : import the packagename.*

B) Example : import package.classname

2) Example Without import

Sub Package