Package is defined as the collection of classes, interfaces and sub-packages.it is a name space in which classes are stored
package keyword is used to define the package
package have 2 types
- Built-in package(eg.- java, lang, awt, javax, swing, net, io, util, sql)
- User defined package
Advantage of java Package
- package is used to categorize the classes and interfaces so that they can be easily maintain
- package provide access protection.
- Java package removes naming collision.
\\ save as Pack1.java
public class Pack1
public void msg()
In above example we have to create a package P1. Here package is keyword to define the package.the access of the class is public.
Than msg() method is create to print the our message “Package p1”
After that we compile our code with filename.The following syntax is used to compile the code
javac -d . Pack1.java
The -d switch specifies the destination where to put the generated class file. and .(dot) is used to current directory
after compile the code our class file in generated in package P1
access package from another package
to access the package we have to use import keyword and package name
There are 3 ways to access the package.
- import package.*;
- import package.classname;
- fully qualified name.
Package Access using packagename.*
\\ save as Pack2.java
public static void main(String args)
Pack1 obj = new Pack1();
In above example package MyPack is created. For access the package we have used import keyword and P1.* to access all class in package P1. Than the main method is created of Pack2 and object of class Pack1 is created in main method than method msg() of package P1 is we have access in class Pack2.
Than compile the code as
Javac –d . Pack2.java