Java Tutorial : Java package access

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Java Tutorial : Java package access

Java Tutorial : Java package access

1.import packagename.*;

A.java

package mypack;

public class A
{

    public void message()
    {
        System.out.println("Class A messgage has been called.....");

    }

}

B.java

package util;

/**
 * If you use packagename.* then all the classes and interfaces of this package
 * will be accessible but not sub packages.
 *
 * The import keyword is used to make the classes and interface of
 * another package accessible to the current package.
 */
import mypack.*;

public class B
{

    public static void main(String[] args)
    {
        A a = new A();
        a.message();
    }

}

Output

Class A messgage has been called.....

2.import packagename.classname;

A.java

package mypack;

public class A
{

    public void message()
    {
        System.out.println("Class A messgage has been called.....");

    }

}

B.java

package util;

/**
 * If you import packagename.classname then only declared class of 
 * this package will be accessible.
 */
import mypack.A;

public class B
{

    public static void main(String[] args)
    {
        A a = new A();
        a.message();
    }

}

Output

Class A messgage has been called....

3.Fully qualified name.

A.java

package mypack;

public class A
{

    public void message()
    {
        System.out.println("mypack Class A messgage method has been called.....");

    }

}

A.java

package util;

public class A
{

    public static void main(String[] args)
    {
        /*
         * If you use fully qualified name then only declared class of this
         * package will be accessible. Now there is no need to import. But you
         * need to use fully qualified name every time when you are accessing
         * the class or interface.
         * 
         * It is generally used when two packages have same class name e.g.
         * java.util and java.sql packages contain Date class.
         */
        mypack.A a = new mypack.A();
        a.message();
    }

}

Output

mypack Class A messgage method has been called.....

To Download PackageAccessApp Project Click the below link
https://sites.google.com/site/javaee4321/java/PackageAccessApp.zip?attredirects=0&d=1

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