Adapter class in Java

By using the adapter classes, we can implement Listener interfaces. With the help of adapter classes, we can save code as it provides all implementation methods of listener interfaces

Advantages of Adapter classes

• Adapter class offers a means of incorporating similar patterns into the class.
• It offers a pluggable development kit for applications.
• By using the adapter class, it makes the class more versatile.
• Adapter classes makes  easier for unrelated classes to collaborate.
• It offers diverse approaches to using classes.
• It makes lessons more transparent.

To use the adapter class,mustd to import the following packages

• java.awt.event
• java.awt.dnd
• javax.swing.event

java.awt.event adapter class

java.awt.dnd adapter class

java.swing.event adapter class

Program for Java Mouse Adapter

MouseAdapter1.java

import java.awt.*;  
import java.awt.event.*;  
public class MouseAdapter1 extends MouseAdapter{  
    Frame f1;  // Creating a frame
    // Default constructor
    MouseAdapter1(){  
        f1=new Frame("Mouse Adapter");  // Setting the name of the frame as MouseAdapter
        f1.addMouseListener(this); 
        f1.setSize(400,400);  // Setting the size of frame 
        f1.setLayout(null);  
        f1.setVisible(true);  // Giving visibility to the frame
     // This inner class is used to close the window
        f1.addWindowListener (new WindowAdapter() 
{    
            public void windowClosing (WindowEvent e1) {    
                f1.dispose();    
            }    
        });   
    }  
    public void mouseClicked(MouseEvent e) {  
        Graphics g1=f1.getGraphics();  
        g1.setColor(Color.BLACK);  
        g1.fillOval (e.getX(), e.getY(), 20, 15);    
    }   
public static void main(String[] args) {  
    new MouseAdapter1();  
}  
}

Output

Java Window Adapter Program

This program is used to create windows using awt packages

Adapter.java

// Necessary  packages are imported
import java.awt.*;    
import java.awt.event.*;    
public class Adapter {  
// Creating a Frame  f1  
    Frame f1;    
// default class constructor  
    Adapter() {    
// creating a frame with the title  
        f1 = new Frame ("Adapter Windows");    
// overriding the window closing() method   
        f1.addWindowListener (new WindowAdapter() {    
            public void windowClosing (WindowEvent e1) {    
                f1.dispose();    
            }    
        });    
         // setting the size of the frame
        f1.setSize (350, 450);    
        // setting the size of the frame
        f1.setLayout (null);    
        f1.setVisible (true);    
    }    
// main method  
public static void main(String[] args) {    
    new Adapter();    
// Default constructor 
// Name of the constructor should be same as class name
}    // main method for the program
}  //Adapter

Output

Java MouseMotionAdapter Program

MouseMotionAdapter1.java

import java.awt.*;    
import java.awt.event.*;     
public class MouseMotionAdapter1 extends MouseMotionAdapter {     
// Creating a frame f1    
Frame f1;    
    MouseMotionAdapter1() {    
        f1 = new Frame ("Adapter Program for mouse motion");    
        f1.addMouseMotionListener (this);    
// Setting the size to 300 X 300 for the frame
        f1.setSize (300, 300);    
        f1.setLayout (null);    
        f1.setVisible (true);       
        f1.addWindowListener (new WindowAdapter() {    
            public void windowClosing (WindowEvent e1) {    
                f1.dispose();    
            }    
        });    
    }    
public void mouseDragged (MouseEvent e1) {    
// Creating object for Graphics class to draw in the frame
Graphics g1 = f1.getGraphics();    
// Setting the color to red
    g1.setColor (Color.RED);    
// Drawing oval shaped to draw the described message
g1.fillOval (e1.getX(), e1.getY(), 10, 10);    
}    
// Main method for the program
public static void main(String[] args) {    
    new MouseMotionAdapter1();    
// Default constructor
//Constructor name  should be same as class name i.e., MouseMotionAdapter1 
}    
}

Output

Java KeyAdapter Program

KeyAdapter1.java

//Importing the required packages
import java.awt.*;    
import java.awt.event.*;    
public class KeyAdapter1 extends KeyAdapter {    
// Creating label and textarea  component variables
    Label l1;    
    TextArea area1;    
    Frame f1;    
// class constructor  
    KeyAdapter1() {    
// creating the Frame with the title  
        f1 = new Frame ("Adapter for Key ");    
// creating the Label  
        l1 = new Label();    
// setting the location of the label   
        l1.setBounds (20, 50, 200, 20);    
// creating the text area  
        area1 = new TextArea();  
        area1.setBounds (20, 80, 300, 300);    
        area1.addKeyListener(this);    
// Adding the label and text area to the frame by using the add  method
        f1.add(l1);  
       f1.add(area1);    
// setting the size  
        f1.setSize (400, 400);  
//layout of the frame  
        f1.setLayout (null);
//visibility of the frame    
        f1.setVisible (true);
        f1.addWindowListener (new WindowAdapter() {    
            public void windowClosing (WindowEvent e) {    
                f1.dispose();    
            }    
        });    
    }    
    public void keyReleased (KeyEvent e) {    
        String text1 = area1.getText();    
// splitting the given String
        String words1[] = text1.split ("\\s");    
        l1.setText ("Words: " + words1.length + " Characters:" + text1.length());    
    }    
  // main method for the program 
    public static void main(String[] args) {    
        new KeyAdapter1();    
    }    
}

Output