MouseListener and MouseMotionListener is an interface in java.awt.event package . Mouse events
are of two types. MouseListener handles the events when the mouse is not in motion. While MouseMotionListener
handles the events when mouse is in motion.
There are five types of events that MouseListener can generate. There are five abstract functions that represent these five events. The abstract functions are :
- void mouseReleased(MouseEvent e) : Mouse key is released
- void mouseClicked(MouseEvent e) : Mouse key is pressed/released
- void mouseExited(MouseEvent e) : Mouse exited the component
- void mouseEntered(MouseEvent e) : Mouse entered the component
- void mousepressed(MouseEvent e) : Mouse key is pressed
There are two types of events that MouseMotionListener can generate. There are two abstract functions that represent these five events. The abstract functions are :
- void mouseDragged(MouseEvent e) : Invoked when a mouse button is pressed in the component and dragged. Events are passed until the user releases the mouse button.
- void mouseMoved(MouseEvent e) : invoked when the mouse cursor is moved from one point to another within the component, without pressing any mouse buttons.
The following programs are a illustration of MouseListener and MouseMotionListener.
1. Program to handle MouseListener events
Java
// Java program to handle MouseListener eventsimport java.awt.*;import java.awt.event.*;import javax.swing.*;class Mouse extends Frame implements MouseListener { // Jlabels to display the actions of events of mouseListener // static JLabel label1, label2, label3; // default constructor Mouse() { } // main class public static void main(String[] args) { // create a frame JFrame f = new JFrame("MouseListener"); // set the size of the frame f.setSize(600, 100); // close the frame when close button is pressed f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // create a new panel JPanel p = new JPanel(); // set the layout of the panel p.setLayout(new FlowLayout()); // initialize the labels label1 = new JLabel("no event "); label2 = new JLabel("no event "); label3 = new JLabel("no event "); // create an object of mouse class Mouse m = new Mouse(); // add mouseListener to the frame f.addMouseListener(m); // add labels to the panel p.add(label1); p.add(label2); p.add(label3); // add panel to the frame f.add(p); f.show(); } // getX() and getY() functions return the // x and y coordinates of the current // mouse position // getClickCount() returns the number of // quick consecutive clicks made by the user // this function is invoked when the mouse is pressed public void mousePressed(MouseEvent e) { // show the point where the user pressed the mouse label1.setText("mouse pressed at point:" + e.getX() + " " + e.getY()); } // this function is invoked when the mouse is released public void mouseReleased(MouseEvent e) { // show the point where the user released the mouse click label1.setText("mouse released at point:" + e.getX() + " " + e.getY()); } // this function is invoked when the mouse exits the component public void mouseExited(MouseEvent e) { // show the point through which the mouse exited the frame label2.setText("mouse exited through point:" + e.getX() + " " + e.getY()); } // this function is invoked when the mouse enters the component public void mouseEntered(MouseEvent e) { // show the point through which the mouse entered the frame label2.setText("mouse entered at point:" + e.getX() + " " + e.getY()); } // this function is invoked when the mouse is pressed or released public void mouseClicked(MouseEvent e) { // getClickCount gives the number of quick, // consecutive clicks made by the user // show the point where the mouse is i.e // the x and y coordinates label3.setText("mouse clicked at point:" + e.getX() + " " + e.getY() + "mouse clicked :" + e.getClickCount()); }} |
Output :
Note : The following program might not run in an online compiler please use an offline IDE
Let’s take another example on MouseListener,the question is:
Q. Write an applet which displays x and y co-ordinate in it’s status bar whenever the user click anywhere in the Applet window.
Ans.
Note: This code is with respect to Netbeans IDE.
Java
//Program of an applet which//displays x and y co-ordinate//in it's status bar,whenever//the user click anywhere in//the applet window.import java.awt.*;import java.awt.event.*;import java.applet.*;public class GFG extends Applet implements MouseListener{public void init(){this.addMouseListener (this);//first "this" represent source//(in this case it is applet which//is current calling object) and//second "this" represent//listener(in this case it is GFG) }public void mouseClicked(MouseEvent m){ int x = m.getX(); int y = m.getY(); String str = "x =" +x+",y = "+y; showStatus(str);} @Override public void mousePressed(MouseEvent e) { } @Override public void mouseReleased(MouseEvent e) { } @Override public void mouseEntered(MouseEvent e) { } @Override public void mouseExited(MouseEvent e) { }} |
Output:
Output showing (x,y) in status bar
Modification: Now our aim is to improve above program so that co-ordinates should display at that point only where click has been made
Note: This code is with respect to Netbeans IDE.
Java
//Co-ordinates should display//at that point only wherever//there is click on canvasimport java.awt.*;import java.awt.event.*;import java.applet.*;public class GFG extends Applet implements MouseListener{private int x,y;private String str = " ";public void init(){this.addMouseListener (this);//first "this" represent source//(in this case it is applet which// is current calling object) and// second "this" represent listener//(in this case it is GFG) }public void paint(Graphics g){g.drawString(str,x,y);}public void mouseClicked(MouseEvent m){ x = m.getX(); y = m.getY(); str = "x =" +x+",y = "+y;repaint(); // we have made this//call because repaint() will//call paint() method for us.//If we comment out this line,//then we will see output//only when focus is on the applet//i.e on maximising the applet window//because paint() method is called//when applet screen gets the focus.//repaint() is a method of Component//class and prototype for this method is://public void repaint()} public void mouseEntered(MouseEvent m)//over-riding all the methods given by// MouseListener{} public void mouseExited(MouseEvent m){} public void mousePressed(MouseEvent m){} public void mouseReleased(MouseEvent m){}} |
Output
Output showing (x,y) in canvas
Now one more unusual thing will come in output which is that, we will not able to see previous co-ordinates.But why?
In Java, before calling paint() method, it calls one more method which is update() and it do the following things:
- it repaints the applet background with current color.
- it then calls paint().
Now to see previous co-ordinates as well:
we have to over-ride update() method also and it’s prototype is similar to paint().
Further Modification To see previous co-ordinates as well:
Note: This code is with respect to Netbeans IDE.
Java
//Co-ordinates should display//at that point only wherever//there is click on canvas and also//able to see the previous coordinatesimport java.awt.*;import java.awt.event.*;import java.applet.*;public class GFG extends Applet implements MouseListener{private int x,y;private String str = " ";public void init(){this.addMouseListener (this);}public void paint(Graphics g){g.drawString(str,x,y);}public void update(Graphics g){paint(g);}public void mouseClicked(MouseEvent m){ x = m.getX(); y = m.getY(); str = "x =" +x+",y = "+y;repaint();} public void mouseEntered(MouseEvent m){} public void mouseExited(MouseEvent m){} public void mousePressed(MouseEvent m){} public void mouseReleased(MouseEvent m) { }} |
Output
Output showing previous co-ordinate as well
2. Program to handle MouseMotionListener events
Java
// Java Program to illustrate MouseMotionListener eventsimport java.awt.*;import java.awt.event.*;import javax.swing.*;class Mouse extends Frame implements MouseMotionListener { // Jlabels to display the actions of events of MouseMotionListener static JLabel label1, label2; // default constructor Mouse() { } // main class public static void main(String[] args) { // create a frame JFrame f = new JFrame("MouseMotionListener"); // set the size of the frame f.setSize(600, 400); // close the frame when close button is pressed f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // create new panel JPanel p = new JPanel(); // set the layout of the panel p.setLayout(new FlowLayout()); // initialize the labels label1 = new JLabel("no event "); label2 = new JLabel("no event "); // create an object of mouse class Mouse m = new Mouse(); // add mouseListener to the frame f.addMouseMotionListener(m); // add labels to the panel p.add(label1); p.add(label2); // add panel to the frame f.add(p); f.show(); } // getX() and getY() functions return the // x and y coordinates of the current // mouse position // invoked when mouse button is pressed // and dragged from one point to another // in a component public void mouseDragged(MouseEvent e) { // update the label to show the point // through which point mouse is dragged label1.setText("mouse is dragged through point " + e.getX() + " " + e.getY()); } // invoked when the cursor is moved from // one point to another within the component public void mouseMoved(MouseEvent e) { // update the label to show the point to which the cursor moved label2.setText("mouse is moved to point " + e.getX() + " " + e.getY()); }} |
Output :
3. Java program to illustrate MouseListener and MouseMotionListener events
simultaneously
Java
// Java program to illustrate MouseListener// and MouseMotionListener events// simultaneouslyimport java.awt.*;import java.awt.event.*;import javax.swing.*;class Mouse extends Frame implements MouseMotionListener, MouseListener { // Jlabels to display the actions of events of MouseMotionListener and MouseListener static JLabel label1, label2, label3, label4, label5; // default constructor Mouse() { } // main class public static void main(String[] args) { // create a frame JFrame f = new JFrame("MouseListener and MouseMotionListener"); // set the size of the frame f.setSize(900, 300); // close the frame when close button is pressed f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // create new panel JPanel p = new JPanel(); JPanel p1 = new JPanel(); // set the layout of the frame f.setLayout(new FlowLayout()); JLabel l1, l2; l1 = new JLabel("MouseMotionListener events :"); l2 = new JLabel("MouseLIstener events :"); // initialize the labels label1 = new JLabel("no event "); label2 = new JLabel("no event "); label3 = new JLabel("no event "); label4 = new JLabel("no event "); label5 = new JLabel("no event "); // create an object of mouse class Mouse m = new Mouse(); // add mouseListener and MouseMotionListenerto the frame f.addMouseMotionListener(m); f.addMouseListener(m); // add labels to the panel p.add(l1); p.add(label1); p.add(label2); p1.add(l2); p1.add(label3); p1.add(label4); p1.add(label5); // add panel to the frame f.add(p); f.add(p1); f.show(); } // getX() and getY() functions return the // x and y coordinates of the current // mouse position // getClickCount() returns the number of // quick consecutive clicks made by the user // MouseMotionListener events // invoked when mouse button is pressed // and dragged from one point to another // in a component public void mouseDragged(MouseEvent e) { // update the label to show the point // through which point mouse is dragged label1.setText("mouse is dragged through point " + e.getX() + " " + e.getY()); } // invoked when the cursor is moved from // one point to another within the component public void mouseMoved(MouseEvent e) { // update the label to show the point to which the cursor moved label2.setText("mouse is moved to point " + e.getX() + " " + e.getY()); } // MouseListener events // this function is invoked when the mouse is pressed public void mousePressed(MouseEvent e) { // show the point where the user pressed the mouse label3.setText("mouse pressed at point:" + e.getX() + " " + e.getY()); } // this function is invoked when the mouse is released public void mouseReleased(MouseEvent e) { // show the point where the user released the mouse click label3.setText("mouse released at point:" + e.getX() + " " + e.getY()); } // this function is invoked when the mouse exits the component public void mouseExited(MouseEvent e) { // show the point through which the mouse exited the frame label4.setText("mouse exited through point:" + e.getX() + " " + e.getY()); } // this function is invoked when the mouse enters the component public void mouseEntered(MouseEvent e) { // show the point through which the mouse entered the frame label4.setText("mouse entered at point:" + e.getX() + " " + e.getY()); } // this function is invoked when the mouse is pressed or released public void mouseClicked(MouseEvent e) { // getClickCount gives the number of quick, // consecutive clicks made by the user // show the point where the mouse is i.e // the x and y coordinates label5.setText("mouse clicked at point:" + e.getX() + " " + e.getY() + "mouse clicked :" + e.getClickCount()); }} |
output :
MouseListener vs MouseMotionListener
- MouseListener: MouseListener events are invoked when the mouse is not in motion and is stable . It generates events such as mousePressed, mouseReleased, mouseClicked, mouseExited and mouseEntered (i.e when the mouse buttons are pressed or the mouse enters or exits the component). The object of this class must be registered with the component and they are registered using addMouseListener() method.
- MouseMotionListener: MouseMotionListener events are invoked when the mouse is in motion . It generates events such as mouseMoved and mouseDragged (i.e when the mouse is moved from one point to another within the component or the mouse button is pressed and dragged from one point to another ). The object of this class must be registered with the component and they are registered using addMouseMotionListener() method.
