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This article mainly introduces "what is the execution order of Java listeners ActionListener and MouseListener". In daily operation, I believe many people have doubts about the execution order of Java listeners ActionListener and MouseListener. Xiaobian consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts of "what is the execution order of Java listeners ActionListener and MouseListener?" Next, please follow the editor to study!

Basic concept

Listener (Listener): the listener is used to listen to the creation, destruction, addition, modification, deletion and other actions of some objects and information in web applications, and then make corresponding response processing. When the state of the scope object changes, the server automatically calls the method in the listener object. It is often used to count the number of online people and online users, to initialize information when the system is loaded, to count the number of visits to the website, and so on.

The listener interface that ActionListener:ActionListener uses to receive action events. Classes interested in handling action events can implement this interface, and objects created with this class can be registered with the component using the component's addActionListener method. When an action event occurs, the actionPerformed method of the object is called.

MouseListener: classes that handle mouse events either implement this interface (and all the methods it contains) or extend the abstract class MouseAdapter (overriding only the required methods). The listener object created from this class is then registered with the component using the component's addMouseListener method. Mouse events are generated when the mouse is pressed, released, or clicked (pressed and released). Mouse events are also generated when the mouse cursor enters or leaves the component. When a mouse event occurs, the appropriate method in the listener object is called and the MouseEvent is passed to the method.

MouseAdapter: an abstract adapter class for receiving mouse events. The methods in this class are empty. This class exists as a convenience for creating listener objects.

Development environment

JAVA 1.8

Eclipse 201803

Source code import java.awt.*;import java.awt.event.*;import javax.swing.*;public class GUIDEMO {public static void main (String [] args) {/ / TODO automatically generated method stub EventQueue.invokeLater (()-> {JFrame frame = new MyFrame (); frame.setTitle ("DrawTest") Frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE); frame.setVisible (true);}); System.out.println ("Hello World");} public void print (Object obj) {System.out.println (obj);}} class MyFrame extends JFrame {private static final int DEFAULT_WIDTH = 400 Private static final int DEFAULT_HEIGHT = 400; public MyFrame () {setSize (DEFAULT_WIDTH,DEFAULT_HEIGHT); setLocation (100200); setLayout (new FlowLayout ()); JButton but=new JButton ("DEMOButton"); but.addActionListener (event- > {print ("action")) }); but.addMouseListener (new MouseAdapter () {public void mouseEntered (MouseEvent e) {print ("enter") } public void mouseExited (MouseEvent e) {print ("exit");} public void mouseClicked (MouseEvent e) {print ("click") }); add (but);} public void print (Object obj) {System.out.println (obj);} public Dimension getPreferredSize () {return new Dimension (DEFAULT_WIDTH, DEFAULT_HEIGHT);}} run the result

Make a brief summary

ActionListener executes before MouseListener

Note: in a teaching video, ActionListener is performed after MouseListener in the environment of JAVA 1.6.

Differences and connections between mouse listeners and action listeners

1. English names: MouseListener and ActionListener

Both are interfaces and inherit the same parent class EventListenr

When you use it, you need to define the class implementation interface.

two。 Action

MouseListener: can be used for mouse click, press, release, enter, leave, can be used for interfaces, component classes

ActionListener: used on top of components (not JPanel, JFrame or JLabel)

JButton can, and so can JTextField.

3. Difference

MouseListener is more versatile in function and more selective in adding objects.

ActionListener is relatively simple in function and can only be applied to a few simple components, all of which are click events.

ActiMouseListener has an e.getActionCommand () method, but ActionListener does not, so it cannot be determined

Which button is pressed or released, so if there are too many buttons, you can't use MouseListener.

/ / MouseListener section: public void mousePressed (MouseEvent e) {/ / TODO Auto-generated method stub g.setColor (Color.blue); draw (100maiden 400, 400, 400, 400); draw (400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400 and 400); draw (400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400 and 400). } / / the same function ActionListener section: if (e.getActionCommand (). Equals ("Shevinski Triangle") {g.setColor (Color.blue); draw (100meme 400, 400, 400, 400, 400, 400); draw (400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400, 400 and 400). Draw (700, 400, 400, 400, 400, 400, 10); draw (400, 400, 700, 400, 400, 400, 400, 400, 400, 400, 400, and 400);}

At this point, the study on "what is the execution order of Java listeners ActionListener and MouseListener" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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