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This article mainly explains "case analysis of event monitoring mechanism in Java". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn the case analysis of event monitoring mechanism in Java.

Definition of event monitoring mechanism

Java event monitoring mechanism is widely used in graphical interface programming. We often do a series of operations on the interface, such as typing content in the input box, clicking the login registration button, and so on, some of which are called events. When these operations are carried out, the program will take appropriate measures to respond to these events.

1. Event source object

(1) what can become an event source object?

Only container components and element components can be event source objects.

(2) how to determine who is the event source object on the interface?

When your action occurs on which component, then that component is the event source object.

2. Event monitoring method

(1) event listening method is provided by event source object.

(2) the event listening method captures the actions on the event source object. If an action occurs, the method captures the action, collects the information of the source object and the action information, and then gives the information to the object of the event interface for processing.

3. Event interface (processing class)

After the event interface object gets the information provided by the event listening method, it will call the corresponding event handling method based on this information.

Next, let's feel it through a simple example code:

Train of thought

1. Build a form and install a start button.

2. Define the LoginListener event handling class. This class inherits the ActionListener action event interface and needs to override the abstract methods in the interface.

3. Instantiate the LoginListener event handling object.

4. Add an action listening method to the event handling class object and specify the event handling class object.

Code example:

/ / the first step is to simply construct a form package Login20190318;import java.awt.Color;import java.awt.FlowLayout;import java.awt.Graphics;import javax.swing.JButton;import javax.swing.JFrame;//Draw class inheriting the JFrame class equivalent to the Draw class, that is, the JFrame class directly calls the properties and methods in the JFram class public class Draw extends JFrame {/ / entry main function public void initUI () {this.setSize (1500600) FlowLayout flowlayout=new FlowLayout (FlowLayout.CENTER,5,5); this.setLayout (flowlayout); JButton button=new JButton ("Start"); this.add (button); this.setVisible (true); / / make the form have tablet permissions Graphics graphics=this.getGraphics () / / instantiate the listening method class and pass in the parameter DrawLis drawlis=new DrawLis (graphics); / / make the button button call the listening method button.addActionListener (drawlis) } public static void main (String [] args) {/ / instantiate the Draw class and call the entry function Draw draw=new Draw (); draw.initUI ();}} / / define the class package Login20190318;import java.awt.Color;import java.awt.event.ActionEvent of the event listening method Import java.awt.event.ActionListener;import java.util.Random;import java.awt.Graphics;// implements the listening interface public class DrawLis implements ActionListener {private Graphics g; / / constructor to pass the parameter public DrawLis (Graphics g) {this.g=g } / / define the listening method, draw an ellipse public void actionPerformed (ActionEvent e) {Random random = new Random (); int x=random.nextInt (1600); int y=random.nextInt (1600); g.fillOval (xjinymeng60mai 70) }} at this point, I believe you have a deeper understanding of "case analysis of event monitoring mechanism in Java". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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