Explanation of Java event handling steps
- 2021-06-28 12:46:04
- OfStack
What is an event?
A user's action on a component is called an event.
Event source: An GUI component object capable of generating events. Event Processing: A method that accepts, parses, and processes event class objects to achieve user interaction. Event listener: A class that can handle events.Processing event steps:
Assume the event is XXXX
1. Register an event listener object for an event to the event source
addXXXXListener(...);
2. Event listeners designed to handle such events
class Class name implements XXXXListener{
Rewrite XXXXListener Methods in interfaces
}
Explain:
To design a listener that can handle XXXX events, you only need to write a class that implements the XXXXListener interface, because the XXXXListener interface already defines a method for handling XXXX events.
eg:
import java.awt.*;
import java.awt.event.*;
class A implements ActionListener{
public void actionPerformed(ActionEvent e){// Click Event
System.out.println("haha");
}
}
public class text{
public static void main(String[] args){
Frame f=new Frame();
Button bn=new Button("ok");
f.add(bn);
A aa =new A();
bn.addActionListener(aa);
f.pack();// Show content height and width only
f.setVisible(true);
}
}
What are the events:
ActionEvent: Events that occur when a component is activated KeyEvent: Events occurring while operating the keyboard MouseEvent: Occurs when the mouse is operated WindowsEvent: Events that occur when a window is manipulatedsummary