awt

Posted 2020-06-14

摘自：http://www.ntu.edu.sg/home/ehchua/programming/java/J4a_GUI.html

1.ActionListener

import java.awt.*;        // Using AWT container and component classes
import java.awt.event.*;  // Using AWT event classes and listener interfaces
 
// An AWT program inherits from the top-level container java.awt.Frame
public class AWTCounter extends Frame implements ActionListener {
   private Label lblCount;    // Declare component Label
   private TextField tfCount; // Declare component TextField
   private Button btnCount;   // Declare component Button
   private int count = 0;     // Counter‘s value
 
   /** Constructor to setup GUI components and event handling */
   public AWTCounter () {
      setLayout(new FlowLayout());
         // "super" Frame sets its layout to FlowLayout, which arranges the components
         //  from left-to-right, and flow to next row from top-to-bottom.
 
      lblCount = new Label("Counter");  // construct Label
      add(lblCount);                    // "super" Frame adds Label
 
      tfCount = new TextField("0", 10); // construct TextField
      tfCount.setEditable(false);       // set to read-only
      add(tfCount);                     // "super" Frame adds tfCount
 
      btnCount = new Button("Count");   // construct Button
      add(btnCount);                    // "super" Frame adds Button
 
      btnCount.addActionListener(this);
         // Clicking Button source fires ActionEvent
         // btnCount registers this instance as ActionEvent listener
 
      setTitle("AWT Counter");  // "super" Frame sets title
      setSize(250, 100);        // "super" Frame sets initial window size
 
      // System.out.println(this);
      // System.out.println(lblCount);
      // System.out.println(tfCount);
      // System.out.println(btnCount);
 
      setVisible(true);         // "super" Frame shows
 
      // System.out.println(this);
      // System.out.println(lblCount);
      // System.out.println(tfCount);
      // System.out.println(btnCount);
   }
 
   /** The entry main() method */
   public static void main(String[] args) {
      // Invoke the constructor to setup the GUI, by allocating an instance
      AWTCounter app = new AWTCounter();
   }
 
   /** ActionEvent handler - Called back upon button-click. */
   @Override
   public void actionPerformed(ActionEvent evt) {
      ++count; // increase the counter value
      // Display the counter value on the TextField tfCount
      tfCount.setText(count + ""); // convert int to String
   }
}

2.WindowEvent

import java.awt.*;        // Using AWT containers and components
import java.awt.event.*;  // Using AWT events and listener interfaces
 
// An AWT GUI program inherits the top-level container java.awt.Frame
public class WindowEventDemo extends Frame
      implements ActionListener, WindowListener {
      // This class acts as listener for ActionEvent and WindowEvent
      // Java supports only single inheritance, where a class can extend
      // one superclass, but can implement multiple interfaces.
 
   private TextField tfCount;
   private Button btnCount;
   private int count = 0;  // Counter‘s value
 
   /** Constructor to setup the UI components and event handling */
   public WindowEventDemo() {
      setLayout(new FlowLayout()); // "super" Frame sets to FlowLayout
 
      add(new Label("Counter"));   // "super" Frame adds an anonymous Label
 
      tfCount = new TextField("0", 10); // Allocate TextField
      tfCount.setEditable(false);       // read-only
      add(tfCount);                     // "super" Frame adds tfCount
 
      btnCount = new Button("Count");  // Declare and allocate a Button
      add(btnCount);                   // "super" Frame adds btnCount
 
      btnCount.addActionListener(this);
        // btnCount fires ActionEvent to its registered ActionEvent listener
        // btnCount adds "this" object as an ActionEvent listener
 
      addWindowListener(this);
        // "super" Frame fires WindowEvent to its registered WindowEvent listener
        // "super" Frame adds "this" object as a WindowEvent listener
 
      setTitle("WindowEvent Demo"); // "super" Frame sets title
      setSize(250, 100);            // "super" Frame sets initial size
      setVisible(true);             // "super" Frame shows
   }
 
   /** The entry main() method */
   public static void main(String[] args) {
      new WindowEventDemo();  // Let the construct do the job
   }
 
   /** ActionEvent handler */
   @Override
   public void actionPerformed(ActionEvent evt) {
      ++count;
      tfCount.setText(count + "");
   }
 
   /** WindowEvent handlers */
   // Called back upon clicking close-window button
   @Override
   public void windowClosing(WindowEvent e) {
      System.exit(0);  // Terminate the program
   }
 
   // Not Used, but need to provide an empty body
   @Override
   public void windowOpened(WindowEvent e) { }
   @Override
   public void windowClosed(WindowEvent e) { }
   @Override
   public void windowIconified(WindowEvent e) { }
   @Override
   public void windowDeiconified(WindowEvent e) { }
   @Override
   public void windowActivated(WindowEvent e) { }
   @Override
   public void windowDeactivated(WindowEvent e) { }
}