《Java编程思想第四版》学习笔记37--关于 TextField的ActionListener接收器

//: TextNew.java
// Text fields with Java 1.1 events
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class TextNew extends Applet {
 Button 
 b1 = new Button("Get Text"), 
 b2 = new Button("Set Text");
 TextField 
 t1 = new TextField(30),
 t2 = new TextField(30),
 t3 = new TextField(30);
 String s = new String();
 public void init() {
 b1.addActionListener(new B1());
 b2.addActionListener(new B2());
 t1.addTextListener(new T1());
 t1.addActionListener(new T1A());
 t1.addKeyListener(new T1K());
 add(b1);
 add(b2);
 add(t1);
 add(t2);
 add(t3);
 }
 class T1 implements TextListener {
 public void textValueChanged(TextEvent e) {
 t2.setText(t1.getText());
 }
 }
 class T1A implements ActionListener {
 private int count = 0;
 public void actionPerformed(ActionEvent e) {
 t3.setText("t1 Action Event " + count++);
 }
 }
 class T1K extends KeyAdapter {
 public void keyTyped(KeyEvent e) {
 String ts = t1.getText();
 if(e.getKeyChar() == 
 KeyEvent.VK_BACK_SPACE) {
 // Ensure it's not empty:
 if( ts.length() > 0) {
 ts = ts.substring(0, ts.length() - 1);
 t1.setText(ts);
 }
 } 
 else
 t1.setText(
 t1.getText() +
 Character.toUpperCase(
 e.getKeyChar()));
 t1.setCaretPosition(
 t1.getText().length());
 // Stop regular character from appearing:
 e.consume(); 
 }
 }
 class B1 implements ActionListener {
 public void actionPerformed(ActionEvent e) {
 s = t1.getSelectedText();
 if(s.length() == 0) s = t1.getText();
 t1.setEditable(true);
 }
 }
 class B2 implements ActionListener {
 public void actionPerformed(ActionEvent e) {
 t1.setText("Inserted by Button 2: " + s);
 t1.setEditable(false);
 }
 }
 public static void main(String[] args) {
 TextNew applet = new TextNew();
 Frame aFrame = new Frame("TextNew");
 aFrame.addWindowListener(
 new WindowAdapter() {
 public void windowClosing(WindowEvent e) {
 System.exit(0);
 }
 });
 aFrame.add(applet, BorderLayout.CENTER);
 aFrame.setSize(300,200);
 applet.init();
 applet.start();
 aFrame.setVisible(true);
 }
 } ///:~

                                                                                                                                                     P.416

经测试：该例程中的ActionListener接收器不起作用，注释掉t1.addKeyListener(new T1K());语句后ActionListener接收器才起作用。是不是加上 KeyAdapter后把ActionListener接收器屏蔽了。