swing事件处理机制小例子--第二个文本框监视第一个文本框

   这个例子用java编写。在窗体中创建了两个文本框，为第一个文本框添加了按键监听器，文本内容的改变会同步到第二个文本框中。

   注意实现KeyListener这个接口，一定要在里面加上 keyPressed，keyReleased，keyTyped这三个函数，大小写注意，否则会报错。

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;


public class EventDemo extends JFrame {
  private JTextField textField1;
  private JTextField textField2;
  public static void main(String args[]){
	  EventDemo frame = new EventDemo();
	  frame.setVisible(true);
  }
  public EventDemo(){
	  super();
	  getContentPane().setLayout(null);
	  setBounds(100,100,305,113);
	  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	  textField1 = new JTextField();
	  textField1.addKeyListener(new TextKeyListener());
	  textField1.setBounds(115, 12, 172, 22);
	  getContentPane().add(textField1);
	  textField2 = new JTextField();
	  textField2.setBounds(115, 40, 172, 22);
	  getContentPane().add(textField2);
	  final JLabel label = new JLabel();
	  label.setText("the first textfield :");
	  label.setBounds(10,12,99,18);
	  getContentPane().add(label);
	  final JLabel label_1 = new JLabel();
	  label_1.setText("the second textfield :");
	  label_1.setBounds(10,40,99,18);
	  getContentPane().add(label_1);
	  
  }
private final class TextKeyListener implements KeyListener{

  public void keyPressed(KeyEvent e){
		
	}
  public void keyReleased(KeyEvent e){
	String text = textField1.getText();
	textField2.setText(text);
	
  }
  public void keyTyped(KeyEvent e){
	
  }
	
	
}
}