键盘监控

package aa;
import java.awt.*;
import java.awt.event.*;
public class reMulEvent extends WindowAdapter implements ActionListener{
Frame myFrame;
Label myLabel;
TextField myText;
Button myBtn;
public class myKeyAdapter extends KeyAdapter
{
public void keyPressed(KeyEvent l){

if(l.getKeyChar() < '0' || l.getKeyChar() > '9')
{

myLabel.setText("非数字键");
}
else{
myLabel.setText("数字键");
}

}
}
public reMulEvent(){
myKeyAdapter whatKey = new myKeyAdapter();
myFrame = new Frame("Frame");
myLabel = new Label("Label");
myText = new TextField("请输入内容");
myBtn = new Button("清空内容");

myText.setSize(100,100);
myFrame.add(myLabel);
myFrame.add(myText);
myFrame.add(myBtn);
myFrame.setSize(500,500);
myFrame.setVisible(true);
myFrame.setLayout(new GridLayout(3,1));
myFrame.addWindowListener(this);
myText.addKeyListener(whatKey);
myBtn.addActionListener(this);
}
public void windowClosing(WindowEvent e)
{
myFrame.dispose();
}
public void actionPerformed(ActionEvent e){
if(e.getSource() == myBtn)
myText.setText(null);
}
public static void main(String args[])
{
new reMulEvent();
}
}

和按钮监控不同的是 需要创建内部类public class myKeyAdapter extends KeyAdapter，创建，myKeyAdapter对象x，在addKeyListen(x).