簡單例子

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;

public class MyTest extends JFrame implements KeyListener,ActionListener{

private static final long serialVersionUID = -7206058252243611005L;
JPanel pan=new JPanel();
JPanel panbut=new JPanel();
JTextField txt1=new JTextField();
JTextField txt2=new JTextField();
JTextField txt3=new JTextField();

JButton but1=new JButton("測試1");
JButton but2=new JButton("測試2");
JButton but3=new JButton("測試3");


public static void main(String[] args){
MyTest w =new MyTest();
w.setVisible(true);
}

MyTest(){
this.setSize(300,400);
pan.setLayout(new GridLayout(3,2));
pan.add(new JLabel("輸入1"));
pan.add(txt1);
pan.add(new JLabel("輸入2"));
pan.add(txt2);
pan.add(new JLabel("輸入3"));
pan.add(txt3);

panbut.setLayout(new FlowLayout());
panbut.add(but1);
panbut.add(but2);
panbut.add(but3);

this.setLayout(new BorderLayout());
this.add(pan,BorderLayout.CENTER);
this.add(panbut,BorderLayout.SOUTH);

txt1.addKeyListener(this);
txt2.addKeyListener(this);
txt3.addKeyListener(this);
but1.addKeyListener(this);
but2.addKeyListener(this);
but3.addKeyListener(this);

but1.addActionListener(this);
but2.addActionListener(this);
but3.addActionListener(this);
but2.setName("測試2");
}


@Override
public void keyPressed(KeyEvent arg0) {
// TODO Auto-generated method stub
int key= arg0.getKeyCode();
if (key==KeyEvent.VK_ENTER) {
String name=arg0.getComponent().getName();
if (name!=null)
if (arg0.getComponent().getName().equals("測試2")) {
but2.doClick();
return;
}
arg0.getComponent().transferFocus();
}
}


@Override
public void keyReleased(KeyEvent arg0) {
// TODO Auto-generated method stub

}


@Override
public void keyTyped(KeyEvent arg0) {
// TODO Auto-generated method stub

}



@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
String butname=arg0.getActionCommand();
if (butname.equals("測試1")) {
JOptionPane.showMessageDialog(null, "錯誤！", "測試1", JOptionPane.ERROR_MESSAGE);
return;
}
if (butname.equals("測試2")) {
JOptionPane.showMessageDialog(null, "警告！", "測試2", JOptionPane.WARNING_MESSAGE);
return;
}
if (butname.equals("測試3")) {
JOptionPane.showMessageDialog(null, "資訊！", "測試3", JOptionPane.INFORMATION_MESSAGE);
return;
}
}
}