package com.y;import java.awt.*;import java.awt.event.*;import javax.swing.*; public class Test extends JFrame implements ActionListener{    JPanel panel   =new JPanel();    JButton b1     =new JButton("1");    JButton b2     =new JButton("2");    JButton b3     =new JButton(".");    JLabel  lbl    =new JLabel("我是标签");    JTextField txt =new JTextField("",10);    public Test(){        this.setLayout(new FlowLayout());        panel.add(b1);panel.add(b2);panel.add(b3);panel.add(lbl);panel.add(txt);        this.add(panel);        b1.addActionListener(this);        b2.addActionListener(this);        b3.addActionListener(this);    }    public static void main(String[] args) {        Test test=new Test();        test.setSize(400,260);        test.setLocationRelativeTo(null);        test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        test.setVisible(true);    }    @Override    public void actionPerformed(ActionEvent ae) {        txt.setText( txt.getText() + ae.getActionCommand() );    }}