import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;


public class Test extends JFrame {

    private JPanel contentPane;
    private JTextField n1;
    private JTextField n2;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Test frame = new Test();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public Test() {
        setTitle("test");
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 280, 99);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);
        
        n1 = new JTextField();
        n1.setBounds(47, 10, 66, 21);
        contentPane.add(n1);
        n1.setColumns(10);
        
        n2 = new JTextField();
        n2.setBounds(180, 10, 66, 21);
        contentPane.add(n2);
        n2.setColumns(10);
        
        JButton button = new JButton("\u4EA4\u6362");
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                exchange();
            }
        });
        button.setBounds(57, 41, 74, 23);
        contentPane.add(button);
        
        JLabel label = new JLabel("\u6570\u5B571\uFF1A");
        label.setBounds(0, 10, 47, 21);
        contentPane.add(label);
        
        JLabel label_1 = new JLabel("\u6570\u5B572\uFF1A");
        label_1.setBounds(127, 10, 47, 21);
        contentPane.add(label_1);
        
        JButton button_1 = new JButton("\u6E05\u7A7A");
        button_1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                n1.setText("");
                n2.setText("");
            }
        });
        button_1.setBounds(147, 41, 74, 23);
        contentPane.add(button_1);
    }
    
    private void exchange(){
        try {
            int numberInt_1=Integer.parseInt(n1.getText());
            int numberInt_2=Integer.parseInt(n2.getText());
            System.out.println("交换前：\n\t数字一："+numberInt_1+"\n\t数字二："+numberInt_2);
            int temp;
            /*
             * 先交换值，再显示在文本框中。
             * 当然也可以直接显示，不用在顶定义个变量。这样只需
             * n1.setText(""+numberInt_2);
             * n2.setText(""+numberInt_1);
             */
            temp=numberInt_1;
            numberInt_1=numberInt_2;
            numberInt_2=temp;
            System.out.println("交换后：\n\t数字一："+numberInt_1+"\n\t数字二："+numberInt_2);
            n1.setText(""+numberInt_1);
            n2.setText(""+numberInt_2);
        } catch (Exception e) {
            JOptionPane.showMessageDialog(n1, "只能输入数字。");
        }
    }
}