import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.border.Border;

public class ChickenProgram extends JFrame implements ActionListener {

private static final long serialVersionUID = 1L;
private static final int PRICE_PER_COCK = 5; // 公鸡5元钱一只
private static final int PRICE_PER_HEN = 3; // 母鸡3元钱一只
private static final int PRICE_THREE_CHICKENS = 1; // 小鸡1元钱三只
private static final double TOTAL_MONEY = 100;
private static final int NO_OF_CHOOKS = 100; // 总的鸡数量
JPanel panel1, panel2;
JLabel resultLabel;

public ChickenProgram() {
        Container contentPane = getContentPane();
        contentPane.setLayout(new BorderLayout());
        panel1=new JPanel();
        panel1.setLayout(new GridLayout(1,3));
        panel2=new JPanel();
        panel2.setLayout(new BorderLayout());

        JLabel cockLabel, henLabel, chickenLabel;
        cockLabel = new JLabel("每只公鸡：" + PRICE_PER_COCK + "元");
        henLabel = new JLabel("每只母鸡：" + PRICE_PER_HEN + "元");
        chickenLabel = new JLabel("小鸡：" + PRICE_THREE_CHICKENS + "元钱三只");

        JButton calculateButton = new JButton("解答");
        calculateButton.addActionListener(this);
        JPanel smallPanel=new JPanel();
        smallPanel.add(calculateButton);
        JButton exitButton=new JButton("退出");
        smallPanel.add(exitButton);
        exitButton.addActionListener(new ActionListener(){
         public void actionPerformed(ActionEvent e){
          System.exit(0);
         }
        });

        String question = "问题："+TOTAL_MONEY + "元钱买" + NO_OF_CHOOKS
            + "只鸡，问公鸡、母鸡、小鸡各买多少只？";
        JLabel questionLabel = new JLabel(question);
        Border border1=BorderFactory.createTitledBorder("鸡的价格");
        Border border2=BorderFactory.createTitledBorder(question);
        resultLabel = new JLabel("");

        panel1.add(cockLabel);
        panel1.add(henLabel);
        panel1.add(chickenLabel);
        panel1.setBorder(border1);

        panel2.setBorder(border2);
// panel2.add(questionLabel);
        panel2.add(smallPanel,BorderLayout.SOUTH);
        panel2.add(resultLabel);
        contentPane.add(panel1,BorderLayout.NORTH);
        contentPane.add(panel2,BorderLayout.CENTER);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

public static void main(String args[]) {
        ChickenProgram frame = new ChickenProgram();
        frame.setTitle("百钱买百鸡问题");
        frame.setVisible(true);
        frame.setSize(500, 300);
}

public void actionPerformed(ActionEvent e) {

        String resultString = "<html>以下是几种可行方案：<ul>";
        int noOfcocks, noOfHens, noOfchickens;

        for (noOfcocks = 0; noOfcocks <= TOTAL_MONEY / PRICE_PER_COCK; noOfcocks++) {
         for (noOfHens = 0; noOfHens <= TOTAL_MONEY / PRICE_PER_HEN; noOfHens++) {
          noOfchickens = NO_OF_CHOOKS - noOfcocks - noOfHens;
          if (PRICE_PER_COCK * noOfcocks + PRICE_PER_HEN * noOfHens
            + noOfchickens * (PRICE_THREE_CHICKENS / 3.0) == TOTAL_MONEY){
           resultString += ("<li>公鸡-->" + noOfcocks + " 母鸡-->" + noOfHens
             + " 小鸡-->" + noOfchickens+"</li>");
          }
          resultLabel.setText(resultString+"</ul></html>");
         }
        }

}
}