java - 程序不改变颜色

Question

我正在尝试编写一个程序，您可以在其中猜测一个随机生成的数字(从 1 到 1000)，该程序会告诉您是否接近。我遇到的问题是我必须根据您与答案的接近程度改变背景颜色。红色更近，蓝色更远。我有代码，但我不知道为什么后台不工作。这与容器有关吗？谢谢!

 import javax.swing.*;
 import java.awt.event.*;
 import java.awt.*; 
 import java.util.Random;;
 public class GuessGame extends JFrame
 {   
private JButton newGameButton;
private JButton enterButton;
private JButton exitButton;
private JTextField guessBox;
private JLabel initialTextLabel;
private JLabel enterLabel;
private JLabel userMessageLabel;
private int randomNumber;
private int userGuess;
private int counter = 0;
private int lastGuess = 0;
private Color background;
Container container;

public GuessGame()
{
    super("Guessing Game");
    newGameButton = new JButton("New Game");
    exitButton = new JButton("Exit Game");
    enterButton = new JButton("Enter");
    guessBox = new JTextField(4);
    initialTextLabel = new JLabel("I have a number between 1 and 1000 can you guess my number?");
    enterLabel = new JLabel("Please enter your first guess.");
    userMessageLabel = new JLabel("");
    randomNumber = new Random().nextInt(1000) + 1;

    container=getContentPane();
    container.setLayout(new FlowLayout());
    container.add(initialTextLabel);
    container.add(enterLabel);
    container.add(guessBox);
    container.add(newGameButton);
    container.add(enterButton);
    container.add(exitButton);
    container.add(userMessageLabel);

    setSize(400, 150);

    addWindowListener(new WindowAdapter()
    {
        public void windowClosing(WindowEvent e)
        {
            System.exit(0);
        }
    });

    newGameButtonHandler nghandler = new newGameButtonHandler();
    newGameButton.addActionListener(nghandler); 
    ExitButtonHandler exithandler = new ExitButtonHandler();
    exitButton.addActionListener(exithandler);
    enterButtonHandler enterhandler = new enterButtonHandler();
    enterButton.addActionListener(enterhandler);
}

class newGameButtonHandler implements ActionListener
{
    public void actionPerformed(ActionEvent e)
    {
        getContentPane();
        background=Color.lightGray;
        userMessageLabel.setText("");
        randomNumber = new Random().nextInt(1000) + 1;
    }
}

class ExitButtonHandler implements ActionListener
{
    public void actionPerformed(ActionEvent e)
    {
        System.exit(0);
    }
}

class enterButtonHandler implements ActionListener
{
    public void actionPerformed(ActionEvent e)
    {
        userGuess = Integer.parseInt(guessBox.getText());
        compareGuess(userGuess, randomNumber);
    }
}

public void paint(Graphics g)
{
    super.paint(g);
    container.setBackground(background);
}

public void compareGuess(int userGuess, int randomNumber)
{
    counter++;
    if (userGuess == randomNumber)
        {
            userMessageLabel.setText("You are correct, it took you: " + counter + " tries");
            getContentPane();
            background=Color.green;
        }
    else if (userGuess > randomNumber)
        {
            userMessageLabel.setText("Too high");
        }
    else if (userGuess < randomNumber)
        {
            userMessageLabel.setText("Too Low");
        }
    if (counter > 1)
    {
        if ((randomNumber - userGuess) > (randomNumber - lastGuess))
            {
                getContentPane();
                background=Color.red;
            }
        else if ((randomNumber - userGuess) < (randomNumber - lastGuess))
            {
                getContentPane();
                background=Color.blue;
            }
        else
            {
                getContentPane();
                background=Color.gray;
            }
    }
    lastGuess = userGuess;
}
public static void main(String[] args)
{
    GuessGame myGuessGame = new GuessGame();
    myGuessGame.setVisible(true);
}
}

Answer 1

1. 您正在尝试覆盖 JFrame 的 paint(Graphics g) 函数。我们不应该覆盖像 JFrame 这样的顶级组件的绘制函数。

2. 使用自定义组件扩展 JPanel 并覆盖其 paintComponent(Graphics g) 函数，不要忘记调用 super.paintComponent(g ) 在此函数内。

3. 当应该对组件的绘制进行任何更新时，调用该组件上的 component.repaint() 以在 GUI 上反射(reflect)更改。

请浏览官方教程页面:Lesson: Performing Custom Painting