java - 用随机颜色更新小程序

Question

我正在尝试制作一个背景随时间缓慢变化的 JFrame。这是我的代码:

public class RainbowWindow extends Applet implements ActionListener {

    private static final long serialVersionUID = 1L;

    public void paint(Graphics g) {
        Timer timer = new Timer(1000, this);
        timer.start();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        Color color = new Color(((int) Math.random()), ((int) Math.random()), ((int) Math.random()), 255);
        setBackground(color);

    }
}

但我得到的只是黑屏

Answer 1

1. Java Plugin support deprecated和 Moving to a Plugin-Free Web
2. 不要在paint中创建Timer，每次需要绘制组件时都会调用paint，并且通常会快速连续地调用。请参阅Painting in AWT and Swing nd Performing Custom Painting有关 Swing 中绘画工作原理的更多详细信息
3. 您应该避免重写顶级容器(如 JFrame 和 Applet)的 Paint ，它们不是双缓冲的，并且往往会导致问题结束了，最好从某种组件开始并将其添加到您想要的任何容器
4. JFrame != Applet
5. Math.random 返回 0 和 1 之间的值，Color 期望 之间的值0-255

例如

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            Timer timer = new Timer(1000, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    int red = (int)(Math.random() * 255);
                    int green = (int)(Math.random() * 255);
                    int blue = (int)(Math.random() * 255);
                    Color color = new Color(red, green, blue, 255);
                    setBackground(color);
                }
            });
            timer.start();
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }
}