为什么我的代码执行了两次paintComponent(Graphics page)? [英] why is my code executing paintComponent(Graphics page) twice?

问题描述

这让我很紧张，这对我来说可能有些愚蠢，但我不明白为什么我的paintComponent 被调用了两次，如果你运行我的代码，它会输出 REPEAT?重复?两次，我不希望它这样做.. 那么它为什么会这样做，我该如何解决呢?

This is getting on my nerves and it probably something silly on my part but I can't figure out why my paintComponent is being called twice, if you run my code it outputs REPEAT? REPEAT? twice, I don't want it to do that.. So why does it do it and how can I fix it?

import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.*;

public class Main extends JPanel {


    public Main()
    {      
     /*code here*/
    }

    public void paintComponent(Graphics page)
    {
     clear(page);

        /*code here*/

        System.out.println("REpEAT?"); 

    }

    protected void clear(Graphics page) {
        super.paintComponent(page);
      }

    public static void main (String[] args)
    {
        JFrame frame = new JFrame ("Circles");
        frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 200);
        frame.getContentPane().add(new Main());
        frame.setVisible(true);

    }



}

推荐答案

我也打印了两次.

但是，我认为这不必担心.Swing 决定何时需要重新粉刷.例如，如果您调整窗口大小或最小化/最大化，Swing 将重新绘制.它可能取决于您运行的操作系统/硬件.

However, I don't think it is cause for concern. Swing decides when things need to be repainted. For example, if you resize a window or minimise/maximise, Swing will repaint. It might be dependent on the OS/hardware you are running on.

您应该编写代码，使其足够健壮以处理对 repaint 的多次调用.

You should write your code so that it is robust enough to handle multiple calls to repaint.

请也查看这个 SO 问题:paintComponent 正在执行两次

Please see this SO question too: paintComponent is executing twice

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