java - 尽管我已经编写了frame.repaint()来从循环中调用paintComponent()方法，为什么仍观察到球的运动

Question

import javax.swing.*;
import java.awt.*;

import java.awt.event.*;

class JAnimation implements ActionListener

{

JFrame frame;

int x=40,y=40;

public static void main(String args[])

{

new JAnimation().go(); 

}

 public void go()

 {

  frame=new JFrame();

  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

  JButton button=new JButton("CLICK TO START ANIMATION");

  button.addActionListener(this);

  MyDrawPanel panel=new MyDrawPanel();

  frame.getContentPane().add(BorderLayout.SOUTH,button);

  frame.getContentPane().add(BorderLayout.CENTER,panel);

  frame.setSize(300,300);

  frame.setVisible(true);

 }

  public void actionPerformed(ActionEvent e1)

  {

  System.out.println("INDIA")

  for(int i=0;i<130;i++)

  {

    x++;

    y++; 

    frame.repaint();

    try

   {

    Thread.sleep(50);

   }

   catch(Exception e)

   {

    System.out.println(e);

   }

  }


}

class MyDrawPanel extends JPanel

{

 public void paintComponent(Graphics g1)

 {

  System.out.println("HII");

  Graphics2D g2=(Graphics2D)g1;

  g2.setColor(Color.white);

  g2.fillOval(0,0,this.getWidth(),this.getHeight());

  g2.setColor(Color.green);

  g2.fillOval(x,y,70,70);

  System.out.println(x);

 }

}
}

Answer 1

您正在阻塞 EDT 线程，因为该面板未更新。您卡住了 gui。您可以使用 Swing 计时器而不是线程来制作圆圈动画，而不会阻塞 EDT。阅读swing concurrency .

这是示例

  public void actionPerformed(ActionEvent e1) {

        System.out.println("INDIA");

        new Timer(50, new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent ae) {
                x++;

                y++;

                frame.repaint();
            }
        }).start();

    }