如果鼠标静止不动，Java Canvas的fps将降低

Question

If I'm not somehow updating the screen, several calls to canvas.repaint() seem to be just skipped altogether. While moving the mouse, everything works great.

My code is as follows:

package yeet.gfxTut;

import java.awt.Canvas;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.Random;

import javax.swing.JFrame;

public class Toot extends Canvas {
    private static final long serialVersionUID = 1L;
    public static int xPos, yPos, yV, xV;

    public static void main(String[] args) throws InterruptedException {
        Random rand = new Random();
        JFrame frame = new JFrame("My Drawing");
        Canvas canvas = new Toot();
        canvas.setSize(400, 400);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.add(canvas);
        frame.pack();
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        canvas.addMouseListener(new Toot().new TootMListener());
        xPos = rand.nextInt(400);
        yPos = rand.nextInt(400);
        xV = rand.nextInt(5) + 1;
        yV = rand.nextInt(5) + 1;
        while (true) {
            Thread.sleep(1000 / 60);
            canvas.repaint();
        }
    }

    public void paint(Graphics g) {
        Random rand = new Random();
        if (xPos < 0) {
            xV += rand.nextInt(2) - 1;
            xV = 0 - xV;
        }
        if (yPos < 0) {
            yV += rand.nextInt(2) - 1;
            yV = 0 - yV;
        }
        if (xPos > 400) {
            xV += rand.nextInt(2) - 1;
            xV = 0 - xV;
        }
        if (yPos > 400) {
            yV += rand.nextInt(2) - 1;
            yV = 0 - yV;
        }
        xPos += xV;
        yPos += yV;
        g.fillOval(xPos, yPos, 6, 6);
    }

    private class TootMListener implements MouseListener {
        Random rand = new Random();

        @Override
        public void mouseClicked(MouseEvent e) {
            xV = rand.nextInt(5) + 1;
            yV = rand.nextInt(5) + 1;
        }

        @Override
        public void mousePressed(MouseEvent e) {

        }

        @Override
        public void mouseReleased(MouseEvent e) {

        }

        @Override
        public void mouseEntered(MouseEvent e) {

        }

        @Override
        public void mouseExited(MouseEvent e) {

        }

    }
}

I've had this issue on multiple different canvas projects, any help?

UPDATE: I tried to use the suggested answer, and it resulted in the same issue. New code is as follows:

package yeet.gfxTut;

import java.awt.Canvas;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.Random;

import javax.swing.JFrame;
import javax.swing.Timer;

public class Toot extends Canvas implements ActionListener {
    private static final long serialVersionUID = 1L;
    public static int xPos, yPos, yV, xV;

    Timer timer = new Timer(1000/60, this);
    public Toot() {
        super();
        timer.start();
    }
    public static void main(String[] args) throws InterruptedException {
        // timer.start();
        Random rand = new Random();
        JFrame frame = new JFrame("My Drawing");
        Canvas canvas = new Toot();
        canvas.setSize(400, 400);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.add(canvas);
        frame.pack();
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        canvas.addMouseListener(new Toot().new TootMListener());
        xPos = rand.nextInt(400);
        yPos = rand.nextInt(400);
        xV = rand.nextInt(5) + 1;
        yV = rand.nextInt(5) + 1;
        while (true) {
            Thread.sleep(1000 / 60);
            canvas.repaint();
        }
    }

    public void paint(Graphics g) {
        Random rand = new Random();
        if (xPos < 0) {
            xV += rand.nextInt(2) - 1;
            xV = 0 - xV;
        }
        if (yPos < 0) {
            yV += rand.nextInt(2) - 1;
            yV = 0 - yV;
        }
        if (xPos > 400) {
            xV += rand.nextInt(2) - 1;
            xV = 0 - xV;
        }
        if (yPos > 400) {
            yV += rand.nextInt(2) - 1;
            yV = 0 - yV;
        }
        xPos += xV;
        yPos += yV;
        g.fillOval(xPos, yPos, 6, 6);
    }

    private class TootMListener implements MouseListener {
        Random rand = new Random();

        @Override
        public void mouseClicked(MouseEvent e) {
            xV = rand.nextInt(5) + 1;
            yV = rand.nextInt(5) + 1;
        }

        @Override
        public void mousePressed(MouseEvent e) {

        }

        @Override
        public void mouseReleased(MouseEvent e) {

        }

        @Override
        public void mouseEntered(MouseEvent e) {

        }

        @Override
        public void mouseExited(MouseEvent e) {

        }

    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // if(e.getSource() == timer){
            repaint();
        // }
    }
}

Answer 1

Referring to the first code, instead of

while (true) {
    Thread.sleep(1000 / 60);
    canvas.repaint();
}

use the Timer in the Swing package:

new javax.swing.Timer(1000/60,event->canvas.repaint()).start();

I have taken your class and it runs smooth as expected:

public class Toot extends Canvas {
    private static final long serialVersionUID = 1L;
    public static int xPos, yPos, yV, xV;

    public static void main(String[] args) throws InterruptedException {
        Random rand = new Random();
        JFrame frame = new JFrame("My Drawing");
        Canvas canvas = new Toot();
        canvas.setSize(400, 400);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.add(canvas);
        frame.pack();
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        canvas.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                xV = rand.nextInt(5) + 1;
                yV = rand.nextInt(5) + 1;
            }
        });
        xPos = rand.nextInt(400);
        yPos = rand.nextInt(400);
        xV = rand.nextInt(5) + 1;
        yV = rand.nextInt(5) + 1;
        new javax.swing.Timer(1000/60,e->canvas.repaint()).start();
    }

    @Override
    public void paint(Graphics g) {
        Random rand = new Random();
        if (xPos < 0) {
            xV += rand.nextInt(2) - 1;
            xV = Math.abs(xV);
        }
        if (yPos < 0) {
            yV += rand.nextInt(2) - 1;
            yV = Math.abs(yV);
        }
        if (xPos > 400) {
            xV += rand.nextInt(2) - 1;
            xV = - Math.abs(xV);
        }
        if (yPos > 400) {
            yV += rand.nextInt(2) - 1;
            yV = - Math.abs(yV);
        }
        xPos +=xV;
        yPos +=yV;
        g.fillOval(xPos, yPos, 6, 6);
    }
}