如何使图像优先于 while 循环绘图背景

Question

所以基本上几天来，我一直在尝试找出我用箭头键移动 'Superman' 对象的关键侦听器。这仅在我 /* */ 退出绘制 'moving' 道路的 while 循环时有效。一旦取消注释并且我运行程序，超人就不会移动，我认为这是因为循环优先于图像。我相信我需要帮助处理图像优先级。非常感谢您的帮助。

// The "CPT" class.
import java.applet.*;
import java.awt.*;
import java.awt.Image;
import java.awt.event.*;
import javax.swing.*;
import java.lang.Runnable;
import java.lang.Thread;



public class CPT extends Applet implements KeyListener
{
    // Place instance variables here
    Image myImage;
    int x = 100, y = 200;

    public void init ()
    {

        myImage = getImage (getCodeBase (), "SuperMan.png");
        System.out.println (getCodeBase ());
        addKeyListener (this);
        // Place the body of the initialization method here
    } // init method





    public void paint (Graphics g)
    {




       //Drawing sky
        g.setColor (new Color (150, 150, 254));
        g.fillRect (0, 0, 1000, 500);
        //Drawing floor
        g.setColor (Color.black);
        g.fillRect (0, 500, 1000, 150);
        //Drawing road lines





        //g.fillRect (
        //Drawing Sun
        g.setColor (Color.yellow);
        g.fillOval (800, 50, 75, 75);

        //Drawing Birds
        g.setColor (Color.black);
        g.drawArc (100, 75, 25, 25, 0, 180);
        g.drawArc (125, 75, 25, 25, 0, 180);

        g.drawArc (175, 85, 25, 25, 0, 180);
        g.drawArc (200, 85, 25, 25, 0, 180);

        g.drawArc (250, 65, 25, 25, 0, 180);
        g.drawArc (275, 65, 25, 25, 0, 180);

        //Drawing Smaller Birds

        g.drawArc (125, 55, 15, 15, 0, 180);
        g.drawArc (140, 55, 15, 15, 0, 180);
        while (true)
        {

            g.setColor (Color.black);
            g.fillRect (-30, 575, 80, 25);
            g.fillRect (120, 575, 80, 25);
            g.fillRect (270, 575, 80, 25);
            g.fillRect (420, 575, 80, 25);
            g.fillRect (570, 575, 80, 25);
            g.fillRect (720, 575, 80, 25);
            g.fillRect (870, 575, 80, 25);
            //first blocks
            g.setColor (Color.yellow);
            g.fillRect (50, 575, 80, 25);
            g.fillRect (200, 575, 80, 25);
            g.fillRect (350, 575, 80, 25);
            g.fillRect (500, 575, 80, 25);
            g.fillRect (650, 575, 80, 25);
            g.fillRect (800, 575, 80, 25);
            g.fillRect (950, 575, 80, 25);





            for (int k = 0 ; k < 100000000 ; k++)
                ;
            //second blocks

            g.setColor (Color.black);
            g.fillRect (50, 575, 80, 25);
            g.fillRect (200, 575, 80, 25);
            g.fillRect (350, 575, 80, 25);
            g.fillRect (500, 575, 80, 25);
            g.fillRect (650, 575, 80, 25);
            g.fillRect (800, 575, 80, 25);
            g.fillRect (950, 575, 80, 25);

            g.setColor (Color.orange);
            g.fillRect (10, 575, 80, 25);
            g.fillRect (160, 575, 80, 25);
            g.fillRect (310, 575, 80, 25);
            g.fillRect (460, 575, 80, 25);
            g.fillRect (610, 575, 80, 25);
            g.fillRect (760, 575, 80, 25);
            g.fillRect (910, 575, 80, 25);

            for (int z = 0 ; z < 100000000 ; z++)
                ;


            //third blocks

            g.setColor (Color.black);
            g.fillRect (10, 575, 80, 25);
            g.fillRect (160, 575, 80, 25);
            g.fillRect (310, 575, 80, 25);
            g.fillRect (460, 575, 80, 25);
            g.fillRect (610, 575, 80, 25);
            g.fillRect (760, 575, 80, 25);
            g.fillRect (910, 575, 80, 25);


            g.setColor (Color.yellow);
            g.fillRect (-30, 575, 80, 25);
            g.fillRect (120, 575, 80, 25);
            g.fillRect (270, 575, 80, 25);
            g.fillRect (420, 575, 80, 25);
            g.fillRect (570, 575, 80, 25);
            g.fillRect (720, 575, 80, 25);
            g.fillRect (870, 575, 80, 25);

            for (int t = 0 ; t < 100000000 ; t++)
                ;



            g.drawImage (myImage, x, y, 100, 40, this);

        }
    } // paint method


    public void keyReleased (KeyEvent e)
    {


    }


    public void keyPressed (KeyEvent e)
    {
        if (e.getKeyCode () == KeyEvent.VK_RIGHT)
        {
            // System.out.println ("Right Key Pressed");
            x += 10;
        }

        if (e.getKeyCode () == KeyEvent.VK_LEFT)
        {
            // System.out.println ("Left Key Pressed");
            x -= 10;
        }

        if (e.getKeyCode () == KeyEvent.VK_UP)
        {
        y -= 10;
        }

        if (e.getKeyCode () == KeyEvent.VK_DOWN)
        {
        y+=10;
        }
        repaint ();
    }



    public void keyTyped (KeyEvent e)
    {

    }
} // CPT class

Answer 1

while loop 会冻结您的整个应用程序。它将继续在图形上绘制内容，但不允许 Swing 事件调度线程使用您的图形刷新屏幕。

一些建议：

1) 将 while 循环移出 paint 方法并移至单独的线程中。最好阅读一下如何在 Java Swing 中制作适当的动画。

2) 阅读如何正确覆盖 Swing 组件 paint 方法。

3) 阅读什么是事件调度线程以及为什么必须避免阻塞它。

如何使图像优先于 while 循环绘图背景

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