当我有动画的时候，我如何让对象*不*移动？

Question

在swing图形中，我需要制作一些东西，其中的杆状图形来回移动，但有些东西保持不变。我使用蓝色水平线作为测试。它不会移动，但随着棍形人物的剑，它会及时消失。我怎么才能阻止它？

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class AnimatedBoxman extends JApplet  implements Runnable,ActionListener
{   
   int size=50;

   int x = 0;
   int y =300;
   int side2side = 50;

   Thread t;
   boolean sworddrawn = false;
   JButton myButton = new JButton("Change");
   static Random myRan = new Random();
   public void init()
   {

       Container content = getContentPane();
         content.setBackground(Color.red);
         setLayout(new FlowLayout());
         add(myButton);
         myButton.addActionListener(this);


   }
   public void actionPerformed (ActionEvent ae)
   {
      side2side= -side2side;
     Container content = getContentPane();
     content.setBackground(new Color 
        (Math.abs(myRan.nextInt())%256,
         Math.abs(myRan.nextInt())%256,
         Math.abs(myRan.nextInt())%256));

     repaint();
   }
   public void run( )
   {
     while( true )
     {
      x+= side2side;
      if (x > this.getSize().width-50 || x < 0)
          side2side = -side2side;
      if (x%3 == 0)
          sworddrawn = !sworddrawn;
      repaint( );
      try {
          Thread.sleep(900);
      }
      catch( Exception e ) { }
     }
   }
   public void start( )
   {
    t = new Thread(this);
    t.start( );
   }

   public void paint ( Graphics g )
   {
     super.paint( g );

        g.setColor(Color.blue);
        g.drawLine(x-10, y, x-30,y);
        g.drawLine(x-30, y, x-30, y-20);
        g.drawLine(x-10, y-20, x-10, y);


        g.drawLine(x-10, y-20, x+10, y-20);
        g.drawLine(x-10, y-20, x+10, y-20);
        g.drawLine(x-10, y, x+10, y);
        g.drawLine(x-10, y, x-10, y+20);
        g.drawLine(x, y+20, x, y);
        g.drawLine(x+10, y+20,x+10, y);

        g.drawLine(x+10, y, x+30, y);
        g.drawLine(x+30, y, x+30, y-20);
        g.drawLine(x+10, y-20, x+10, y);

        g.drawLine(x, y+20, x+10, y+20);
        g.drawLine(x-10, y+20, x-10, y+30);
        g.drawLine(x-10, y+30, x, y+30);
        g.drawLine(x, y+30, x, y+20);
        g.drawLine(x, y+30, x+10, y+30);
        g.drawLine(x+10, y+30, x+10, y+20);
        g.drawLine(x-10, y+20, x, y+20);
        g.drawOval(x-7, y-20, 5, 5);
        g.drawOval(x+1, y-20, 5, 5);
        g.drawLine(x-4, y-8, x-5, y-5);
        g.drawLine(x-5, y-8, x+6, y-8);
        g.drawLine(x+6, y-5, x+6, y-8);


     if( sworddrawn )
     {
         g.drawLine(500, 400, 700, 400);
         }
     else
     {


            Polygon myPolygon2;
            myPolygon2=new Polygon();
            myPolygon2.addPoint(x-42,y-184);
            myPolygon2.addPoint(x-32,y-195);
            myPolygon2.addPoint(x-21,y-184);
            g.fillPolygon(myPolygon2);
            g.fillRect(x-41, y-184, 20, 100);
            g.fillArc(x-50, y-104, 40, 20, 180, 180);
            g.fillArc(x-35, y-94, 20, 35, 90, 180);
            g.drawLine(x-30, y-164, x-30, y-24);

            g.drawOval(x-40, y-24, 20, 30);

     }

   }
}

Answer 1

蓝色水平线可以在内容窗格之外，在这种情况下不会绘制它。您可以通过向init方法添加一行来检查内容窗格的大小：

System.out.println("getSize(): " + getSize());

在我的笔记本电脑上，大小是400x300像素：

getSize(): java.awt.Dimension[width=400,height=300]

这会产生一条不可见的蓝色水平线：

g.drawLine(500, 400, 700, 400);

X和y坐标值较低时，该线是可见的：

g.drawLine(50, 40, 70, 40);

最后，当您提出问题时，添加应用程序的屏幕截图和一些额外的文本来解释您的问题是什么(例如，您所期望的与您所看到的相比)可能会很有用。