Java:在龟兔赛跑小程序中正确显示位置

Question

我目前正在开发一个项目，该项目以 Applet 形式实时显示龟兔赛跑。选择一个随机数字，动物根据该数字要么向前、向后移动，要么根本不移动。我的问题是如何实时看到动物。目前它会在起始位置显示图像，并说明谁获胜。任何关于如何完成这项工作的指示都会很棒。

我的代码:

import java.applet.Applet;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Color;
import java.awt.Font;

public class Project2 extends Applet
{
Image tortoise, hare;
Image scaledTortoise, scaledHare;
final int tortoiseYPos = 50, hareYPos = 400, SQUARE = 20, END = 1200;
int tortoiseXPos = 180, hareXPos = 180;

public void init()
{
    tortoise = getImage(getDocumentBase(), "tortoise.gif");
    hare = getImage(getDocumentBase(), "hare.gif");
    scaledTortoise = tortoise.getScaledInstance(20, 50, Image.SCALE_SMOOTH);
    scaledHare = hare.getScaledInstance(20, 50, Image.SCALE_SMOOTH);
}

public void paint(Graphics field)
{
    drawField(field);
    drawMoves(field);

    field.setFont(new Font("Times New Roman", Font.ITALIC, 72));
    //Display winner when they get to the finish line
    if(tortoiseXPos >= END)
    {
            field.drawString("Tortoise Wins!!", 650, 240);
    }
        else if(hareXPos >= END)
        {
            field.drawString("Hare Wins!!", 650, 240);
    }
}   

public void drawField(Graphics field)
{
    setBackground(Color.green);
    Font f  = new Font("Times New Roman", Font.BOLD, 48);
    field.setFont(f);
    field.drawString("Tortoise", 0, 75);
    field.drawString("Hare", 0, 425);

    //fill alternating black and white rectangles       
    field.setColor(Color.black);
    int x = 180;
    for(int i = 0; i < 50; i++)
    {
        field.fillRect(x, 50, SQUARE, 50);
        field.fillRect(x, 400, SQUARE, 50);
        x += (SQUARE);
    } 


    field.drawImage(scaledTortoise, 180, tortoiseYPos, this);       
    field.drawImage(scaledHare, 180, hareYPos, this);
}

public void drawMoves(Graphics s)
{ 
    while(tortoiseXPos < END && hareXPos < END)
    {
        int move = (int)(Math.random() * 10);
        tortoiseMoves(move); hareMoves(move);
        s.drawImage(scaledTortoise, tortoiseXPos, tortoiseYPos, this);
        s.drawImage(scaledHare, hareXPos, hareYPos, this);
        delay(); delay(); delay();
    }
}
public void tortoiseMoves(int move)
{ //Moves for Tortoise, 180 is start, 1200 is finish
    if(move <= 5)
    {
        tortoiseXPos += (3 * SQUARE);
    }
    else if(move <= 8)
    {
        tortoiseXPos += SQUARE;
    }
    else if(move <= 10)
    {
        tortoiseXPos -= (6 * SQUARE);
    }

    if(tortoiseXPos < 180)
    {
        tortoiseXPos = 180;
    }

    if(tortoiseXPos > END)
    {
        tortoiseXPos = END;
    }

}

public void hareMoves(int move)
{ //Moves for Hare, 180 is start, 1200 is finish
    if(move <= 2)
    {
        hareXPos += (9 * SQUARE);
    }
    else if(move <= 5)
    {
        hareXPos += (SQUARE);
    }
    else if(move <= 6)
    {
        hareXPos -= (12 * SQUARE);
    }
    else if(move <= 8)
    {
        hareXPos -= (2 * SQUARE);
    }
    else if(move <= 10)
    {
        hareXPos = hareXPos;
    }

    if(hareXPos < 180)
    {
        hareXPos = 180;
    }

    if(hareXPos > END)
    {
        hareXPos = END;
    }
}

public void delay()
{
    for(int i = 0; i <= 90000000; i++)
    {
    }
}
}

我应该注意，我不熟悉也不应该使用 java swing，因为我应该只使用 awt。

Answer 1

问题出在你的延迟函数上。输入循环会使小程序继续运行您的代码，并且它没有机会在移动之间呈现显示。如果您允许小程序运行的线程 hibernate ，那么它就有机会在运行时显示。

public void delay()
{
    try {
        Thread.sleep(100);
    } catch (Exception e) {}
}