shark.java

Java程序设计技巧与开发实例附书源代码。

import java.awt.*;

public class Shark
{
    private Polygon fin = new Polygon(new int[]
                                      {0, 0, 30}
                                      ,
                                      new int[]
                                      {60, 30, 60}
                                      , 3);
    private SharkAttack applet = null;
    private int deltaX = 4;

    public Shark(SharkAttack _applet)
    {
        applet = _applet;
    }

    public void moveUp()
    {
        fin.translate(0, -6);
    }

    public void moveDown()
    {
        fin.translate(0, 6);
    }

    public void turnLeft()
    {
        fin.xpoints[1] = fin.xpoints[2];
        deltaX = -Math.abs(deltaX);
    }

    public void turnRight()
    {
        fin.xpoints[1] = fin.xpoints[0];
        deltaX = Math.abs(deltaX);
    }

    public void dive()
    {
        if ( (fin.ypoints[2] - fin.ypoints[1]) > 0)
        {
            if (deltaX > 0)
            {
                fin.xpoints[2] -= 5;
            }
            else
            {
                fin.xpoints[0] += 5;
            }
            fin.ypoints[1] += 5;
        }
    }

    public void rise()
    {
        if ( (fin.ypoints[2] - fin.ypoints[1]) < 40)
        {
            if (deltaX > 0)
            {
                fin.xpoints[2] += 5;
            }
            else
            {
                fin.xpoints[0] -= 5;
            }
            fin.ypoints[1] -= 5;
        }
    }

    public void move()
    {
        if (fin.xpoints[0] > applet.getSize().width)
        {
            turnLeft();
        }
        if (fin.xpoints[0] < 0)
        {
            turnRight();
        }
        fin.translate(deltaX, 0);
    }

    public Point getTip()
    {
        if ( (fin.ypoints[2] - fin.ypoints[1]) < 4)
        {
            return new Point(fin.xpoints[1], fin.ypoints[1]);
        }
        else
        {
            return new Point( -1, -1);
        }
    }

    public void paintComponent(Graphics g)
    {
        g.setColor(Color.lightGray);
        g.fillPolygon(fin);
    }
}