carfield.com.hk

Amaze.txt

2001-12-26T16:00:00Z

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Maze.java

2001-12-26T16:00:00Z

//: c13:Maze.java
import java.util.*;
import java.io.*;
import java.awt.*;

public class Maze extends Canvas {
  private Vector lines; // a line is a char array
  private int width = -1;
  private int height = -1;
  public static void main (String [] args) 
  throws IOException {
    if (args.length < 1) {
      System.out.println("Enter filename");
      System.exit(0);
    }
    Maze m = new Maze();
    m.load(args[0]);
    Frame f = new Frame();
    f.setSize(m.width*20, m.height*20);
    f.add(m);     
    Rat r = new Rat(m, 0, 0);
    f.setVisible(true);
  }
  public Maze() {
    lines = new Vector();
    setBackground(Color.lightGray);
  }
  synchronized public boolean 
  isEmptyXY(int x, int y) {
    if (x < 0) x += width;
    if (y < 0) y += height; 
    // Use mod arithmetic to bring rat in line:
    byte[] by = 
      (byte[])(lines.elementAt(y%height));  
    return by[x%width]==' ';
  }
  synchronized public void 
  setXY(int x, int y, byte newByte) {
    if (x < 0) x += width;
    if (y < 0) y += height; 
    byte[] by = 
      (byte[])(lines.elementAt(y%height));
    by[x%width] = newByte;
    repaint();
  }
  public void 
  load(String filename) throws IOException {
    String currentLine = null;
    BufferedReader br = new BufferedReader(
      new FileReader(filename));
    for(currentLine = br.readLine(); 
        currentLine != null;
        currentLine = br.readLine())  {
      lines.addElement(currentLine.getBytes());       
      if(width < 0 || 
         currentLine.getBytes().length > width)
        width = currentLine.getBytes().length;
    }
    height = lines.size();
    br.close();
  }       
  public void update(Graphics g) { paint(g); }
  public void paint (Graphics g) {
    int canvasHeight = this.getBounds().height;
    int canvasWidth  = this.getBounds().width;
    if (height < 1 || width < 1) 
      return; // nothing to do 
    int width = 
      ((byte[])(lines.elementAt(0))).length;
    for (int y = 0; y < lines.size(); y++) {
      byte[] b;
      b = (byte[])(lines.elementAt(y));
      for (int x = 0; x < width; x++) {
        switch(b[x]) {
          case ' ': // empty part of maze
            g.setColor(Color.lightGray);
            g.fillRect(
              x*(canvasWidth/width),
              y*(canvasHeight/height),
              canvasWidth/width,
              canvasHeight/height);
            break;
          case '*':     // a wall 
            g.setColor(Color.darkGray);
            g.fillRect(
              x*(canvasWidth/width),
              y*(canvasHeight/height),
              (canvasWidth/width)-1,
              (canvasHeight/height)-1);
            break;
          default:      // must be rat
            g.setColor(Color.red);
            g.fillOval(x*(canvasWidth/width),
            y*(canvasHeight/height),
            canvasWidth/width,
            canvasHeight/height);
            break;              
        }      
      }     
    }
  }
} ///:~

Rat.java

2001-12-26T16:00:00Z

//: c13:Rat.java

public class Rat {
  static int ratCount = 0;
  private Maze prison;
  private int vertDir = 0; 
  private int horizDir = 0;
  private int x,y;
  private int myRatNo = 0;
  public Rat(Maze maze, int xStart, int yStart) {
    myRatNo = ratCount++;
    System.out.println("Rat no." + myRatNo + 
      " ready to scurry.");
    prison = maze;
    x = xStart;
    y = yStart;
    prison.setXY(x,y, (byte)'R');
    new Thread() {
      public void run(){ scurry(); }
    }.start();
  }
  public void scurry() {
    // Try and maintain direction if possible.
    // Horizontal backward
    boolean ratCanMove = true;
    while(ratCanMove) {
      ratCanMove = false;
      // South 
      if (prison.isEmptyXY(x, y + 1)) {
        vertDir = 1; horizDir = 0;         
        ratCanMove = true;
      }
      // North
      if (prison.isEmptyXY(x, y - 1))
        if (ratCanMove)
          new Rat(prison, x, y-1);
          // Rat can move already, so give 
          // this choice to the next rat.
        else {
          vertDir = -1; horizDir = 0;         
          ratCanMove = true;
        }
      // West
      if (prison.isEmptyXY(x-1, y))
        if (ratCanMove)
          new Rat(prison, x-1, y);   
          // Rat can move already, so give 
          // this choice to the next rat.
        else {
          vertDir = 0; horizDir = -1;         
          ratCanMove = true;
        }
      // East
      if (prison.isEmptyXY(x+1, y))
        if (ratCanMove)
          new Rat(prison, x+1, y);   
          // Rat can move already, so give 
          // this choice to the next rat.
        else {
          vertDir = 0; horizDir = 1;         
          ratCanMove = true;
        }
      if (ratCanMove) { // Move original rat.
        x += horizDir;
        y += vertDir;
        prison.setXY(x,y,(byte)'R');
      }  // If not then the rat will die.
      try {
        Thread.sleep(2000);   
      } catch(InterruptedException ie) {}
    }
    System.out.println("Rat no." + myRatNo + 
      " can't move..dying..aarrgggh.");
  }
} ///:~

makefile

2001-12-26T16:00:00Z