antworld.java

一个TSP问题的图形演示程序

/*
 *  This code is from the book:
 *
 *    Winder, R and Roberts, G (2000) Developing Java
 *    Software, second edition, John Wiley & Sons.
 *
 *  It is copyright (c) 2000 Russel Winder and Graham Roberts.
 */

import java.util.List ;
import java.util.Iterator ;
import SimFrameWork.* ;
/**
 *  AntWorld - a specialized grid representing an ant world.
 *
 *  @version 2.0 March 1999
 *  @author Graham Roberts
 */
class AntWorld extends Grid {
  /**
   *  Create a grid specialized for the ant simulation.
   *
   *  @param x width of display in patches.
   *  @param y height of display in patches.
   *  @param d display object to display simulation.
   */
  public AntWorld(int x, int y, Display d) {
    super(x,y,new AntFactory(),d) ;
  }
  /**
   *  Iterate through the grid of patches and output a value for
   *  each patch, using the display object.
   */
  public void output() {
    display.clear() ;
    for (int i = 0 ; i < sizey ; ++i) {
      for (int j = 0 ; j < sizex ; ++j) {
        // Generate a display value for each patch
        Patch patch = patches[i][j] ;
        int patchvalue = patch.value() ;
        List turtles = patch.getTurtles() ;
        int val = 0 ;
        if (patchvalue > 0) {
          val = patchvalue ;
        }
        if (turtles.size() > 0) {
          val = -1 ;
          for (Iterator iter = turtles.iterator() ; 
               iter.hasNext() ; ) {
            Ant ant = (Ant)(iter.next()) ;
            if (ant.isLoaded()) {
              val = -2 ;
              break ;
            }
          }
        }
        // Send the coordinates and value of each patch to the
        // display object.
        display.show(j,i,val) ;
      }
    }
    // Tell the display object that the iteration is complete and
    // that it should go ahead and display the grid.
    display.showGrid() ;
  }
  /**
   *  Call update for one time step on all updatable objects. For
   *  this simulation, only the ants need to be updated.
   */
  public void update() {
    for (Iterator i = turtles.iterator() ; i.hasNext() ;) {
      ((Turtle)i.next()).update() ;
    }
  }
  /**
   *  Allocate ants at random around the grid.
   */
  public void createTurtles() {
    for (int i = 0 ; i < 150 ; ++i) {
      int px =  RandomGen.getNext(sizex) ;
      int py =  RandomGen.getNext(sizey) ;
      Patch p = patches[py][px] ;
      Turtle t = factory.createTurtle(p) ;
      turtles.add(t) ;
      p.addTurtle(t) ;
    }
  }
}