grid.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.
 */

package SimFrameWork ;
import java.util.List ;
import java.util.ArrayList ;
/**
 *  Abstract Grid class representing a generic world. This class is
 *  written so that it does not depend on any particular simulation.
 *  Note that the class is dependent on abstract methods that must be
 *  overridden by subclasses to plug in the specific behaviour for a
 *  particular simulation.
 *
 *  @version 2.0 March 1999
 *  @author Graham Roberts
 */
public abstract class Grid {
  /**
   * Create a grid of given size using patches
   * supplied by a factory object.
   *
   * @param x width of grid in patches
   * @param y height of grid in patches
   * @param f factory object to be used to create patches
   * @param d display object used to display grid.
   */
  public Grid(int x, int y, Factory f, Display d) {
    sizex = x ;
    sizey = y ;
    factory = f ;
    display = d ;
    turtles = new ArrayList() ;
    patches = new Patch[y][x] ;
    // Create all the patches
    for (int i = 0 ; i < sizey ; ++i) {
       for (int j = 0 ; j < sizex ; ++j) {
         // Use the factory to create patches without
         // having to specify the concrete patch type
         // used.
         patches[i][j] = factory.createPatch() ;
       }
    }
    // Connect all the patches together.
    linkPatches() ;
    // Now add turtles to grid.
    createTurtles() ;
  }
  /**
   *  Move the simulated world through 100 time steps, to allow the
   *  simulation to move forward at a reasonable speed. At some
   *  point this should be modified to allow the number of steps to
   *  be changed by the users.
   */
  public final void step() {
    for (int i = 0 ; i < 100 ; ++i) {
      count++ ;
      update() ;
    }
    // When the update is completed, redisplay the grid.
    output() ;
  }
  /**
   *  Return number of timesteps completed.
   */
  public int getTimeCount() {
    return count ;
  }
  /**
   *  Output grid representation to display.  Must be
   *  overridden as this class has no knowledge of how grids are
   *  actually displayed.
   */
  public abstract void output() ;
  /**
   *  Update grid one time step.
   */
  public abstract void update() ;
  /**
   *  Create turtles and add to patches on grid.  This version
   *  completely delegates to a subclass.
   */
  public abstract void createTurtles() ;
  /**
   * Link patches to their neighbours.
   */
  private void linkPatches() {
    for (int i = 0 ; i < sizey ; ++i) {
      for (int j = 0 ; j < sizex ; ++j) {
        Patch patch = patches[i][j] ;
        if (i > 0) {
          patch.setNeighbour(Patch.S,patches[i-1][j]) ;
          if (j > 0) {
            patch.setNeighbour(Patch.SW,patches[i-1][j-1]) ;
          }
          if (j < (sizex-1)) {
            patch.setNeighbour(Patch.SE,patches[i-1][j+1]) ;
          }
        }
        if (j > 0) {
          patch.setNeighbour(Patch.W,patches[i][j-1]) ;
        }
        if (j < (sizex-1)) {
          patch.setNeighbour(Patch.E,patches[i][j+1]) ;
        }
        if (i < (sizey-1)) {
          patch.setNeighbour(Patch.N,patches[i+1][j]) ;
          if (j > 0) {
            patch.setNeighbour(Patch.NW,patches[i+1][j-1]) ;
          }
          if (j < (sizex-1)) {
            patch.setNeighbour(Patch.NE,patches[i+1][j+1]) ;
          }
        }
      }
    }
  }
  /**
   *  Width of grid in patches.
   */
  protected int sizex ;
  /**
   *  Height of grid in patches.
   */
  protected int sizey ;
  /**
   * Count of the number of time steps.
   */
  protected int count = 0 ;
  /**
   *  Factory to be used to create turtles and patches.
   */
  protected Factory factory ;
  /**
   *  2D array of patches in the grid.  Using an array as once
   *  connected, patches remain fixed in position.
   */
  protected Patch[][] patches ;
  /**
   *  Collection of all turtles on the grid.
   */
  protected List turtles ;
  /**
   *  Display object used to render grid on.
   */
  protected Display display ;
}