Android Open Source - noughts-and-crosses-android Computer Player

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License

The source code is released under:

MIT License

Java Source Code

package com.JamesWhite.NoughtsAndCrosses;
/* ww  w .j a v  a 2 s . c om*/
/**
 * 
 * ComputerPlayer
 * 
 * @author James White
 * 
 * Handles the core of the game's AI
 * 
 */

import java.util.Arrays;
import java.util.Collections;

import android.app.AlertDialog;
import android.os.Handler;
import android.widget.TextView;
import android.widget.Toast;

public class ComputerPlayer extends Player {
  /**
   * getNextMove Calculate the next move for the computer using a simple
   * algorithm
   * 
   * @param gridValues
   * @return nextMove
   * @author James White
   */
  public int getNextMove(int[] gridValues) {

    // 8 1 6
    // 3 5 7
    // 4 9 2

    // All the possible two in a row combitnations
    String[] twoInARowPatterns = { "8,1", "1,6", "3,5", "5,7", "4,9",
        "9,2", "8,3", "3,4", "1,5", "5,9", "6,7", "7,2", "8,5", "5,2",
        "6,5", "5,4", "6,2", "8,6", "8,4", "6,4", "8,2", "9,1", "2,4",
        "3,7" };

    // Shuffle it!
    Collections.shuffle(Arrays.asList(twoInARowPatterns));

    // First look if the game can be won by the CPU
    for (String pattern : twoInARowPatterns) {

      String patternParts[] = pattern.split(",");

      int patternPart1 = Integer.parseInt(patternParts[0]);
      int patternPart2 = Integer.parseInt(patternParts[1]);

      int placeToGo = 15 - (patternPart1 + patternPart2);

      if (gridValues[patternPart1 - 1] == super.getType()
          && gridValues[patternPart2 - 1] == super.getType()
          && gridValues[placeToGo - 1] == 0) {

        return placeToGo;

      }

    }

    // Then look to see if we need to defend against any possible winning
    // moves
    for (String pattern : twoInARowPatterns) {

      String patternParts[] = pattern.split(",");

      int patternPart1 = Integer.parseInt(patternParts[0]);
      int patternPart2 = Integer.parseInt(patternParts[1]);

      int placeToGo = 15 - (patternPart1 + patternPart2);

      if (gridValues[patternPart1 - 1] == (-1 * super.getType())
          && gridValues[patternPart2 - 1] == (-1 * super.getType())
          && gridValues[placeToGo - 1] == 0) {

        return placeToGo;

      }

    }

    // Didn't get time to finish this part of the AI, but it would in theory
    // allow the CPU to not only make defensive and finish moves but also to
    // set up it's own attacks! The idea being it would analyse the
    // surrounding positions if it didn't have a move to block/finish and
    // pick somewhere that will give it two an arrow and therefore a chance
    // of wining

    // If we can't block a winning move or make one of our own at least go
    // somewhere that's vaguely useful! i.e somewhere that could lead to a
    // win
    // String[] surroundingPositions = { "8,6,5", "7,5,9", "8,5,4", "3,5,9",
    // "8,1,6,7,2,9,4", "1,5,7", "6,5,2", "1,5,3", "4,5,2" };
    //
    // for (int i = 0; i < gridValues.length; i++) {
    //
    //     if (gridValues[i] == super.getType()) {
    //
    //       String surroundingPosition[] = surroundingPositions[i]
    //         .split(",");
    //
    //       // Shuffle it!
    //       Collections.shuffle(Arrays.asList(surroundingPosition));
    //
    //       for (String position : surroundingPosition) {
    //
    //         int positionInt = Integer.parseInt(position);
    //
    //         if (gridValues[positionInt - 1] == 0) {
    //
    //           return positionInt;
    //
    //         }
    //
    //       }
    //
    //     }
    //
    // }

    // If neither of the above are relevant, go somewhere random
    int nextMove;
    
    do {

      nextMove = (int) Math.round(Math.random() * 8);

    }
    
    // Keep going until we find a position that isn't occupied
    while (gridValues[nextMove] != 0);

    return (nextMove + 1);

  }
}

Java Source Code List

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