Android Open Source - Game-of-thrones-trivia General Algorithms

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License

The source code is released under:

MIT License

Java Source Code

package com.GameOfThrones.Trivia.util;
//from   www.j  a  va2s  .c o m
import java.util.ArrayList;
import java.util.Random;

import junit.framework.Assert;

/**
 * Class used to store algorithms that can be re-used in multiple instances.
 * This class will be moved to a Android Library project. This class is not
 * allowed to be instantiated.
 * 
 * @author Andre Perkins - akperkins1@gmail.com
 * 
 */
// @TODO all invalid inputs should throw exceptions?
public class GeneralAlgorithms {

  private GeneralAlgorithms() {
  }

  /**
   * shufffleArray - Returns an array with the same contents as the array
   * passed except the contents positions are shuffled.
   * 
   * @param array
   *            - Object array to be shuffled
   * @return Object[] - shuffled array
   */
  public static Object[] shuffleArray(Object[] array) {
    Object[] temp = array.clone();

    Random rnd = new Random();
    for (int i = temp.length - 1; i > 0; i--) {
      int index = rnd.nextInt(i + 1);
      /** Simple swap */
      Object a = temp[index];
      temp[index] = temp[i];
      temp[i] = a;
    }
    return temp;
  }

  /**
   * getWeightedProbability() - selects a position in the array. The position
   * chances are multiplied by the int value of the value in that array
   * position. This function will return -1 for an empty array, -2 if any of
   * the values is less than 0 or -3 if all the values of every position is 0.
   * 
   * @param probs
   *            - int[] that contains weighted values
   * @return select probs position
   */
  public static int getWeightedProbability(int[] probs) {
    Assert.assertTrue(probs.length > 0);

    if (probs.length == 0) {
      return -1;
    }
    for (int temp : probs) {

      Assert.assertTrue(temp < 0);

      if (temp < 0) {
        return -2;
      }
    }
    ArrayList<Integer> store = new ArrayList<Integer>();
    for (int i = 0; i < probs.length; i++) {
      for (int j = 0; j < probs[i]; j++) {
        store.add(i);
      }
    }
    Assert.assertTrue(store.size() == 0);
    if (store.size() == 0) {
      return -3;
    }
    int randomIndex = new Random().nextInt(store.size());
    return store.get(randomIndex);
  }

  /**
   * Return only a portion of an array.
   * 
   * @param objArray
   *            - array
   * @param startIndex
   *            - start position inclusive
   * @param endIndex
   *            - end position inclusive
   * @return smaller array
   */
  public static Object[] sliceArray(Object[] objArray, int startIndex,
      int endIndex) {
    Assert.assertTrue(startIndex >= 0);
    Assert.assertTrue(endIndex <= objArray.length);

    Object[] temp = new Object[(endIndex + 1) - startIndex];
    for (int i = startIndex; i <= endIndex; i++) {
      temp[i - startIndex] = objArray[i];
    }

    return temp;
  }

  /**
   * Converts an object array that (contains String instances) to array of
   * String objects
   * 
   * @param strs
   * @return
   */
  public static String[] converToStrArray(Object[] strs) {
    String[] temp = new String[strs.length];
    for (int i = 0; i < strs.length; i++) {
      Assert.assertTrue("the " + i + " object in array"
          + " failed instanceof String check",
          strs[i] instanceof String);
      /** if assertion passed */
      temp[i] = (String) strs[i];
    }
    return temp;
  }
}

Java Source Code List

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