GameOfLife/src/Life.java

import java.util.Arrays;

public class Life implements ILife {

  String[] lifeArray;

  public static void main(String[] args) {
    Life l = new Life(new String[] {  "     ",
            "     ",
            " *** ",
            "     ",
            "     " });
    l = (Life) l.nextGeneration();
  }


  public Life() { nukeAll(); }

  public Life(String[] setup) {
    this();
    for (int y = 0; y < setup.length; y++)
      for (int x = 0; x < setup[y].length(); x++)
        if (setup[y].charAt(x) != ' ')
          setAlive(x, y);
  }


  @Override
  public void nukeAll() {
    // TODO Auto-generated method stub
    lifeArray = new String[] { "     ",
            "     ",
            "     ",
            "     ",
            "     "};
  }

  @Override
  public void setAlive(int x, int y) {
    // TODO Auto-generated method stub
    String newString = "";

    newString = lifeArray[y].substring(0, x) + "*" + lifeArray[y].substring(x);

    lifeArray[y] = newString;


  }

  @Override
  public void setDead(int x, int y) {
    // TODO Auto-generated method stub
    String newString = "";

    newString = lifeArray[y].substring(0, x) + " " + lifeArray[y].substring(x);

    lifeArray[y] = newString;

  }

  @Override
  public boolean isAlive(int x, int y) {
    // TODO Auto-generated method stub
    if(lifeArray[y].charAt(x) == '*')
      return true;
    return false;
  }

  @Override
  public ILife nextGeneration() {
    // TODO Auto-generated method stub
    Life newLife = new Life();
    for(int y = 0; y < lifeArray.length; y++) {
      for(int x = 0; x < lifeArray[y].length(); x++) {
        int neighbors = countNeighbors(x, y);

        writeNewGen(neighbors, newLife, x, y);
      }
    }

    return newLife;
  }

  private void writeNewGen(int neighbors, Life newLife, int x, int y) {

    //if the space is alive...
    if(isAlive(x, y)) {

      //...and has more than three or less than two neighbors, it dies
      if (neighbors > 3 || neighbors < 2)
        newLife.setDead(x, y);

      //...and has 2 to 3 neighbors, it survives
      if (neighbors == 3 || neighbors == 2)
        newLife.setAlive(x, y);
    }

    //if the space is dead...
    if(!isAlive(x, y)) {

      //and has 3 neighbors, it comes to life
      if (neighbors == 3) {
        newLife.setAlive(x, y);
      } else {
        //and has anything but 3 neighbors, it stays dead
        newLife.setDead(x, y);
      }
    }
  }

  private int countNeighbors(int x, int y) {
    int counter = 0;

    //count three above
    counter += countAbove(x, y);

    //count three below
    counter += countBelow(x, y);

    //count two sides
    counter += countSides(x, y);

    return counter;
  }

  private int countSides(int x, int y) {
    int counter = 0;

    //is the space left us within the playing field and alive?
    if(x-1 >= 0 && isAlive(x-1, y))
      counter++;

    //is the space right us within the playing field and alive?
    if(x+1 < lifeArray[y].length() && isAlive(x+1, y))
      counter++;

    return counter;
  }

  private int countBelow(int x, int y) {
    int counter = 0;

    //is the line below us within the playing field?
    if(y+1 < lifeArray.length) {
      for (int i = x-1; i <= x+1; i++) {

        //are the spaces on our left, middle and right bottom within the playing field alive?
        if (i >= 0 && i < lifeArray[y+1].length() && isAlive(i, y + 1))
          counter++;
      }
    }
    return counter;
  }

  private int countAbove(int x, int y) {
    int counter = 0;

    //is the line above us within the playing field?
    if(y-1 >= 0) {
      for (int i = x-1; i <= x+1; i++) {

        //are the spaces on our left, middle and right top within the playing field alive?
        if (i >= 0 && i < lifeArray[y-1].length() && isAlive(i, y - 1))
          counter++;
      }
    }
    return counter;
  }

  public void showBoard() {
    for(int y = 0; y < lifeArray.length-1; y++)
      System.out.println(Arrays.toString(new String[] {lifeArray[y]}));
  }
}