AssignmentGameOfLife/src/Life.java

import java.util.Arrays;

public class Life implements ILife {

  static String[] grid = new String[]{    "*    ",
          "*    ",
          "*    ",
          "     ",
          "     " };

  public static void main(String[] args) {
    Life l = new Life(grid);
    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);
        }
      }
    }

    printTable(grid);
  }

  private void printTable(String[] grid) {
    for(int i = 0; i < grid.length; i++) System.out.println(Arrays.toString(new String[]{grid[i]}));
    System.out.println("________");
  }


  @Override
  public void nukeAll() {
    // TODO Auto-generated method stub
    for (int y = 0; y < grid.length; y++){
      for (int x = 0; x < grid[y].length(); x++) {
        setDead(x, y);
      }
    }
  }

  @Override
  public void setAlive(int x, int y) {
    // TODO Auto-generated method stub
    grid[y] = grid[y].substring(0, x) + '*' + grid[y].substring(x+1);
  }

  @Override
  public void setDead(int x, int y) {
    // TODO Auto-generated method stub
    grid[y] = grid[y].substring(0, x) + ' ' + grid[y].substring(x+1);
  }

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

  @Override
  public ILife nextGeneration() {
    // TODO Auto-generated method stub
    int alive;
    String[] nextGrid = new String[]{  "     ",
            "     ",
            "     ",
            "     ",
            "     " };

    for (int y = 0; y < grid.length; y++){
      for (int x = 0; x < grid[y].length(); x++){
        alive=aliveNeighbourCells(x,y);

        if(!isAlive(x,y) && alive == 3) {
          nextGrid[y] = nextGrid[y].substring(0, x) + '*' + nextGrid[y].substring(x+1);
        }

        else if((isAlive(x,y) && (alive < 2)) || (alive > 3)){
          nextGrid[y] = nextGrid[y].substring(0, x) + ' ' + nextGrid[y].substring(x+1);
        }

        else if(isAlive(x,y) && (alive == 2 || alive == 3)){
          nextGrid[y] = nextGrid[y].substring(0, x) + grid[y].charAt(x) + nextGrid[y].substring(x+1);
        }
      }
    }
    grid = nextGrid;
    return null;
  }

  private int aliveNeighbourCells(int x, int y) {
    int neighbours = 0;

    if(x>0 && y>0){
      if(grid[y-1].charAt(x-1) == '*'){
        neighbours++;
      }
    }
    if(x>0){
      if(grid[y].charAt(x-1) == '*'){
        neighbours++;
      }
      if(y<4 ){
        if(grid[y+1].charAt(x-1) == '*'){
          neighbours++;
        }
      }
    }

    if(y>0){
      if(grid[y-1].charAt(x) == '*'){
        neighbours++;
      }
      if(x<4){
        if(grid[y-1].charAt(x+1) == '*'){
          neighbours++;
        }
      }
    }

    if(x<4){
      if(grid[y].charAt(x+1) == '*'){
        neighbours++;
      }
    }
    if(y<4){
      if(grid[y+1].charAt(x) == '*'){
        neighbours++;
      }
    }
    if(x<4 && y<4){
      if(grid[y+1].charAt(x+1) == '*'){
        neighbours++;
      }
    }
    return neighbours;
  }

}