private void updateFish() { 
      // fish update 
      ArrayList<Cell> fishCells = getCellsOfType(board, WaTorRule.FISH_TYPE); 
      for(Cell thisC : fishCells) { 
         WaTorCell thisCell = (WaTorCell) thisC; 
         thisCell.step(); 
         ArrayList<Cell> emptyNeighborCells =  
               this.getCellsOfType(thisCell.getNeighbors(), WaTorRule.EMPTY_TYPE); 
         if(emptyNeighborCells.isEmpty()) // no empty cell 
            continue; 
         WaTorCell targetCell = (WaTorCell) randomAccess(emptyNeighborCells); 

   private void updateShark() { 
      // shark update 
      ArrayList<Cell> sharkCells = getCellsOfType(board, WaTorRule.SHARK_TYPE); 
 
      for(Cell thisC : sharkCells) { 
         WaTorCell thisCell = (WaTorCell) thisC; 
         thisCell.step(); 
         if(thisCell.getValue().getVal()==WaTorRule.EMPTY_TYPE) { 
            continue; 
         } 
         ArrayList<Cell> neighborCells =  
               this.getCellsOfType(thisCell.getNeighbors(), WaTorRule.EMPTY_TYPE); 
         neighborCells.addAll(this.getCellsOfType(thisCell.getNeighbors(), WaTorRule.FISH_TYPE)); 
         if(neighborCells.isEmpty()) { 
            continue; 
         } 
          
         WaTorCell targetCell = (WaTorCell)randomAccess(neighborCells); 

   protected ArrayList<Cell> getCellsOfType(ArrayList<Cell> cellList, int type) { 
      ArrayList<Cell> cells = new ArrayList<Cell>(); 
      for(Cell c : cellList) { 
         if(c.getValue().getVal()==type) { 
            cells.add(c); 
         } 
      } 
      return cells; 
   } 

   private ArrayList<Cell> getUnhappyIdxs(int thisType, int otherType) { 
      ArrayList<Cell> thisTypeCells = this.getCellsOfType(board, thisType); 
      ArrayList<Cell> unhappyCells = new ArrayList<Cell>(); 
      for(Cell c : thisTypeCells) { 
         int numDiff = this.getCellsOfType(c.getNeighbors(), otherType).size(); 
         if(numDiff/(float)NUM_NEIGHBORS < this.satisfactionThreshold) { 
            unhappyCells.add(c); 
         } 
      } 
      return unhappyCells; 
   } 

      Cell[][] boardArr = new Cell[height][width]; 
      // add cell and append rule 
      for(int h=0; h<height; h++) { 
         for(int w=0; w<width; w++) { 

      Cell[][] board = new Cell[height][width]; 
      for(int i=0; i<height; i++) { 
         for(int j=0; j<width; j++) { 

   private void parseFireRule(Document d) { 
      double probCatch = Double.parseDouble(this.getUniqueKey(d, "ProbCatch")); 
      rule = new FireRule(probCatch); 
   } 

   private void parseSegregationRule(Document d) { 
      double threshold = Double.parseDouble(this.getUniqueKey(d, "SatisfactionThreshold")); 
      rule = new SegregationRule(threshold); 
   } 

      this.value.setVal(type); 
      currentHealth = ((WaTorRule)this.rule).getInitialHealth(); 

      this.value.setVal(type); 
      currentHealth = ((WaTorRule)this.rule).getInitialHealth();