阶段 2 Part 3 设计文档

You are asked to create a class called Jumper. This actor can move forward two cells in each move. It “jumps” over rocks and flowers. It does not leave anything behind it when it jumps.

1. Inception: clarify the details of the problem:

   a. What will a jumper do if the location in front of it is empty, but the location two cells in front contains a flower or a rock?

   jumper 只向前移动 1 格。

   public void move()
       {
        ...
   		Location loc = getLocation();
        /*
            * get location in front
         */
           Location next = loc.getAdjacentLocation(getDirection());
        /*
            * get location 2 cells in front
         */
           Location next2 = next.getAdjacentLocation(getDirection());
        ...
           	Actor neighbor2 = gr.get(next2);
        	/*
           	 * if location next2 is empty
        	 * move to next2
           	 */
        	if(neighbor2 == null)
           		moveTo(next2);
        	/*
           	 * if location next2 is occupied but jumper can move
        	 * which means next location must be empty
           	 * move to next location
        	 */
           	else moveTo(next);
           ...
       }
   

   b. What will a jumper do if the location two cells in front of the jumper is out of the grid?

   检查 jumper 前 1 格是否在 grid 中、是否为空，若是，jumper 只向前移动 1 格；否则，调用 removeSelfFromGrid 方法将 jumper 从 grid 中移除。

   	public void move()
       {	
   		...
           /*
            * if location 2 cells in front is valid
            * which means next location must be valid
            */
           if (gr.isValid(next2)) {
           	...
           }
           else if (gr.isValid(next))
           	moveTo(next);
           else
               removeSelfFromGrid();
           ...
       }
   

   c. What will a jumper do if it is facing an edge of the grid?

   jumper 顺时针旋转 45 度。

   	/**
        * Moves if it can move, turns otherwise.
        */
       public void act()
       {
           if (canMove())
               move();
           else
               turn();
       }
   
   	public boolean canMove()
       {
           ...
           // if jumper is facing an edge of the grid
           if (!gr.isValid(next))
               return false;
           ...
   }
   

   d. What will a jumper do if another actor (not a flower or a rock) is in the cell that is two cells in front of the jumper?

   • 若 jumper 前 1 格为空，与 a 相同，jumper 只向前移动 1 格；

     	public void move()
         {
             ...
     			Actor neighbor2 = gr.get(next2);
             	/*
             	 * if location next2 is empty
             	 * move to next2
             	 */
             	if(neighbor2 == null)
             		moveTo(next2);
             	/*
             	 * if location next2 is occupied but jumper can move
             	 * which means next location must be empty
             	 * move to next location
             	 */
             	else moveTo(next);
             ...
         }
     

   • 若 jumper 前 1 格被占领，与 c 相似，jumper 转向。

     	public boolean canMove()
         {
             ...
             Actor neighbor2 = gr.get(next2);
             /*
              *  if the location two cells in front of the jumper is occupied
              *  check if next location is empty
              */
             if(neighbor2 != null) {
             	return (neighbor == null);
             }
             ...
     }
     

   e. What will a jumper do if it encounters another jumper in its path?

   jumper 顺时针旋转 45 度。

   	public boolean canMove()
       {
           ...
           if(neighbor2 != null) {
           	return (neighbor == null);
           }
           else {
           	/*
           	 * if next location occupied by an Actor, turn
           	 * else jump
           	 */
           	if(neighbor != null && neighbor instanceof Jumper) {
           		return false;
           	}
           	return true;
           }
       }
   

   f. Are there any other tests the jumper needs to make?

   无。