Position and orientation of robot in a grid

问题

I want to make a 10x10 grid and put the robot in position (10,1) (bottom left). I want this robot to be able to move forward, turn left/right and to pick up/put objects in a grid. When put in any position, there should be number in a grid which shows how many objects is put in this position, just like this:

..........
...1......
..2.......
....3.....
..........
..........
......9...
.....4....
.........1
..........

We will not see the robot in a grid. I have two classes. Class Robot:

public class Robot {

private Area area;
private Robot rob;

public Robot(Area area){
    this.area = area;
    rob = new Robot(area);
}

public void Right(){

}
public void Left(){

}
public void Forward(){

}
public void Put(){

}
public void PickUp(){

}
public (?) getPosition(){ // should return robot's position

}
}

Class Area:

private int numberOfObjects;
private Robot robot;
private static final int X = 10;
private static final int Y = 10;
private Object [][] area; // grid

public Area(){ // defines a grid and robot
    area = new Area[X][Y];
    for(int a=0;a<X;a++){
        for(int b=0;b<Y;b++)
            area[a][b]=".";
    }

    numberOfObjects = 0; // grid is initially empty
    Area ar = new Area();
    robot = new Robot(ar);
}

public void Put(int x,int y){ // put the object to position (x,y)
    area[x][y]=numberOfObjects++;
}

public void PickUp(int x,int y){ // pick up the object in position (x,y)
    if(area[x][y]!=null){
        area[x][y]=numberOfObjects--;
    }
}

public void PrintAGrid(){
    for(int r=0;r<X;r++){
        for(int c=0;c<Y;c++)
        System.out.print(area[r][c]+" ");
     System.out.println();
    }
    System.out.println();
}
}

How can I put the robot in position (10,1)? How can I declare and set its orientation (i.e. on the right)? I guess it will be easy to write other methods, so I do not focus on it.

回答1:

There are several issues with your code.

Why do you have an instance of Robot inside the class Robot? You have not used that instance at all!
private Object [][] area; should be int[][] area. You always save int in this, right?
If I understand your requirements correctly, Your implementation of pick and put is not correct.

Here is a help how you can solve the problems. I had to think several times if Robot should be in Grid or it should be the other way. I ended up with Grid in Robot. May be Grid could be a singleton.

Here is our Grid

public class Grid {
    private int[][] numberOfObjects = new int[10][10];

    public void put(int x, int y) {
        numberOfObjects[y][x]++;
    }

    public void pick(int x, int y) {
        numberOfObjects[y][x]--;
    }
}

You can replace parameters int x, int y with a Point.

And here is the robot

public class Robot {
    private static final int NORTH = 0, EAST = 1, SOUTH = 2, WEST = 3;
    private int direction;
    private int x, y;

    private Grid grid;

    public Robot(Grid grid) {
        this.x = 0;
        this.y = 0;

        this.grid = grid;
        direction = NORTH;
    }

    public void right() {
        direction++;
        if (direction == 4) {
            direction = 0;
        }
    }

    public void left() {
        direction--;
        if (direction == -1) {
            direction = 3;
        }
    }

    public void forward() {
        if (direction == NORTH) {
            y--;
        } else if (direction == SOUTH) {
            y++;
        } else if (direction == EAST) {
            x++;
        } else if (direction == WEST) {
            x--;
        }
    }

    public void put() {
        grid.put(x, y);
    }

    public void pick() {
        grid.pick(x, y);
    }
}

回答2:

You need to represent the curent location with a variable and initialize it to the 10 1 postion, though your array goes 0-9 and 0-9 so this may be 9,0. to store this position maybe try a Point object that contains a Point x,y.

来源：https://stackoverflow.com/questions/16637006/position-and-orientation-of-robot-in-a-grid

标签

java

arrays

grid