数组中Java的平铺地图

Question

I am attempting to iterate through a 2D array of integers to generate a tiled map using Java's Graphics2D.

    int[][] mapArray = {{1, 1, 1, 1, 1, 1, 1, 1},
                    {1, 0, 0, 0, 0, 0, 0, 1},
                    {1, 0, 0, 0, 0, 0, 0, 1},
                    {1, 0, 0, 0, 0, 0, 0, 1},
                    {1, 0, 0, 0, 0, 0, 0, 1},
                    {1, 1, 1, 1, 1, 1, 1, 1}};

    public void draw(Graphics2D g2d){
    for(int y = 0; y < mapArray.length; y++){
        for(int x = 0; x < mapArray[0].length; x++){
            if(mapArray[x][y] == 1){
                 ImageIcon ic = new ImageIcon("/Textures/stone.jpg");
                 g2d.drawImage(ic.getImage(), x, y, null);
            }
            else if(mapArray[x][y] == 0){
                 ImageIcon ic = new ImageIcon("/Textures/water.jpg");
                 g2d.drawImage(ic.getImage(), x, y, null);
            }

I just can't seem to wrap my head around the logic of iterating a 2D array. Ideally, each 0 would represent a water tile while each 1 would represent a stone tile. Every time I run this I get a NullPointerException .

Answer 1

x and y are wrong way around

public void draw(Graphics2D g2d){
    for(int y = 0; y < mapArray.length; y++){
        for(int x = 0; x < mapArray[y].length; x++){ //you want to use y here not 0
            if(mapArray[y][x] == 1){                 //first box is outer array second is inner one
                ImageIcon ic = new ImageIcon("/Textures/stone.jpg");
                g2d.drawImage(ic.getImage(), x, y, null);
            } else if(mapArray[y][x] == 0){
                ImageIcon ic = new ImageIcon("/Textures/water.jpg");
                g2d.drawImage(ic.getImage(), x, y, null);
            }
        }
    }
}

Answer 2

I could see potentially two big issues in your code, in your code "y" represents rows and "x" represents columns but in your if statement you are picking [column][row] and while having a dry run you are probabily counting [row][column] and secondly you are always counting columns that are present in first row. if your data structure is always nXn in such case it will work but in any other case you would have different results and you might encounter ArrayIndexOutofBound exception.