Question

我正在尝试制作RPG游戏，而现在，我正在尝试从文本文件中加载地图。我复制并粘贴了第二层和第三层的第一层代码，但它只适用于第一层。当它尝试在第二层中创建一个新的BasicTile时，我得到一个null异常错误。根据错误，arrayId和imageId为null，但我无法理解为什么。请帮忙，谢谢!!!

//MapLoader Function
public void load(String path){
    mapLayer1 = new Tile[tilesWidth + 1][tilesHeight + 1];
    mapLayer2 = new Tile[tilesWidth + 1][tilesHeight + 1];
    mapLayer3 = new Tile[tilesWidth + 1][tilesHeight + 1];

    try{

        InputStream in = getClass().getResourceAsStream(path);
        BufferedReader br = new BufferedReader(new InputStreamReader(in));

        String line;
        int y = 0;

        while((line = br.readLine()) != null){ //Tile Layer 1
            if(line.equalsIgnoreCase("[LAYERTWO]")) break;
            String[] val = line.split(" ");

            for(int x = 0; x < tilesWidth; x++){
                String[] value = val[x].split(",");
                int arrayId = Integer.parseInt(value[0]);
                int imageId = Integer.parseInt(value[1]);
                if(arrayId == 0 && imageId == 4){ //Water
                    Tile tile = new AnimatedTile(x, y, arrayId, imageId, new int[] {0,1,2,1}, 750);
                    tilesLayer1.add(tile);
                    mapLayer1[x][y] = tile;
                }else{
                    Tile tile = new BasicTile(x, y, arrayId, imageId);
                    tilesLayer1.add(tile);
                    mapLayer1[x][y] = tile;
                }
            }
            y++;
        }

        y = 0;

        while((line = br.readLine()) != null){ //Tile Layer 2
            if(line.equalsIgnoreCase("[LAYERTHREE]")) break;
            String[] val = line.split(" ");

            for(int x = 0; x < tilesWidth; x++){
                String[] value = val[x].split(",");
                int arrayId = Integer.parseInt(value[0]);
                int imageId = Integer.parseInt(value[1]);
                if(arrayId == 0 && imageId == 4){ //Water
                    Tile tile = new AnimatedTile(x, y, arrayId, imageId, new int[] {0,1,2,1}, 750);
                    tilesLayer2.add(tile);
                    mapLayer2[x][y] = tile;
                }else{
                    Tile tile = new BasicTile(x, y, arrayId, imageId);
                    tilesLayer2.add(tile);
                    mapLayer2[x][y] = tile;
                }
            }
            y++;
        }

        y = 0;

        while((line = br.readLine()) != null){ //Tile Layer 3
            if(line.equalsIgnoreCase("[COLLIDERS]")) break;
            String[] val = line.split(" ");

            for(int x = 0; x < tilesWidth; x++){
                String[] value = val[x].split(",");
                int arrayId = Integer.parseInt(value[0]);
                int imageId = Integer.parseInt(value[1]);
                if(arrayId == 0 && imageId == 4){ //Water
                    Tile tile = new AnimatedTile(x, y, arrayId, imageId, new int[] {0,1,2,1}, 750);
                    tilesLayer3.add(tile);
                    mapLayer3[x][y] = tile;
                }else{
                    Tile tile = new BasicTile(x, y, arrayId, imageId);
                    tilesLayer3.add(tile);
                    mapLayer3[x][y] = tile;
                }
            }
            y++;
        }

        while((line = br.readLine()) != null){ //Colliders
            String[] val = line.split(" ");

            colliders.add(new Rectangle(Integer.parseInt(val[0]), Integer.parseInt(val[1]), Integer.parseInt(val[2]), Integer.parseInt(val[3])));
        }

        in.close();

    }catch(IOException e){
        e.printStackTrace();
    }
}

然后这是BaseTile类。

//BasicTile Class
public class BasicTile extends Tile{

    public BasicTile(int tileX, int tileY, int arrayId, int imageId) {
        super(tileX, tileY, arrayId, imageId);
    }

    public void update() {}

    public void render() {
        Handler.g.drawImage(image, tileX * Tile.WIDTH, tileY * Tile.HEIGHT, tileWidth * Tile.WIDTH, tileHeight * Tile.HEIGHT, null);
    }

}

这就是BasicTile从Tile Class继承的。

public abstract class Tile {

    public static final int WIDTH = 32;
    public static final int HEIGHT = 32;

    protected int tileX;
    protected int tileY;
    protected int tileWidth;
    protected int tileHeight;
    protected int arrayId;
    protected int imageId;
    protected BufferedImage image;

    public Tile(int tileX, int tileY, int arrayId, int imageId){
        this.tileX = tileX;
        this.tileY = tileY;
        this.arrayId = arrayId;
        this.imageId = imageId;

        switch(arrayId){
        case 0: 
            this.image = ImageHandler.getTileImage(imageId); 
            this.tileWidth = this.image.getWidth() / Tile.WIDTH; //This is where the error came up in the console.
            this.tileHeight = this.image.getHeight() / Tile.HEIGHT; 
            break;
        }
    }

    public abstract void update();

    public abstract void render();

}

再次感谢您的帮助。我知道这很多东西要看，但我不知道你们所需要的是什么。我评论了Tile Class中的错误，如果有帮助的话。

Answer 1

当调用Integer.parseInt并返回null时，这意味着该字符串的长度为0。在将它们传递给parseInt方法之前，我会检查数组的元素。

仅供参考，这是docs的相关部分：

第一个参数为null或是一个长度为零的字符串。

Java表示当他们刚刚工作时整数是空的

1 个答案: