Java说他们刚刚工作的整数是空的

Question

我想做一个RPG游戏，现在，我试图从文本文件加载地图。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。当它试图在第二层中创建一个新的BasicTile时，我得到一个空的异常错误。根据错误，arrayId和imageId为空，但我不明白为什么。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继承的Tile类。

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。我知道这是很多东西要看，但我不知道你们都需要什么。我评论说我在Tile Class中遇到错误，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，我会检查数组中的元素。

仅供参考，这里是从docs的相关部分：

第一个参数是空值或零长度的字符串。