2

我在最新游戏中设置图像时遇到问题。当我调用方法getImage(String)时，我得到这样的图像：

Image head = getImage("Torso_model_01.png");

我收到以下错误消息：

Err: java.lang.NullPointerException
  At PB2Main.Body(Body.java : 27)
  ...

等等...

在本教程中，它解释了如何使用 ImageIcon 获取图像，如下所示：

String imgFile = "Images/" + img;
URL imgURL = getClass().getClassLoader().getResource(imgFile);
ImageIcon imageIcon;
Image image;
 if(imgURL != null){
  imageIcon = new imageIcon(imgURL);
  image = imageIcon.getImage();
 }

 final Image anImage = image;

我为此做了一个方法：

public URL getURL(String img){
  String imgFile = "Images/" + img;
  URL imgURL = getClass().getClassLoader().getResource(imgFile);
  return imgURL;
}

然后我做了一个名为 getImage(String) 的方法

public Image getImage(String img) {
  ImageIcon imageIcon;
  Image image;
  URL imgURL = getClass().getClassLoader().getResource(getURL(img));
  if(imgURL != null){
   imageIcon = new ImageIcon(imgURL);
   image = imageIcon.getImage();
   return image;
  }
   System.err.println("Unable to Locate Image: " + imgURL);
}

现在，我有一个名为Body. 在那个类中，我有一个构造函数：

public Body(float x, float y, String head, String torso){//atm this is just so i can                    get the image to actually draw on the screen
Image Head = debugger.getImage(head);// debugger doubles as a library and debugger
//i also can't have this class extend debugger otherwise it will create a window :/
// is that a glitch or something in Java? :L perhaps i just don't understand
// inheritance very well and what happens exactly when you inherit a class :(
Image Torso = debugger.getImage(torso);

 g2.drawImage(Head, canvas.geWidth()/ 2,canvas.getHeight()/2, null)// canvas: the window to  
 //draw to
 // can someone also quickly explain in their answer what an image observer is please?
 g2.drawImage(Torso, Head.getX() - 5, Head.getY() - 5, null);
}

编译器给了我以下错误信息：

java.lang.NullPointerException
At PlazmaBurst2.Body(Body.java: 37)

//the code it brings me to is line 1 in the constructor:
/* null: */ Image Head = debugger.getImage(img);

我不明白这个 NullPointerException 是从哪里来的。我完全按照他们在同一站点的“自定义图形编程”部分中的操作方式进行了操作。

如果我只是复制和粘贴代码，代码就可以正常工作，但如果我使用 method 就不行getImage(String)。

4

1 回答 1

1

你的问题是在第 3 行getImage(String)：

URL imgURL = getClass().getClassLoader().getResource(getURL(img));

这应该改为：

URL imgURL = getURL(img);
于 2017-08-09T13:30:15.763 回答