您需要一个onCreate（）方法。

You need an onCreate() method.

  @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        AssetManager am = getAssets();//this should not get a nullpointerexception
  }

或执行以下操作：

在您的活动（哪一个调用图像加载器）这样写：

In your Activity (whichever one calls image loader) write this:

ImageLoader il = new ImageLoader(this);//this being the context.

然后在你的类ImageLoader的可以使用

Then in your ImageLoader class you can use

AssetManager am = context.getAssets();//context being the activity which called this class.