Android位图有时返回null

Question

I am making a brick-breaker game for android and attempting to change the image of the background. On the first run of the game this works 100% of the time.

     mBackgroundImage = BitmapFactory.decodeResource
                (gameView.getContext().getResources(), 
                R.drawable.planet3);

planet3 is in the res/drawable folder.

If i return to the previous screen and start a new game, I get a NPE roughly 90% of the time. if I use a resource that was provided with the framework i am working on which is in the same folder as "planet3", Strangely it works 100% of the time regardless of whether its a new game or the first game etc.

Why could this be happening some of the time and not others. I generally find that when it does work it is because i am debugging it and stepping through line by line, however this could just be coincidence.

The code i have at the moment is as follows, TheGame is the current Thread the game is running on, the code i pasted above is in the constructor of this, IE everytime a new game is made, the background should be set. you can also see the file structure on the left to verify that the file "background" is in the same folder as the "planet3":

as far as the error is concerned i don't have an actual error message as it just says that MOOC has stopped working, and then restarts the program.

Answer 1

如果您使用沉重的图像，可能会发生这种情况，或者请在此处发布所有代码以及异常，以获取更好的分辨率

Answer 2

I think that the reason for NPE in your case is :

The BitmapFactory is unable to find the context parameter gameView.getContext()

You should use :

mBackgroundImage = BitmapFactory.decodeResource
                (getApplicationContext().getResources(), 
                R.drawable.planet3);

If you have saved context in member variable ie mContext through constructor then you can use that :

mBackgroundImage = BitmapFactory.decodeResource
                (mContext.getResources(), 
                R.drawable.planet3);