Ondraw() Method Work Only When I Creating My Object In The Ondraw()

I got a problem. I don't know why I can't create a object for example in my iniGame() method. When I create a object from the GameObject class and use the method render() in the on

Solution 1:

You are getting a NullPointerException because your initGame is probably not called. At least not on the Object where onDraw is called. What I mean is that there are two instances of your GameView. The first instance is the one you create manually using:

gameView = new GameView(this);

The second instance is created from the XML-File, since you are defining:

<de.fhflensburg.manichja.barrier51.GameView
    android:id="@+id/gameView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    />

So this second instance is created automatically by the App. And you don't know at the beginning, which of the three constructors is called. There are two things you should change:

1. In your activity, replace gameView = new GameView(this); with gameView = (GameView) findViewById(R.id.gameView);. This will give you the correct instance of your GameView. Please refer to the View-Doc for more details.
2. In your GameView class, add a call to initGame in all three constructors. This ensures that the elements are initialized, no matter what constructor is called.