OpenGL,Android注意事項初始化順序 NullPointer，androidnullpointer

OpenGL,Android注意事項初始化順序 NullPointer，androidnullpointer

BUG:

Caused by: java.lang.IllegalStateException: setRenderer has already been called for this instance.

或者NullPointer錯誤

解決方案：

把setEGLContextClientVersion(2);挪到setRenderer()前面。方法的注釋上寫到“If this method is called, it must be called beforesetRenderer(Renderer) is called. 
”。

拓展：

並且setRender（）之後之前的方法調用順序，也是固定。詳情可以看代碼注釋，如下：

This method should be called once and only once in the life-cycle of a GLSurfaceView.

（這些方法只能在CLSurfaceView中有且只能調用一次）

The following GLSurfaceView methods can only be called before setRenderer is called:

（setRender前調用，當然也包括setEGLContextClientVersion(2)）

• setEGLConfigChooser(boolean)
• setEGLConfigChooser(EGLConfigChooser)
• setEGLConfigChooser(int, int, int, int, int, int)

The following GLSurfaceView methods can only be called after setRenderer is called:

（setRender後調用）

• getRenderMode()
• onPause()
• onResume()
• queueEvent(Runnable)
• requestRender()
• setRenderMode(int)