BUG:

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

或者NullPointer错误

解决方法：

把setEGLContextClientVersion(2);挪到setRenderer()前面。方法的注释上写到“If this method is called, it must be called beforesetRenderer(Renderer) is called. 
”。

拓展：

并且setRender（）之后之前的方法调用顺序，也是固定。详情可以看代码注释，如下：

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

（这些方法只能在CLSurfaceView中有且只能调用一次）

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

（setRender前调用，当然也包括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后调用）

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

OpenGL,Android注意事项初始化顺序 NullPointer