Android Learning Note: Never Set 2 Different Layout To 1 Activity

This is the original post of mine, which is wrong in fact.

Just add the following codes behind "super.onCreate(savedInstanceState);" sentence in the onCreate(Bundle savedInstanceState) methed of the main Activity.

//Entering Splash Screen. Here I use the layout file welcome.xml

setContentView(R.layout.welcome);

// Creating a Handler object and operate it like this. You may set another waiting time

new Handler() {
    @Override    public void handleMessage(Message msg) {
        setContentView(R.layout.activity_main);
    }
}.sendEmptyMessageDelayed(1,2000);

After short enjoyness, I got into trouble caused by the codes below. Crap say no more, I used the methed setContentView() twice in the codes below, which caused serious NullPointerException in the following codes.

Maybe this is a stupid mistake for many of you, I thgink it valuable for me, for I have debuged the program and resulted others to make sense of it. And I'm impressed on this error, believing that I'll never make this kind of mistake.

Never Set 2 Different Layout To 1 Activity.