Null returned when using findViewById

Hello,
sometime you have nullpointerexception when using findViewById like the code snippet bellow
                TextView tv=(TextView)findViewById(R.id.textViewVV);
if(tv!=null)
tv.setText("Not Null");
this is done because you call different of the set layout
the solution is to call views from the layout you use on the current Activity
like this

setContentView(R.layout.test);

TextView tv=(TextView)findViewById(R.id.textViewVV);

if(tv!=null)

tv.setText("Good");

textViewVV is in test layout, so, this code works fine.