Looks like your text view does not exist. try wrapping line 29 with an 'if' statement such as this:
if(tv1 != null){
//original line 29 goes here
}
and run it again. The exception shouldn't happen this time. If it indeed does not happen, I think your best bet would be to recheck the name of your text view, make sure it exits in the same layout xml you are sending to setContentView().