how to disable back button in android

@Override
public void onBackPressed() {
    // do nothing.
}

Did you try onBackPressed() ?

@Override
public void onBackPressed() {
       // Do as you please
}

 @Override
 public void onBackPressed() {

    //super.onBackPressed();
    if(SOME_CONDITION_TO_CHECK){
        //THIS BLOCK WILL NOT DO ANYTHING AND WOULD DISABLE BACK BUTTON             
    }else{
       super.onBackPressed();
       //THIS BLOCK WILL BE CALLED IF ABOVE COND IS FALSE, AND WOULD ENABLE BACK BUTTON
    }   

 }