focus on second edittext only if first is non-empty android

Question

Currently I have two edit-text,suppose I want to make validation for empty edittext check.What is better way for runtime validation.

My code is;

Answer 1

    final EditText ev1 = (EditText) findViewById(R.id.editText1);
    final EditText ev2 = (EditText) findViewById(R.id.editText2);

    ev1.setOnFocusChangeListener(new OnFocusChangeListener() {      
        @Override
        public void onFocusChange(View rv, boolean hasFocus) {
            if(!hasFocus && ev1.getText().length()==0)
            {    
                  new Handler().postDelayed(new Runnable() {

                  @Override
                  public void run() {
                       ev2.clearFocus();
                   ev1.requestFocus();

                  }
            }, 100);

         }
      }
    });