title: Uncheck all RadioButton in a RadioButtonGroup
body: <p>What I wanted to achieve is this: Right after the activity starts, I want that no RadioButton is selected/checked. </p>
  
  <p>My problem is this: When the activity starts, the first RadioButton is always selected/checked.</p>
  
  <p>I tried <code>radioButton1.setChecked(false)</code> right after initialization of the radiobutton(inside onCreate), but when the activity starts, I can't manually check/select the first radiobutton. Till I select the 2nd or 3rd radio button, I can now select/check the first radio button.</p>