title: How to set radio button checked as default in radiogroup?
body: <p>I have created  <code>RadioGroup</code> and <code>RadioButton</code> dynamically as following:</p>
  
  <pre><code>RadioGroup radioGroup = new RadioGroup(context);
                      RadioButton radioBtn1 = new RadioButton(context);
                      RadioButton radioBtn2 = new RadioButton(context);
                      RadioButton radioBtn3 = new RadioButton(context);
  
                      radioBtn1.setText("Less");
                      radioBtn2.setText("Normal");
                      radioBtn3.setText("More");
  
                      radioBtn2.setChecked(true);
  
                      radioGroup.addView(radioBtn1);
                      radioGroup.addView(radioBtn2);
                      radioGroup.addView(radioBtn3);
  </code></pre>
  
  <p>Here step <code>radioBtn2.setChecked(true);</code> causes <code>radioBtn2</code> always checked. That means I cannot uncheck <code>radioBtn2</code> by checking other two radio buttons (<code>radioBtn1</code>,<code>radioBtn3</code>). I want to make that <code>RadioGroup</code> can check only one radio button at a time (Now it can check two radiobutton at a time).</p>
  
  <p>How can I solve this problem?</p>