[android] How to set radio button checked as default in radiogroup?

I have created RadioGroup and RadioButton dynamically as following:

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);

Here step radioBtn2.setChecked(true); causes radioBtn2 always checked. That means I cannot uncheck radioBtn2 by checking other two radio buttons (radioBtn1,radioBtn3). I want to make that RadioGroup can check only one radio button at a time (Now it can check two radiobutton at a time).

How can I solve this problem?

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");

radioGroup.addView(radioBtn1);
radioGroup.addView(radioBtn2);
radioGroup.addView(radioBtn3);
radioBtn2.setChecked(true);

There was same problem in my Colleague's code. This sounds as your Radio Group is not properly set with your Radio Buttons. This is the reason you can multi-select the radio buttons. I tried many things, finally i did a trick which is wrong actually, but works fine.

for ( int i = 0 ; i < myCount ; i++ )
{
    if ( i != k )
    {
        System.out.println ( "i = " + i );
        radio1[i].setChecked(false);
    }
}

Here I set one for loop, which checks for the available radio buttons and de-selects every one except the new clicked one. try it.

In the XML file set the android:checkedButton field in your RadioGroup, with the id of your default RadioButton:

<RadioGroup
    ....
    android:checkedButton="@+id/button_1">

    <RadioButton
        android:id="@+id/button_1"
        ...../>

    <RadioButton
        android:id="@+id/button_2"
        ...../>

    <RadioButton
        android:id="@+id/button_3"
        ...../>
</RadioGroup>

    RadioGroup radioGroup = new RadioGroup(WvActivity.this);
    RadioButton radioBtn1 = new RadioButton(this);
    RadioButton radioBtn2 = new RadioButton(this);
    RadioButton radioBtn3 = new RadioButton(this);

    radioBtn1.setText("Less");
    radioBtn2.setText("Normal");
    radioBtn3.setText("More");


    radioGroup.addView(radioBtn1);
    radioGroup.addView(radioBtn2);
    radioGroup.addView(radioBtn3);

    radioGroup.check(radioBtn2.getId());

In case for xml attribute its android:checkedButton which takes the id of the RadioButton to be checked.

<RadioGroup
...
...
android:checkedButton="@+id/IdOfTheRadioButtonInsideThatTobeChecked"
... >....</RadioGroup>

Add android:checked = "true" in your activity.xml

It's a bug of RadioGroup

RadioButton radioBtn2 = new RadioButton(context);

radioBtn2 without viewId, and generateViewId is in onChildViewAdded()

public void onChildViewAdded(View parent, View child) {
    if (parent == RadioGroup.this && child instanceof RadioButton) {
        int id = child.getId();
        // generates an id if it's missing
        if (id == View.NO_ID) {
            id = View.generateViewId();
            child.setId(id);
        }
        ((RadioButton) child).setOnCheckedChangeWidgetListener(
                mChildOnCheckedChangeListener);
    }

    if (mOnHierarchyChangeListener != null) {
        mOnHierarchyChangeListener.onChildViewAdded(parent, child);
    }
}

so, first radioGroup.addView(radioBtn2), then radioBtn2.setChecked(true);

Like this:

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");

radioGroup.addView(radioBtn1);
radioGroup.addView(radioBtn2);
radioGroup.addView(radioBtn3);

radioBtn2.setChecked(true);