How to get checked button position in Android MaterialButtonToggleGroup

Issue

I have defined an MaterialButtonToggleGroup with 2 MaterialButton in my xml, in this way:

<com.google.android.material.button.MaterialButtonToggleGroup
    ...
    app:checkedButton="@+id/favorite_color1"
    app:singleSelection="true">

    <com.google.android.material.button.MaterialButton
        android:id="@+id/favorite_color1"
        ... />

    <com.google.android.material.button.MaterialButton
        android:id="@+id/favorite_color2"
        ... />

</com.google.android.material.button.MaterialButtonToggleGroup>

I found getCheckedButtonIds() method (that returns a List of Ids) and OnButtonCheckedListener (that returns an Integer Id), but the get(int index) method returns the View at the index position, not the View with a certain id.

How Can I get (programmatically) the View of the checked button in a given moment? There is a method returns the current checked position (or index)?

Solution

Since you are using app:singleSelection="true" you can use thegetCheckedButtonId() method to get the unique id of the selected MaterialButton in this group.
You can use something like:

MaterialButtonToggleGroup materialButtonToggleGroup = 
         findViewById(R.id.toggle_button_group);
int buttonId = materialButtonToggleGroup.getCheckedButtonId();
MaterialButton button = materialButtonToggleGroup.findViewById(buttonId);

You can also use getCheckedButtonIds() and cycle over the ids.

List<Integer> ids = materialButtonToggleGroup.getCheckedButtonIds();
for (Integer id:ids){
      MaterialButton materialButton = materialButtonToggleGroup.findViewById(id);
      //....
}

Answered By - Gabriele Mariotti