androidandroid-xmlandroid-databindingandroid-binding-adaptermaterialbutton

Android MaterialButton Set Check in XML for DataBinding


I'm using MaterialButton within MaterialButtonToggleGroup:

<com.google.android.material.button.MaterialButtonToggleGroup
    android:id="@+id/majors_toggleGroup"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="8dp">

    <com.google.android.material.button.MaterialButton
        android:id="@+id/cs_button"
        style="@style/Widget.MaterialComponents.Button.OutlinedButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="true"                //doesn't work
        android:text="CS" />

    ...

The arrtribute android:checked just doesn't work, I can use setCheck() in Activity or Fragment, but for using DataBniding I have to use the XML attribute. Any help?


Solution

  • Finally, I have to use BindingAdapter function to achieve this functionality.

    1. Create BindingAdapter Function:

    object DataBindingUtil {
        @BindingAdapter("checkedIndexes")        //custom attribute
        @JvmStatic
        fun setChecked(toggleGroup: MaterialButtonToggleGroup, checkedIndexes: List<Int>) {
            checkedIndexes.forEach {
                (toggleGroup.getChildAt(it) as MaterialButton).isChecked = true
            }
        }
    }
    

    2. Apply to MaterialButtonToggleGroup:

    <com.google.android.material.button.MaterialButtonToggleGroup
        android:id="@+id/majors_toggleGroup"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        app:checkedIndexes="@{viewModel.majorIndexes}">    //here, multi-selection for now