Android Material - 无法投射到 com.google.android.material.chip.ChipGroup

Question

I have a component_category_view.xml with a ChipGroup initialized inside a constraintLayout that has an id categoryList , I'm running the following CategoryView.kt class to inflate it and update it with chips dynamically and i have it placed inside my activity.

class CategoryView @JvmOverloads constructor(
context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : ConstraintLayout(context, attrs, defStyleAttr) {

init {
    inflateLayout()
}


private fun inflateLayout() {
    val inflater = context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
    inflater.inflate(R.layout.component_category_view, this, true)
}
fun updateCategories(categories: List<Category>){
    categories.forEach {
        var chipText = "${it.title.capitalize()} (${it.amount})"
        val chip = Chip(this@CategoryView.context)
        chip.text = chipText
        chip.isCheckable = true
        chip.chipBackgroundColor = null

        categoryList.addView(chip)
    }
}


}

When I run however and my code reaches the part where it's calling updateCategories with a list of Categories, the following error comes up:

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.company.project, PID: 8262 java.lang.ClassCastException: com.company.project.common.ui.CategoryView cannot be cast to com.google.android.material.chip.ChipGroup

the component_category_view.xml looks like this

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
                                               xmlns:app="http://schemas.android.com/apk/res-auto"
                                               android:orientation="vertical"
                                               android:layout_width="match_parent"
                                               android:layout_height="match_parent"
                                               android:background="@drawable/layout_border_bottom">

<com.google.android.material.chip.ChipGroup
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        android:id="@+id/categoryList"/>

</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

Use Material theme instead of appCompact to solve chip problem:

<style name="AppTheme" parent="Theme.MaterialComponents.Light.Bridge">

<item name="colorAccent">@color/colorAccent</item>

</style>

<style name="AppTheme.NoActionBar">

<item name="windowActionBar">false</item>

<item name="windowNoTitle">true</item>

</style>

Updated

The error occurred because you're adding chip to categoriesList but it's required a chip group like below example:

private fun createChip(name: String, index: Int){

val chip = Chip(chip_group.context)

chip.id = index

chip.text = name

chip.isClickable = true

chip.isCheckable = true

chip.isCheckedIconVisible = false

chip_group.addView(chip)

}

And

override fun onActivityCreated(savedInstanceState: Bundle?) {

 super.onActivityCreated(savedInstanceState)

  for ((index, item) in categories.withIndex()){
createChip(item.name, index)} }

Answer 2

In my case, the error was caused by the id field within the Chip view.

<com.google.android.material.chip.Chip
                android:id="@+id/chip_fragment_1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>

After changing the value of the id field, the error went away.