I was trying simple customApp using RecyclerView. But error that layout_constraintEnd_toEndOf of button is not applied occurred. I expected result is the following image(right result). But real result is the following image(real result). For real result to be right result, What do I have to do? code :

<?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:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@ id/constraintRoot"
    android:descendantFocusability="blocksDescendants">

    <ImageView
        android:id="@ id/imageView"
        android:layout_width="100dp"
        android:layout_height="100dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent" />

    <TextView
        android:id="@ id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="40dp"
        android:text="TextView"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toEndOf="@ id/imageView"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@ id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginRight="20dp"
        android:text="Button"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

activity_main.xml

<?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@ id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

CustomAdapter.xml

class CustomViewHolder(view : View) : RecyclerView.ViewHolder(view){
    val image : ImageView = view.findViewById(R.id.imageView)
    val text : TextView = view.findViewById(R.id.textView)
    val button : Button = view.findViewById(R.id.button)
    init{
        view.setOnClickListener {
            Log.d("himaru", "${adapterPosition}")
        }
    }
}
class Data(val imageInt : Int, val name : String)
class CustomAdapter(val context : Context, val dataList : ArrayList<Data>) : RecyclerView.Adapter<CustomViewHolder>(){
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CustomViewHolder {
        val layout = LayoutInflater.from(parent.context).inflate(R.layout.list_activity, null)
        return CustomViewHolder(layout)
    }

    override fun onBindViewHolder(holder: CustomViewHolder, position: Int) {
        val data = dataList[position]
        holder.image.setImageResource(data.imageInt)
        holder.text.text = data.name
        holder.button.text = data.name   "Button"
        holder.button.setOnClickListener{
            Toast.makeText(context, holder.button.text, Toast.LENGTH_SHORT).show()
        }
    }

    override fun getItemCount() = dataList.size

}

MainActivity.xml

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val arrayList = arrayListOf<Data>()
        arrayList.add(Data(R.drawable.yihyun1, "yihyun1"))
        arrayList.add(Data(R.drawable.yihyun2, "yihyun2"))
        arrayList.add(Data(R.drawable.yihyun3, "yihyun3"))
        arrayList.add(Data(R.drawable.yihyun4, "yihyun4"))
        arrayList.add(Data(R.drawable.yihyun5, "yihyun5"))

        val recyclerView = findViewById<RecyclerView>(R.id.recyclerView)
        recyclerView.layoutManager = LinearLayoutManager(this)
        val adapter = CustomAdapter(this, arrayList)
        recyclerView.adapter = adapter
    }
}

real result :

right result :

CodePudding user response：

val layout = LayoutInflater.from(parent.context).inflate(R.layout.list_activity, null)

You have two issues here:

The first one: you set the parent to null, and that could be the main reason that it uses the default WRAP_CONTENT instead of using the parent's RecyclerView's MATCH_PARENT

You need to pass the parent instead

The second one: You use the two-arg version of the inflate() which assumes the value of the attachToRoot variable to true in case R.layout.list_activity is not null.

But you need to set attachToRoot to false by using the three-arg version:

Applying that:

val layout = LayoutInflater.from(parent.context).inflate(R.layout.list_activity, parent, false)

CodePudding user response：

By default the layout params of a child view in a recycler view is WRAP_CONTENT, WRAP_CONTENT

Set the params after creating the view:

itemView.layoutParams = RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT)

or Java:

itemView.setLayoutParams(new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));