CODEWITHSUNDEEP
androidkotlinandroid-recyclerview
user1801060
user1801060

Reputation: 2821

Recyclerview view not populating

I'm a Kotlin newbie learning how to create simple recyclerview apps. My code is supposed to list the integers 1..10 in vertically stacked cells. However, it only lists the first item. I've consulted several tutorials and reviewed my code several times(after long breaks), but I can't see anything wrong in my code.

I got the bright idea early today to print Log statements. Examining them, I note that my onBindViewHolder function is only called once. What blunder am I making?

Here is my log output:

D/QuoteAdapter: value is: 1
D/QuoteAdapter: index is: 0
D/QuoteAdapter: Size is: 10

my activity:

class MainActivity : AppCompatActivity() {
    lateinit var mRecyclerView: RecyclerView

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

        mRecyclerView = findViewById(R.id.recyclerView)
        mRecyclerView.layoutManager = LinearLayoutManager(this)

        mRecyclerView.adapter = QuoteAdapter()
        //mRecyclerView.setHasFixedSize(true)
    }
}

my adapter:

class QuoteAdapter : RecyclerView.Adapter<QuoteViewHolder>() {
    private val listOfInts = intArrayOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
    private val TAG = "QuoteAdapter"

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): QuoteViewHolder {
        val view = LayoutInflater.from(parent.context)
                .inflate(R.layout.recyclerview_item_row, parent, false)
        return QuoteViewHolder(view)
    }

    override fun getItemCount(): Int {
        Log.d(TAG, "Size is: ${listOfInts.size.toString()}")
        return listOfInts.size
    }

    override fun onBindViewHolder(holder: QuoteViewHolder, position: Int) {
        val item = listOfInts[position]
        Log.d(TAG, "value is: ${item.toString()}")
        Log.d(TAG, "index is: ${position.toString()}")
        holder.listTitle.text = item.toString()
    }
}

my viewholder:

class QuoteViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    val listTitle = itemView.findViewById(R.id.itemString) as TextView
}

my layout:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/itemString"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

my main layout is shown below:

<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="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

Upvotes: 3

Views: 220

Answers (3)

cactustictacs
cactustictacs

Reputation: 19612

Like Zain says, you can just use a TextView on its own in a layout file, which will also fix the problem (so long as its height is wrap_content!)

There are actually a few included with Android - type android.R.layout. and you'll see a few things, like simple_list_item_1 which is just a styled TextView (you can ctrl+click the reference or whatever to look at the file). Can be nice if you just want to make a quick thing!

The ID of the TextView in android.R.layout.simple_list_item_1 is @android:id/text1 - note the android prefix, because its part of the android resources, not your app's. Which means you have to reference the ID in the same way as the layout, with android at the front: android.R.id.text1

Upvotes: 3

Zain
Zain

Reputation: 40888

You can get rid of the LinearLayout in the list item layout, and only keep the TextView.

So, replace your list item layout with:

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/itemString"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

Upvotes: 2

David Kroukamp
David Kroukamp

Reputation: 36423

In your "my layout" try this:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/itemString"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

Notice layout_height of LinearLayout has changed to wrap_content

Also doubt you need the android:orientation="vertical" on your ViewHolders item xml unless you will add more than just 1 TextView in the future.

Upvotes: 4

Related Questions