MainActivity RecyclerView lags

Question

My app, particularly the MainActivity suffers from some lag when I scroll through the RecyclerView. I tried to fix OverDraw as much as I can.

This is what my OverDraw screenshot looks like:

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:ads="http://schemas.android.com/apk/res-auto"
android:background="@drawable/background"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".ChordsList.ChordsListActivity">

<RelativeLayout
    android:id="@+id/layout_top"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/logo"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:scaleType="fitStart"
        android:src="@drawable/icon_verde_acqua_tras"/>

    <ImageButton
        android:id="@+id/menu"
        android:background="@color/trans"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:src="@drawable/tasto_menu"
        android:scaleType="fitCenter"
        android:layout_centerVertical="true"
        android:layout_alignParentEnd="true"
        android:layout_marginTop="20dp"
        android:onClick="showMenu"/>

    <ImageButton
        android:id="@+id/search"
        android:background="@color/trans"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:src="@drawable/tasto_ricerca"
        android:scaleType="fitCenter"
        android:layout_centerVertical="true"
        android:onClick="onSearchButtonPressed"
        android:layout_toStartOf="@id/menu"
        android:layout_marginTop="20dp" />

    <ImageButton
        android:id="@+id/tuner"
        android:background="@color/trans"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_centerVertical="true"
        android:onClick="onTunerButtonPressed"
        android:src="@drawable/tuner"
        android:scaleType="fitCenter"
        android:layout_toStartOf="@id/search"
        android:layout_marginTop="20dp" />



</RelativeLayout>

<android.support.v7.widget.RecyclerView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/chords_recycler"
    android:layout_below="@+id/layout_top"
    android:layout_alignParentStart="true"
    android:layout_marginTop="25dp" />
</RelativeLayout>

row.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="wrap_content">

<TextView
    android:id="@+id/nome"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAllCaps="true"
    android:layout_centerVertical="true"
    android:textSize="25sp"
    android:layout_marginTop="10dp"
    android:fontFamily="sans-serif-condensed"
    android:textStyle="bold"
    android:textColor="@color/black" />

<ImageView
    android:id="@+id/immagine_accordo"
    android:layout_width="130dp"
    android:layout_marginTop="5dp"
    android:layout_height="100dp"
    android:scaleType="fitCenter"
    android:layout_alignParentEnd="true"/>

</RelativeLayout>

Assuming that the problem is OverDraw (please tell me if it's not), how can I improve it further? I need everything that is in the Image, so I cannot remove the background.

As suggested by Ivanhoe, OverDraw does not seem to be a problem. The Adapter class and binding could be.

Adapter class:

public class ChordsListAdapter extends RecyclerView.Adapter<ChordsListAdapter.MyViewHolder> {
private ArrayList<Accordo> chordsList;
Context c;



public class MyViewHolder extends RecyclerView.ViewHolder {
    public TextView nome; //note
    public ImageView immagine;

    public MyViewHolder(View view) {
        super(view);
        nome = (TextView) view.findViewById(R.id.nome);
        immagine = (ImageView) view.findViewById(R.id.immagine_accordo);
    }
}

public ChordsListAdapter(Context c, ArrayList<Accordo> chordsList) {
    this.chordsList = chordsList;
    this.c = c;
}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.row, parent, false);

    return new MyViewHolder(itemView);
}

@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
    Accordo chord = chordsList.get(position);
    holder.nome.setText(chord.getName());
    holder.immagine.setImageResource(chord.getImage()[0]);
}

@Override
public int getItemCount() {
    return chordsList.size();
}
}

Answer 1

You're instantiating MyViewHolder for every binding, that means you're executing findViewById for each item which is an expensive method. A solution would be to cache the created instance of MyViewHolder in onCreateViewHolder by assigning it to the view tag, and reuse it. Have a look a this https://developer.android.com/training/improving-layouts/smooth-scrolling.html