RecyclerView drawing issue

Question

I'm starting new activity with RecyclerView from main activity. Items displaying correctly. But on scroll something strange happened. Items are not correctly rendered. Same RecyclerView works correctly if it's in main screen.

it's copy of code from here

Main activity:

public class MainActivity extends AppCompatActivity {

    ImageButton templatButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        templatButton = findViewById(R.id.template_button);
        templatButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Intent myIntent = new Intent(getBaseContext(), NewActivity.class);
                startActivity(myIntent);
            }
        });
    }

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">

    <ImageButton
        android:id="@+id/template_button"
        android:layout_width="180dp"
        android:layout_height="180dp"
        android:layout_marginStart="8dp"
        android:layout_marginBottom="28dp"
        android:background="@drawable/template_icon"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

</android.support.constraint.ConstraintLayout>

onCreate method in new activity:

    public class NewActivity extends AppCompatActivity {
        RecyclerView recyclerView;

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_list);

                // Initializing list view with the custom adapter
                ArrayList <Item> itemList = new ArrayList<Item>();

                ItemArrayAdapter itemArrayAdapter = new ItemArrayAdapter(R.layout.list_item, itemList);
                recyclerView = (RecyclerView) findViewById(R.id.item_list);
                recyclerView.setLayoutManager(new LinearLayoutManager(this));
                recyclerView.setItemAnimator(new DefaultItemAnimator());
                recyclerView.setAdapter(itemArrayAdapter);

                // Populating list items
                for(int i=0; i<100; i++) {
                    itemList.add(new Item("Item " + i));
                }

            }
}

item array adapter:

public class ItemArrayAdapter extends RecyclerView.Adapter<ItemArrayAdapter.ViewHolder> {

    //All methods in this adapter are required for a bare minimum recyclerview adapter
    private int listItemLayout;
    private ArrayList<Item> itemList;
    // Constructor of the class
    public ItemArrayAdapter(int layoutId, ArrayList<Item> itemList) {
        listItemLayout = layoutId;
        this.itemList = itemList;
    }

    // get the size of the list
    @Override
    public int getItemCount() {
        return itemList == null ? 0 : itemList.size();
    }


    // specify the row layout file and click for each row
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(listItemLayout, parent, false);
        ViewHolder myViewHolder = new ViewHolder(view);
        return myViewHolder;
    }

    // load data in each row element
    @Override
    public void onBindViewHolder(final ViewHolder holder, final int listPosition) {
        TextView item = holder.item;
        item.setText(itemList.get(listPosition).getName());
    }

    // Static inner class to initialize the views of rows
    static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        public TextView item;
        public ViewHolder(View itemView) {
            super(itemView);
            itemView.setOnClickListener(this);
            item = (TextView) itemView.findViewById(R.id.row_item);
        }
        @Override
        public void onClick(View view) {
            Log.d("onclick", "onClick " + getLayoutPosition() + " " + item.getText());
        }
    }
}

activitiy_list.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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.support.v7.widget.RecyclerView
        android:id="@+id/item_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scrollbars="vertical"
        />
</LinearLayout>

list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<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/row_item"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"/>
</LinearLayout>

Answer 1

1) Notify your adapter after

  recyclerView.setAdapter(itemArrayAdapter);

  itemArrayAdapter.notifyDataSetChanged();

also make sure your activity doesn't have any overlay layout , please do verify once again. 2) On your activity switch

 templatButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Intent myIntent = new Intent(getBaseContext(), NewActivity.class);
            startActivity(myIntent);
        }
    });

instead use

 templatButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Intent myIntent = new Intent(getApplicationContext(), NewActivity.class);
            startActivity(myIntent);
        }
    });

use getApplicationContext() you can get more in detail here

Answer 2

Set Adapter after Populating list items

Replace you NewActivity.java code with below code paste after this line setContentView(R.layout.activity_list);

        // Initializing list view with the custom adapter

            ArrayList <Item> itemList = new ArrayList<Item>();

            recyclerView = (RecyclerView) findViewById(R.id.item_list);
            recyclerView.setLayoutManager(new LinearLayoutManager(this));
            recyclerView.setItemAnimator(new DefaultItemAnimator());
            
            //Set Adapter Here
            ItemArrayAdapter itemArrayAdapter = new ItemArrayAdapter(R.layout.list_item, itemList);
            recyclerView.setAdapter(itemArrayAdapter);

            // Populating list items
            for(int i=0; i<100; i++) {
                itemList.add(new Item("Item " + i));
            }

Happy Coding!!!