Retain & restore recycler view scroll position

StatefulRecyclerView.java

package eu.f3rog.ui.custom;

import android.content.Context;
import android.os.Bundle;
import android.os.Parcelable;
import android.support.annotation.Nullable;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;

/**
 * Class {@link StatefulRecyclerView} extends {@link RecyclerView} and adds position management on configuration changes.
 *
 * @author FrantisekGazo
 * @version 2016-03-15
 */
public final class StatefulRecyclerView
        extends RecyclerView {

    private static final String SAVED_SUPER_STATE = "super-state";
    private static final String SAVED_LAYOUT_MANAGER = "layout-manager-state";

    private Parcelable mLayoutManagerSavedState;

    public StatefulRecyclerView(Context context) {
        super(context);
    }

    public StatefulRecyclerView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public StatefulRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected Parcelable onSaveInstanceState() {
        Bundle bundle = new Bundle();
        bundle.putParcelable(SAVED_SUPER_STATE, super.onSaveInstanceState());
        bundle.putParcelable(SAVED_LAYOUT_MANAGER, this.getLayoutManager().onSaveInstanceState());
        return bundle;
    }

    @Override
    protected void onRestoreInstanceState(Parcelable state) {
        if (state instanceof Bundle) {
            Bundle bundle = (Bundle) state;
            mLayoutManagerSavedState = bundle.getParcelable(SAVED_LAYOUT_MANAGER);
            state = bundle.getParcelable(SAVED_SUPER_STATE);
        }
        super.onRestoreInstanceState(state);
    }

    /**
     * Restores scroll position after configuration change.
     * <p>
     * <b>NOTE:</b> Must be called after adapter has been set.
     */
    private void restorePosition() {
        if (mLayoutManagerSavedState != null) {
            this.getLayoutManager().onRestoreInstanceState(mLayoutManagerSavedState);
            mLayoutManagerSavedState = null;
        }
    }

    @Override
    public void setAdapter(Adapter adapter) {
        super.setAdapter(adapter);
        restorePosition();
    }
}

Hello ! It works perfectly, thanks a lot.
For people asking how to use it: import the file in your project, and just declare your StatefulRecyclerview in your layout files instead of the native "android.support.v7.widget.RecyclerView"

Error inflating class StatefulRecyclerView

Thanks for the code. It's Working!

Thanks a lot.
Working for me too, tested it on Android 6, 8 and 9 devices.

How to use this one? Please tell me an example

The usage is as @jrm-d wrote:

For people asking how to use it: import the file in your project, and just declare your StatefulRecyclerview in your layout files instead of the native "android.support.v7.widget.RecyclerView"

But I didn't use it in a long time (3 years old snippet)

Error inflating class StatefulRecyclerView

How to use this code?
Please explain a full person or send an example

Thank you for the code, this works inside fragment 👍 , but not working inside activity 👎
How to use this code?
Please explain a full person or send an example

Worked fine. Thanks

If you are looking for a solution, don't do like that, you will never know how to use the code.

Now do like this:
All below code you put in the activity (where you using the Recyclerview)

// save position:
RecyclerView rcv = findViewById(.....);
rcv.setAdapter(....);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
rcv.setLayoutManager(layoutManager);

rcv.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                pos = layoutManager.findFirstVisibleItemPosition();
               // everytime you scroll the list, new position will be saved in app's data storage:
                SharedPreferences preferences = getSharedPreferences("anyname", MODE_PRIVATE);
                SharedPreferences.Editor editor = preferences.edit();
                editor.putInt("KEY_LAST_POSITION", pos).apply();
            }
        });

// using position: 
SharedPreferences preferences = getSharedPreferences("anyname", MODE_PRIVATE);
int position = preferences.getInt("KEY_LAST_POSITION", 0); // 0 is the default value
rcv.scrollToPosition(position);

@chieuancucbo you don't know your code. It is remembering an item position, not the exact scroll.