Android ViewHolder pattern memory leak

Question

I am using the below code for my getView() in BaseAdapter.

When I try to rotate the phone a few times, each time the heap memory is increasing. While I analyzed this in the memory analyser, I found that new TextView's are being created, but the old ones are not being destroyed.

What should I do to fix this?

Full Adapter code:

package in.mypack.ui;

import static in.mypack.Util.getHelper;
import in.mypack.data.MyClass;
import in.mypack.MyMap;

import java.util.ArrayList;
import java.util.Locale;
import java.util.Map.Entry;

import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Typeface;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Filter;
import android.widget.TextView;

public class MyAdapter extends BaseAdapter {

    private Filter filter;
    private MyMap<String, MyClass> items;
    private MyMap<String, MyClass> totalItems;
    private Locale locale;
    private LayoutInflater inflater;
    @SuppressWarnings("unused")
    private final String TAG = "MyAdapter";

    public MyAdapter(MyMap<String, MyClass> objects) {
        items = objects;
        inflater = getHelper().getLayoutInflater();
    }

    private static class ViewHolder {
        TextView one, two, three;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.list_item, null);
            holder = new ViewHolder();
            holder.one = (TextView) convertView.findViewById(R.id.one);
            holder.two = (TextView) convertView.findViewById(R.id.two);
            holder.three = (TextView) convertView.findViewById(R.id.three);
            Typeface font = Typeface.createFromAsset(getHelper().getAssets(), getHelper().getString(R.string.font_custom));
            holder.one.setTypeface(font);
            holder.two.setTypeface(font);
            holder.three.setTypeface(font);
            convertView.setTag(holder);
        }
        else {
            holder = (ViewHolder) convertView.getTag();
        }

        MyClass myObject = getItem(position);
        holder.one.setText(myObject.getName());
        holder.two.setText(myObject.getInfo());
        holder.three.setText(myObject.getSize());
        addColors(convertView, holder, myObject);
        return convertView;
    }

    private void addColors(View convertView, ViewHolder holder, MyClass myObject) {
        if (myObject.isValid()) {
            convertView.setBackgroundColor(Color.argb(255,225,225,225));
            holder.one.setPaintFlags(holder.one.getPaintFlags() & (~Paint.STRIKE_THRU_TEXT_FLAG));
            holder.two.setPaintFlags(holder.one.getPaintFlags() & (~Paint.STRIKE_THRU_TEXT_FLAG));
        }
        else {
            convertView.setBackgroundColor(Color.argb(255,185,185,185));
            holder.one.setPaintFlags(holder.one.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
            holder.two.setPaintFlags(holder.one.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
        }
    }

    public Filter getFilter() {
        if (filter == null) {
            locale = Locale.getDefault();
            filter = new Filter() {
                @Override
                protected FilterResults performFiltering(CharSequence query) {
                    FilterResults results = new FilterResults();
                    if (totalItems == null) {
                        totalItems = new MyMap<String, MyClass>();
                        totalItems.putAll(items);
                    }

                    if (query == null || 0 == query.length()) {
                        results.count = totalItems.size();
                        results.values = totalItems;
                    }
                    else {
                        MyMap<String, MyClass> filteredList = new MyMap<String, MyClass>();
                        MyMap<String, MyClass> containsList = new MyMap<String, MyClass>();
                        int size = totalItems.size();
                        for (int i = 0; i < size; i++) {
                            Entry<String, MyClass> entry = totalItems.getEntry(i);
                            if (entry.getValue().getTitle().toLowerCase(locale).startsWith(query.toString().toLowerCase(locale))) {
                                filteredList.putEntry(entry);
                            } else if (entry.getValue().getTitle().toLowerCase(locale).contains(query.toString().toLowerCase(locale))) {
                                containsList.putEntry(entry);
                            }
                        }
                        filteredList.putAll(containsList);
                        results.count = filteredList.size();
                        results.values = filteredList;
                    }
                    return results;
                }

                @SuppressWarnings("unchecked")
                @Override
                protected void publishResults(CharSequence query, FilterResults results) {
                    items.clear();
                    items.putAll((MyMap<String, MyClass>) results.values);
                    notifyDataSetChanged();
                }

            };
        }
        return filter;
    }

    public void filter(String query) {
        getFilter().filter(query);
    }

    @Override
    public int getCount() {
        return items.size();
    }

    @Override
    public MyClass getItem(int index) {
        return items.get(index);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    public void add(MyClass myObject) {
        items.sortOnPut(myObject.getName(), myObject, MyMap.Sorting.Value);
    }
}

Answer 1

I've experienced a problem in RecyclerViews leaking the View hierarchy of the Fragment, due to the RecyclerView not unregistering from the Adapter when the Fragment is destroyed.

Your memory leak may there, and have nothing to do with the ViewHolders.

As a quick solutions, you could unregister the RecyclerView from the Adapter in #onDestroyView():

@Override
public void onDestroyView() {
    super.onDestroyView();
    mRecyclerView.setAdapter(null);
}

Have a look at this, where you'll find the full explanation.

Answer 2

Whilst the TextViews are being retained in memory, that doesn't mean that it is your use of the View holder pattern which is the culprit.

In this case, I believe it is your Filter - you are creating an inner anonymous class which keeps a reference to the Adapter, which keeps a reference to the Inflater, which keeps reference to the Context that created it.

Filters (performFiltering) are run in a background thread, and will be keeping your activity alive longer than it wants to be.

Try moving the implementation of Filter into a separate class, or as a static inner class.

Answer 3

you should not use application context in your list adapter, Please use the activity context. if you are using in fragment and dont want to re create it the use Fragment's setRetainInstance(boolean) true, but dont use application context.

Answer 4

Have you tried to declare the TextView's in your ViewHolder separately instead of inlining them together?