GeofireListAdapter

README.md

This is a ListAdapter for Android Lists that can show results from a Geofire query. It must be extended as shown in usage.java.

FirebaseListAdapter.java

import android.app.Activity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;

import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.Query;

import java.util.ArrayList;
import java.util.List;

/**
 * @author greg
 * @since 6/21/13
 *
 * This class is a generic way of backing an Android ListView with a Firebase location.
 * It handles all of the child events at the given Firebase location. It marshals received data into the given
 * class type. Extend this class and provide an implementation of <code>populateView</code>, which will be given an
 * instance of your list item mLayout and an instance your class that holds your data. Simply populate the view however
 * you like and this class will handle updating the list as the data changes.
 *
 * @param <T> The class type to use as a model for the data contained in the children of the given Firebase location
 */
public abstract class FirebaseListAdapter<T> extends BaseAdapter {

    protected Query mRef;
    protected Class<T> mModelClass;
    protected int mLayout;
    protected LayoutInflater mInflater;
    protected List<T> mModels;
    protected List<String> mKeys;
    protected ChildEventListener mListener;
    protected String ownKey = "";

    public FirebaseListAdapter() {
    }

    /**
     * @param mRef        The Firebase location to watch for data changes. Can also be a slice of a location, using some
     *                    combination of <code>limit()</code>, <code>startAt()</code>, and <code>endAt()</code>,
     * @param mModelClass Firebase will marshall the data at a location into an instance of a class that you provide
     * @param mLayout     This is the mLayout used to represent a single list item. You will be responsible for populating an
     *                    instance of the corresponding view with the data from an instance of mModelClass.
     * @param activity    The activity containing the ListView
     */
    public FirebaseListAdapter(Query mRef, Class<T> mModelClass, int mLayout, Activity activity) {
        this.mRef = mRef;
        this.mModelClass = mModelClass;
        this.mLayout = mLayout;
        mInflater = activity.getLayoutInflater();
        mModels = new ArrayList<T>();
        mKeys = new ArrayList<String>();
        // Look for all child events. We will then map them to our own internal ArrayList, which backs ListView
        mListener = this.mRef.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String previousChildName) {

                T model = dataSnapshot.getValue(FirebaseListAdapter.this.mModelClass);
                String key = dataSnapshot.getKey();

                if (ownKey.equals(key)) {
                    return;
                }

                // Insert into the correct location, based on previousChildName
                if (previousChildName == null) {
                    mModels.add(0, model);
                    mKeys.add(0, key);
                } else {
                    int previousIndex = mKeys.indexOf(previousChildName);
                    int nextIndex = previousIndex + 1;
                    if (nextIndex == mModels.size()) {
                        mModels.add(model);
                        mKeys.add(key);
                    } else {
                        mModels.add(nextIndex, model);
                        mKeys.add(nextIndex, key);
                    }
                }

                notifyDataSetChanged();
            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {
                // One of the mModels changed. Replace it in our list and name mapping
                String key = dataSnapshot.getKey();

                if (ownKey.equals(key)) {
                    return;
                }

                T newModel = dataSnapshot.getValue(FirebaseListAdapter.this.mModelClass);
                int index = mKeys.indexOf(key);

                mModels.set(index, newModel);

                notifyDataSetChanged();
            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {

                // A model was removed from the list. Remove it from our list and the name mapping
                String key = dataSnapshot.getKey();

                if (ownKey.equals(key)) {
                    return;
                }

                int index = mKeys.indexOf(key);

                mKeys.remove(index);
                mModels.remove(index);

                notifyDataSetChanged();
            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String previousChildName) {

                // A model changed position in the list. Update our list accordingly
                String key = dataSnapshot.getKey();

                if (ownKey.equals(key)) {
                    return;
                }
                T newModel = dataSnapshot.getValue(FirebaseListAdapter.this.mModelClass);
                int index = mKeys.indexOf(key);
                mModels.remove(index);
                mKeys.remove(index);
                if (previousChildName == null) {
                    mModels.add(0, newModel);
                    mKeys.add(0, key);
                } else {
                    int previousIndex = mKeys.indexOf(previousChildName);
                    int nextIndex = previousIndex + 1;
                    if (nextIndex == mModels.size()) {
                        mModels.add(newModel);
                        mKeys.add(key);
                    } else {
                        mModels.add(nextIndex, newModel);
                        mKeys.add(nextIndex, key);
                    }
                }
                notifyDataSetChanged();
            }

            @Override
            public void onCancelled(DatabaseError firebaseError) {}

        });
    }

    public void cleanup() {
        // We're being destroyed, let go of our mListener and forget about all of the mModels
        mRef.removeEventListener(mListener);
        mModels.clear();
        mKeys.clear();
    }

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

    @Override
    public Object getItem(int i) {
        return mModels.get(i);
    }

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

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        if (view == null) {
            view = mInflater.inflate(mLayout, viewGroup, false);
        }

        T model = mModels.get(i);
        // Call out to subclass to marshall this model into the provided view
        populateView(view, model);
        return view;
    }

    public void setOwnKey(String key) {
        ownKey = key;
    }

    /**
     * Each time the data at the given Firebase location changes, this method will be called for each item that needs
     * to be displayed. The arguments correspond to the mLayout and mModelClass given to the constructor of this class.
     * <p/>
     * Your implementation should populate the view using the data contained in the model.
     *
     * @param v     The view to populate
     * @param model The object containing the data used to populate the view
     */
    protected abstract void populateView(View v, T model);
}

GeofireListAdapter.java

import android.app.Activity;

import com.firebase.geofire.GeoLocation;
import com.firebase.geofire.GeoQuery;
import com.firebase.geofire.GeoQueryEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;
import com.google.firebase.database.ValueEventListener;

import java.util.ArrayList;
import java.util.HashMap;

/**
 * Created by jonah on 10/22/16.
 */

public abstract class GeofireListAdapter<T> extends FirebaseListAdapter<T> {

    protected DatabaseReference mRef;
    protected GeoQuery geoQuery = null;
    protected GeoQueryEventListener geoQueryEventListener = null;
    protected HashMap<String, DatabaseReference> pathReferences = new HashMap<String, DatabaseReference>();
    protected HashMap<String, ValueEventListener> pathListeners = new HashMap<String, ValueEventListener>();


    /**
     * @param mRef        The Firebase location to watch for data changes. Can also be a slice of a location, using some
     *                    combination of <code>limit()</code>, <code>startAt()</code>, and <code>endAt()</code>,
     * @param mModelClass Firebase will marshall the data at a location into an instance of a class that you provide
     * @param mLayout     This is the mLayout used to represent a single list item. You will be responsible for populating an
     *                    instance of the corresponding view with the data from an instance of mModelClass.
     * @param activity    The activity containing the ListView
     */
    public GeofireListAdapter(final DatabaseReference mRef,  Class<T> mModelClass, int mLayout, Activity activity) {
        this.mRef = mRef;
        this.mModelClass = mModelClass;
        this.mLayout = mLayout;
        mInflater = activity.getLayoutInflater();
        mModels = new ArrayList<T>();
        mKeys = new ArrayList<String>();
    }

    public void setGeoQuery(GeoQuery geoQuery) {
        final DatabaseReference mRef = this.mRef;
        if (geoQuery != null) {
            geoQuery.removeAllListeners();
        }
        this.geoQuery = geoQuery;
        this.geoQueryEventListener = new GeoQueryEventListener() {
            @Override
            public void onKeyEntered(String key, GeoLocation location) {
                if (ownKey.equals(key)) {
                    return;
                }
                DatabaseReference ref = mRef.child("contact/" + key);
                ValueEventListener listener = new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        T model = dataSnapshot.getValue(GeofireListAdapter.this.mModelClass);
                        if (model == null) {
                            return;
                        }

                        String key = dataSnapshot.getKey();

                        int index = mKeys.indexOf(key);

                        if (index == -1) {
                            mModels.add(model);
                            mKeys.add(key);
                        } else {
                            mModels.set(index, model);
                        }

                        notifyDataSetChanged();
                    }

                    @Override
                    public void onCancelled(DatabaseError databaseError) {}
                };
                pathReferences.put(key, ref);
                pathListeners.put(key, listener);
                ref.addValueEventListener(listener);
            }

            @Override
            public void onKeyExited(String key) {
                int index = mKeys.indexOf(key);
                if (index == -1) {
                    return;
                }
                mModels.remove(index);
                mKeys.remove(index);
                pathReferences.get(key).removeEventListener(pathListeners.get(key));
                pathReferences.remove(key);
                pathListeners.remove(key);

                notifyDataSetChanged();
            }

            @Override
            public void onKeyMoved(String key, GeoLocation location) {}

            @Override
            public void onGeoQueryReady() {}

            @Override
            public void onGeoQueryError(DatabaseError error) {}
        };

        geoQuery.addGeoQueryEventListener(geoQueryEventListener);
    }
}

usage.java

import android.app.Activity;
import android.graphics.Color;
import android.view.View;
import android.widget.TextView;

import com.firebase.geofire.GeoQuery;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.Query;

/**
 * @author greg
 * @since 6/21/13
 *
 * This class is an example of how to use FirebaseListAdapter. It uses the <code>Chat</code> class to encapsulate the
 * data for each individual chat message
 */
public class MyListAdapter extends GeofireListAdapter<Item> {

    public MyListAdapter(DatabaseReference ref, Activity activity, int layout) {
        super(ref, Item.class, layout, activity);
    }
  
    @Override
    protected void populateView(View view, Item item) {
        // add data to view
    }
}