Load more tracks when scrolling

Author: kaaes

app/src/main/java/com/spotify/sdk/android/MainActivity.java

@@ -32,6 +32,7 @@ public class MainActivity extends AppCompatActivity {
     private SpotifyService mSpotifyService;
     private String mCurrentQuery;
     private Player mPlayer;
+
     private ServiceConnection mServiceConnection = new ServiceConnection() {
         @Override
         public void onServiceConnected(ComponentName name, IBinder service) {
@@ -44,6 +45,23 @@ public void onServiceDisconnected(ComponentName name) {
         }
     };
 
+    private LinearLayoutManager mLayoutManager = new LinearLayoutManager(this);
+    private ScrollListener mScrollListener = new ScrollListener(mLayoutManager);
+    ;
+
+    private class ScrollListener extends ResultListScrollListener {
+
+        public ScrollListener(LinearLayoutManager layoutManager) {
+            super(layoutManager);
+        }
+
+        @Override
+        public void onLoadMore() {
+            Log.d(TAG, "Load more...");
+            mAdapter.getNextPage();
+        }
+    }
+
     public static Intent createIntent(Context context) {
         return new Intent(context, MainActivity.class);
     }
@@ -92,7 +110,7 @@ private void setupSearch() {
             public boolean onQueryTextSubmit(String query) {
                 logMessage("query text submit " + query);
                 search(query);
-                return false;
+                return true;
             }
 
             @Override
@@ -110,29 +128,16 @@ public void onItemSelected(View itemView, Track item) {
             }
         });
 
-        final LinearLayoutManager layoutManager = new LinearLayoutManager(this);
-        mResultsList.setLayoutManager(layoutManager);
+        mResultsList.setLayoutManager(mLayoutManager);
         mResultsList.setAdapter(mAdapter);
-        mResultsList.addOnScrollListener(new RecyclerView.OnScrollListener() {
-            @Override
-            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
-                super.onScrolled(recyclerView, dx, dy);
-                Log.d(TAG, "scrolled " + dx + " " + dy);
-
-                int itemCount = layoutManager.getItemCount();
-                int itemPosition = layoutManager.findLastVisibleItemPosition();
-
-                if (itemCount <= itemPosition) {
-                    Log.d(TAG, "bottom hit");
-                }
-            }
-        });
+        mResultsList.addOnScrollListener(mScrollListener);
     }
 
     private void search(@NonNull String query) {
-        if (!query.isEmpty()) {
-            mAdapter.searchTracks(query);
+        if (!query.isEmpty() && !query.equals(mCurrentQuery)) {
             mCurrentQuery = query;
+            mScrollListener.reset();
+            mAdapter.searchTracks(query, 20);
         }
     }
 
@@ -196,4 +201,5 @@ private void logMessage(String msg) {
         Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
         Log.d(TAG, msg);
     }
+
 }

app/src/main/java/com/spotify/sdk/android/ResultListScrollListener.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2015 Spotify AB
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+
+package com.spotify.sdk.android;
+
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.util.Log;
+
+public abstract class ResultListScrollListener extends RecyclerView.OnScrollListener {
+
+    private static final String TAG = ResultListScrollListener.class.getSimpleName();
+
+    private final LinearLayoutManager mLayoutManager;
+
+    private int mItemCount;
+
+    private boolean mAwaitingItems = true;
+
+    public ResultListScrollListener(LinearLayoutManager layoutManager) {
+        mLayoutManager = layoutManager;
+    }
+
+    public void reset() {
+        mItemCount = 0;
+    }
+
+    @Override
+    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
+        super.onScrolled(recyclerView, dx, dy);
+
+        int itemCount = mLayoutManager.getItemCount();
+        int itemPosition = mLayoutManager.findLastVisibleItemPosition();
+
+        if (mAwaitingItems && itemCount > mItemCount) {
+            mItemCount = itemCount;
+            mAwaitingItems = false;
+        }
+
+        Log.d(TAG, String.format("loading %s, item count: %s/%s, itemPosition %s", mAwaitingItems, mItemCount, itemCount, itemPosition));
+
+        if (!mAwaitingItems && (itemCount <= itemPosition + 1)) {
+            mAwaitingItems = true;
+            onLoadMore();
+        }
+    }
+
+    public abstract void onLoadMore();
+}

app/src/main/java/com/spotify/sdk/android/SearchResultsAdapter.java

@@ -13,7 +13,9 @@
 import com.squareup.picasso.Picasso;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import kaaes.spotify.webapi.android.SpotifyService;
 import kaaes.spotify.webapi.android.models.ArtistSimple;
@@ -33,6 +35,10 @@ public class SearchResultsAdapter extends RecyclerView.Adapter<SearchResultsAdap
     private final SpotifyService mSpotifyApi;
     private final ItemSelectedListener mListener;
     private int mOffset;
+    private String mQuery;
+    private int mLimit;
+
+    private boolean mHasMoreItems = true;
 
     public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
 
@@ -65,20 +71,37 @@ public SearchResultsAdapter(Activity context, SpotifyService spotifyService, Ite
         mListener = listener;
     }
 
-    public void setData(List<Track> items) {
+    private void clearData() {
         mItems.clear();
+    }
+
+    private void addData(List<Track> items) {
         mItems.addAll(items);
         notifyDataSetChanged();
     }
 
-    public void searchTracks(String query) {
+    public void getNextPage() {
+        mOffset += mLimit;
+        getData();
+    }
+
+    public void searchTracks(String query, int pageSize) {
+        mQuery = query;
+        mLimit = pageSize;
         mOffset = 0;
-        mSpotifyApi.searchTracks(query, new Callback<TracksPager>() {
+        clearData();
+        getData();
+    }
+
+    private void getData( ) {
+        Map<String, Object> options = new HashMap<>();
+        options.put(SpotifyService.OFFSET, mOffset);
+        options.put(SpotifyService.LIMIT, mLimit);
+        mSpotifyApi.searchTracks(mQuery, options, new Callback<TracksPager>() {
             @Override
             public void success(TracksPager tracksPager, Response response) {
-                setData(tracksPager.tracks.items);
-                mOffset = tracksPager.tracks.offset + tracksPager.tracks.limit;
-                Log.d(TAG, "Whoops success " + mOffset);
+                mHasMoreItems = tracksPager.tracks.total > tracksPager.tracks.offset + tracksPager.tracks.limit;
+                addData(tracksPager.tracks.items);
             }
 
             @Override