Implemented Parallax Scrolling using an onScrollListener for RecyclerView.

app/src/main/java/com/example/android/sunshine/app/ForecastFragment.java

@@ -15,12 +15,14 @@
  */
 package com.example.android.sunshine.app;
 
+import android.annotation.TargetApi;
 import android.app.Activity;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.content.res.TypedArray;
 import android.database.Cursor;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 import android.preference.PreferenceManager;
 import android.support.v4.app.Fragment;
@@ -195,6 +197,25 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
         // specify an adapter (see also next example)
         mRecyclerView.setAdapter(mForecastAdapter);
 
+        final View parallaxView = rootView.findViewById(R.id.parallax_bar);
+        if (null != parallaxView) {
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
+                mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
+                    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
+                    @Override
+                    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
+                        super.onScrolled(recyclerView, dx, dy);
+                        int max = parallaxView.getHeight();
+                        if (dy > 0) {
+                            parallaxView.setTranslationY(Math.max(-max, parallaxView.getTranslationY() - dy / 2));
+                        } else {
+                            parallaxView.setTranslationY(Math.min(0, parallaxView.getTranslationY() - dy / 2));
+                        }
+                    }
+                });
+            }
+        }
+
         // If there's instance state, mine it for useful information.
         // The end-goal here is that the user never knows that turning their device sideways
         // does crazy lifecycle related things.  It should feel like some stuff stretched out,
@@ -318,6 +339,14 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
 
     }
 
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        if (null != mRecyclerView) {
+            mRecyclerView.clearOnScrollListeners();
+        }
+    }
+
     @Override
     public void onLoaderReset(Loader<Cursor> loader) {
         mForecastAdapter.swapCursor(null);

app/src/main/res/layout-land/fragment_main.xml

@@ -19,7 +19,7 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent">
     <LinearLayout
-        android:id="@+id/appbar"
+        android:id="@+id/parallax_bar"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_alignParentTop="true"