Switch to using RecyclerView instead of ListView

Author: Roger Hu

app/build.gradle

@@ -21,6 +21,7 @@ android {
 dependencies {
     testImplementation 'junit:junit:4.12'
     implementation 'com.android.support:appcompat-v7:27.1.1'
+    implementation 'com.android.support:recyclerview-v7:27.1.1'
     implementation 'com.loopj.android:android-async-http:1.4.9'
     implementation 'com.github.bumptech.glide:glide:4.7.1'
     implementation group: 'com.google.guava', name: 'guava', version: '18.0'

app/src/main/java/com/codepath/debuggingchallenges/activities/MoviesActivity.java

@@ -2,7 +2,7 @@
 
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
-import android.widget.ListView;
+import android.support.v7.widget.RecyclerView;
 
 import com.codepath.debuggingchallenges.R;
 import com.codepath.debuggingchallenges.adapters.MoviesAdapter;
@@ -22,21 +22,21 @@ public class MoviesActivity extends AppCompatActivity {
 
     private static final String API_KEY = "a07e22bc18f5cb106bfe4cc1f83ad8ed";
 
-    ListView lvMovies;
+    RecyclerView rvMovies;
     MoviesAdapter adapter;
     ArrayList<Movie> movies;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_movies);
-        lvMovies = (ListView) findViewById(R.id.lvMovies);
+        rvMovies = findViewById(R.id.rvMovies);
 
         // Create the adapter to convert the array to views
-        MoviesAdapter adapter = new MoviesAdapter(this, movies);
+        MoviesAdapter adapter = new MoviesAdapter(movies);
 
         // Attach the adapter to a ListView
-        lvMovies.setAdapter(adapter);
+        rvMovies.setAdapter(adapter);
 
         fetchMovies();
     }

app/src/main/java/com/codepath/debuggingchallenges/adapters/MoviesAdapter.java

@@ -3,6 +3,8 @@
 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Color;
+import android.support.annotation.NonNull;
+import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -16,44 +18,72 @@
 
 import java.util.List;
 
-public class MoviesAdapter extends ArrayAdapter<Movie> {
+public class MoviesAdapter extends RecyclerView.Adapter<MoviesAdapter.ViewHolder> {
 
-    public MoviesAdapter(Context context, List<Movie> movies) {
-        super(context, 0, movies);
+    private List<Movie> movies;
+
+    public class ViewHolder extends RecyclerView.ViewHolder {
+        // only needed because we need to set the background color
+        View view;
+
+        // Lookup view for data population
+        TextView tvName;
+        TextView tvRating;
+        ImageView ivPoster;
+
+        public ViewHolder(View itemView) {
+            super(itemView);
+
+            view = itemView;
+            tvName = itemView.findViewById(R.id.tvTitle);
+            tvRating = itemView.findViewById(R.id.tvRating);
+            ivPoster = itemView.findViewById(R.id.ivPoster);
+        }
+    }
+
+    public MoviesAdapter(List<Movie> movies) {
+        this.movies = movies;
     }
 
     @Override
-    public View getView(int position, View convertView, ViewGroup parent) {
-        // Get the data item for this position
-        Movie movie = getItem(position);
-        // Check if an existing view is being reused, otherwise inflate the view
-        if (convertView == null) {
-            convertView = LayoutInflater
-                    .from(getContext())
-                    .inflate(R.layout.item_movie, parent, false);
-        }
-        // Lookup view for data population
-        TextView tvName = (TextView) convertView.findViewById(R.id.tvTitle);
-        TextView tvRating = (TextView) convertView.findViewById(R.id.tvRating);
-        ImageView ivPoster = (ImageView) convertView.findViewById(R.id.ivPoster);
+    public int getItemCount() {
+        return 0;
+    }
+
+    @NonNull
+    @Override
+    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        Context context = parent.getContext();
+        LayoutInflater inflater = LayoutInflater.from(context);
+
+        // Inflate the custom layout
+        View movieView = inflater.inflate(R.layout.item_movie, parent, false);
+
+        // Return a new holder instance
+        ViewHolder viewHolder = new ViewHolder(movieView);
+        return viewHolder;
+    }
+
+    @Override
+    public void onBindViewHolder(MoviesAdapter.ViewHolder viewHolder, int position) {
 
+        Movie movie = movies.get(position);
 
         // Populate the data into the template view using the data object
-        tvName.setText(movie.getTitle());
+        viewHolder.tvName.setText(movie.getTitle());
 
-        Resources resources = getContext().getResources();
+        Resources resources = viewHolder.tvName.getResources();
         double movieRating = movie.getRating();
 
         if (movieRating > 6) {
-            convertView.setBackgroundColor(Color.GREEN);
+            viewHolder.view.setBackgroundColor(Color.GREEN);
         }
 
         String ratingText = String.format(resources.getString(R.string.rating), movieRating);
-        tvRating.setText(ratingText);
+        viewHolder.tvRating.setText(ratingText);
 
-        Glide.with(getContext()).load(movie.getPosterUrl()).into(ivPoster);
+        Glide.with(viewHolder.ivPoster.getContext()).load(movie.getPosterUrl()).into(
+                viewHolder.ivPoster);
 
-        // Return the completed view to render on screen
-        return convertView;
     }
 }

app/src/main/res/layout/activity_movies.xml

@@ -1,18 +1,19 @@
 <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:tools="http://schemas.android.com/tools"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    tools:context=".activities.MoviesActivity">
+                xmlns:app="http://schemas.android.com/apk/res-auto"
+                xmlns:tools="http://schemas.android.com/tools"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                tools:context=".activities.MoviesActivity">
 
-    <ListView
+    <android.support.v7.widget.RecyclerView
+        android:id="@+id/rvMovies"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        android:id="@+id/lvMovies"
-        android:layout_alignParentTop="true"
-        android:layout_alignParentLeft="true"
         android:layout_alignParentStart="true"
-        android:layout_alignParentBottom="true"
+        android:layout_alignParentLeft="true"
+        android:layout_alignParentTop="true"
+        android:layout_alignParentEnd="true"
         android:layout_alignParentRight="true"
-        android:layout_alignParentEnd="true" />
+        android:layout_alignParentBottom="true"/>
 </RelativeLayout>