Week3. Assignment 1: Efficiency

Author: SkyrocketStan

Week3/src/EfficientRater.java

@@ -0,0 +1,47 @@
+import java.util.ArrayList;
+import java.util.HashMap;
+
+/**
+ * The class EfficientRater keeps track of one rater and all their ratings.
+ *
+ * @author Stanislav Rakitov
+ * @version 1.0
+ */
+public class EfficientRater implements Rater {
+  private final String myID;
+  private final HashMap<String, Rating> myRatings;
+
+  public EfficientRater(String id) {
+    myID = id;
+    myRatings = new HashMap<>();
+  }
+
+  public void addRating(String movieID, Rating rating) {
+    myRatings.put(movieID, rating);
+  }
+
+  public boolean hasRating(String movieID) {
+    return myRatings.containsKey(movieID);
+  }
+
+  public String getID() {
+    return myID;
+  }
+
+  public double getRating(String movieID) {
+    Rating rating = myRatings.get(movieID);
+    if (rating != null) {
+      return rating.getValue();
+    } else {
+      return -1;
+    }
+  }
+
+  public int numRatings() {
+    return myRatings.size();
+  }
+
+  public ArrayList<String> getItemsRated() {
+    return new ArrayList<>(myRatings.keySet());
+  }
+}

Week3/src/FirstRatings.java

@@ -366,14 +366,14 @@ private ArrayList<Rater> loadRaters(String fileName) {
       double rating = Double.parseDouble(record.get(2));
       String time = record.get(3);
       if (!idsList.contains(rater_id)) {
-        Rater rater = new PlainRater(rater_id);
+        Rater rater = new EfficientRater(rater_id);
         ratersList.add(rater);
-        rater.addRating(movie_id, rating);
+        rater.addRating(movie_id, new Rating(movie_id, rating));
         idsList.add(rater_id);
       } else {
         for (Rater r : ratersList) {
           if (r.getID().equals(rater_id)) {
-            r.addRating(movie_id, rating);
+            r.addRating(movie_id, new Rating(movie_id, rating));
           }
         }
       }

Week3/src/Rater.java

@@ -1,7 +1,8 @@
 import java.util.ArrayList;
 
 public interface Rater {
-  void addRating(String item, double rating);
+  //  void addRating(String item, double rating);
+  void addRating(String movieID, Rating rating);
 
   boolean hasRating(String item);