Week3. Create a new class named ThirdRatings.

Author: SkyrocketStan

Week3/src/FirstRatings.java

@@ -212,7 +212,7 @@ private int totalComedy() {
   }
 
   // Make full filename for any OS types
-  private String getFullFileName(String fileName) {
+  private static String getFullFileName(String fileName) {
     if (!(new File(fileName).exists())) {
       fileName =
           System.getProperty("user.dir") + File.separator + "data" + File.separator + fileName;
@@ -346,7 +346,7 @@ private void printAllRatingsByRater(String raterID) {
    * This method should process every record from the CSV file whose name is
    * filename, a file of raters and their ratings
    */
-  private ArrayList<Rater> loadRaters(String fileName) {
+  static ArrayList<Rater> loadRaters(String fileName) {
     ArrayList<Rater> ratersList = new ArrayList<>();
     ArrayList<String> idsList = new ArrayList<>();
 

Week3/src/ThirdRatings.java

@@ -0,0 +1,45 @@
+import java.util.ArrayList;
+
+public class ThirdRatings {
+
+  private final ArrayList<Rater> myRaters;
+  private ArrayList<String> allMoviesIDs;
+
+  public ThirdRatings() {
+    this("ratings.csv");
+    allMoviesIDs = MovieDatabase.filterBy(new TrueFilter());
+  }
+
+  public ThirdRatings(String ratingsFileName) {
+    this.myRaters = FirstRatings.loadRaters(ratingsFileName);
+  }
+
+  public ArrayList<Rating> getAverageRatings(int minimalRaters) {
+    ArrayList<Rating> list = new ArrayList<>();
+    for (String movieID : allMoviesIDs) {
+      Double averageRating = getAverageByID(movieID, minimalRaters);
+      if (averageRating != 0.0) {
+        list.add(new Rating(movieID, averageRating));
+      }
+    }
+    return list;
+  }
+
+  /*
+  This method returns a double representing the average movie rating for this ID
+  if there are at least minimalRaters ratings.
+  If there are not minimalRaters ratings, then it returns 0.0.
+  */
+  Double getAverageByID(String movieID, Integer minimalRaters) {
+    long numOfRatings = myRaters.stream().filter(rater -> rater.hasRating(movieID)).count();
+
+    if (numOfRatings >= minimalRaters) {
+      return myRaters.stream()
+          .filter(rater -> rater.hasRating(movieID))
+          .mapToDouble(rating -> rating.getRating(movieID))
+          .average()
+          .orElse(0.0);
+    }
+    return 0.0;
+  }
+} // class