ThirdRatings.java

/**
 * ThirdRatings class contains 2 methods that can be used to get average ratings
 * (with/without filters) as well as additional helper methods.
 *
 * * getAverageRatings and getAverageRatingsByFilter are used to find movies that have required
 * * number of ratings, and in case with getAverageRatingsByFilter can be filtered using a range
 * * of filters provided in this program.
 * 
 * @ Konstantin Krumin
 * @ Version: 1.0 (February 19, 2020)
 */

import java.util.*;

public class ThirdRatings {
    private ArrayList<Rater> myRaters;
    
    public ThirdRatings () {
        // default constructor
        this("ratings.csv");
    }
    
    public ThirdRatings (String ratingsfile) {
        FirstRatings firstRatings = new FirstRatings ();
        myRaters = firstRatings.loadRaters(ratingsfile);
    }
    
    public int getRaterSize () {
        return myRaters.size();
    }
    
    private double getAverageByID (String id, int minimalRaters) {
        double sum = 0.0;
        int count = 0;
       
        for (Rater rater : myRaters) {
            if (rater.hasRating(id)) {
                sum += rater.getRating(id);
                count += 1;
            }
        }
        
        if (count >= minimalRaters) {
            return sum / count;
        } else {
            return 0.0;
        }
    }
    
    public ArrayList<Rating> getAverageRatings (int minimalRaters) {
        ArrayList<String> movies = MovieDatabase.filterBy(new TrueFilter());
        ArrayList<Rating> averageRatings = new ArrayList<Rating> ();
        
        for (String movieID : movies) {
            double average = Math.round(getAverageByID(movieID, minimalRaters) * 100.0) / 100.0;
            if (average != 0.0) {
                Rating rating = new Rating (movieID, average);
                averageRatings.add(rating);
            }
        }
        
        return averageRatings;
    }
    
    public ArrayList<Rating> getAverageRatingsByFilter (int minimalRaters, Filter filterCriteria) {
        ArrayList<Rating> averageRatings = new ArrayList<Rating> ();
        ArrayList<String> filteredMovies = MovieDatabase.filterBy(filterCriteria);
        
        for (String movieID : filteredMovies) {
            double average = Math.round(getAverageByID(movieID, minimalRaters) * 100.0) / 100.0;
            if (average != 0.0) {
                Rating rating = new Rating (movieID, average);
                averageRatings.add(rating);
            }
        }
        
        return averageRatings;
    }
}