Question

Assume a text file called film_reviews.txt exists with the following contents:

7

Wall-E

5

The Martian

4

Wall-E

4

The Intern

3

...

The first line of the input file shows the number of reviews in the file. Afterward, each film/review p0ari is then written in subsequent lines in the file. Write a Java application which will read the contents of film_reviews.txt and produce an output file named review_averages.txt which contains the film name and the average of reviews in the file. The output file could look like the following:

Wall-e 4.3333

The Martian 5.0000

The Intern 3.6666

JAVA File

Answer 1

package HomeworkLib1;

import java.util.ArrayList;

class Movie{
        String name;
        ArrayList<Integer> ratings;
        Movie(String n){
                name = n;
                ratings = new ArrayList<Integer>();
        }
        public double getAverage() {
                double avg = 0;
                double sum = 0;
                int n = ratings.size();
                for(int i=0; i<n; i++) {
                        sum += this.ratings.get(i);
                }
                avg = sum/n;
                return avg;
        }
}

package HomeworkLib1;
import java.io.*;
import java.util.ArrayList;
public class FilmReview {

        
        public static void main(String[] args) {
                int n = 0;                                                      //No of movies
                ArrayList<Movie> movies = new ArrayList<Movie>();   //List of movies
                try {
                        File myfile = new File("src/HomeworkLib1/review.txt");
                        FileReader filereader = new FileReader(myfile);
                        BufferedReader reader = new BufferedReader(filereader);
                        n = Integer.parseInt(reader.readLine());                        //First line
                        
                        String line = "";
                        
                        while((line=reader.readLine())!=null) {
                                Movie m = new Movie(line);                              //Create temporary movie
                                String str = reader.readLine();                 //Get rating from file
                                Integer x = Integer.parseInt(str);
                                m.ratings.add(x);                                               //Set rating
                                //Check if a movie with this name already exists in the list
                                int i;
                                for(i=0; i<movies.size(); i++) {
                                        //line contains movie name, if it's a match, break
                                        //i contains the index of that movie
                                        if(movies.get(i).name.contentEquals(line))
                                                break;
                                }
                                if(i<movies.size()) {                                        //Match was found in the list
                                        movies.get(i).ratings.add(x);           //Add rating
                                }else {                                                                 //Match was not found
                                        movies.add(m);
                                }
                        }
                        reader.close();
                }catch(IOException e) {
                        e.printStackTrace();
                }
                try {
                        File myFile = new File("src/HomeworkLib1/review_averages.txt");
                        FileWriter fileWriter = new FileWriter(myFile);
                        BufferedWriter writer = new BufferedWriter(fileWriter);
                        
                        int i = 0;
                        for(i=0; i<movies.size(); i++) {
                                String name = movies.get(i).name;
                                double average = movies.get(i).getAverage();
                                writer.write(name + " " + average + "\n");
                        }
                        writer.close();
                }catch(IOException e) {
                        e.printStackTrace();
                }
        }
}