How to create array from elements from another file in Java

Question

so I want to create an array each for the score of flyweight and featherweight. but i have no idea how. this is my code so far

Scanner readFile = new Scanner (Main.class.getResourceAsStream("boxingcompetition.txt"));
        int competition = Integer.parseInt(readFile.nextLine());
        int totalCompetition = competition *2;
        
        String line;
        String[] lineSplit;
        String name;
        int score;
        String categories;
        
        for (int i = 1; i<= totalCompetition; i++)
        {
            line = readFile.nextLine();
            lineSplit = line.split(",");
            name = lineSplit[0];
            score = Integer.parseInt(lineSplit[1]);
            categories = lineSplit[2];
            
            if (categories.equals("flyweight"))
            {}

Create a record `Boxer` with 3 fields, then fill two `List` for both weights, then sort them by score and take the last element. — f1sh, Mar 16 '23 at 17:17
what do you mean by boxer... T-T i'm sorry i'm a super beginner @f1sh — aurellia, Mar 16 '23 at 17:30
Have you learned about Java classes? Boxer would be a class (or a record as suggested by @f1sh) And another way to do this would be to use a map. — WJS, Mar 16 '23 at 17:33
Check out [The Java Tutorials](https://docs.oracle.com/javase/tutorial/index.html) for more about the basics of Java (note that `record's` won't be covered there but `classes` will). — WJS, Mar 16 '23 at 17:43

score -1 · Answer 1 · answered Mar 16 '23 at 18:00

You can utilize Java 8+ 's collection utilities to find the max values.

Just parse each line into an object and place it in a list. You can now group by division, and for each division list, locate the max. You must make sure your Boxer class implements Comparable for Collection.max to actually work.

import java.util.*;
import java.util.stream.Collectors;

public class BoxingScores {
    public static void main(String[] args) {
        BoxingCompetition competition = parseFile("/boxingcompetition.txt");
        Map<String, List<Boxer>> grouped = competition.getBoxers().stream()
                .collect(Collectors.groupingBy(Boxer::getDivision));
        List<Boxer> topScores = grouped.entrySet().stream()
                .map(Map.Entry::getValue)
                .map(Collections::max)
                .collect(Collectors.toList());
        System.out.println(topScores);
    }

    private static BoxingCompetition parseFile(String filename) {
        List<Boxer> boxers = new ArrayList<>();
        Scanner scan = new Scanner(BoxingScores.class.getResourceAsStream(filename));
        int competitions = scan.nextInt();
        scan.nextLine();
        System.out.printf("Competitions: %d%n", competitions);

        while (scan.hasNextLine()) {
            String line = scan.nextLine();
            String[] tokens = line.split(",");
            String name = tokens[0];
            int score = Integer.parseInt(tokens[1]);
            String division = tokens[2];
            boxers.add(new Boxer(name, division, score));
        }

        scan.close();

        return new BoxingCompetition(competitions, boxers);
    }

    private static class BoxingCompetition {
        private int count;
        private List<Boxer> boxers;

        public BoxingCompetition(int count, List<Boxer> boxers) {
            this.count = count;
            this.boxers = boxers;
        }

        public int getCount() {
            return count;
        }

        public void setCount(int count) {
            this.count = count;
        }

        public List<Boxer> getBoxers() {
            return boxers;
        }

        public void setBoxers(List<Boxer> boxers) {
            this.boxers = boxers;
        }
    }

    private static class Boxer implements Comparable<Boxer> {
        private String name;
        private String division;
        private int score;

        public Boxer(String name, String division, int score) {
            this.name = name;
            this.division = division;
            this.score = score;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public String getDivision() {
            return division;
        }

        public void setDivision(String division) {
            this.division = division;
        }

        public int getScore() {
            return score;
        }

        public void setScore(int score) {
            this.score = score;
        }

        @Override
        public int compareTo(Boxer other) {
            return this.score - other.score; // Descending
        }

        @Override
        public String toString() {
            return String.format("{ name: \"%s\", division: \"%s\", score: %d }", name, division, score);
        }
    }
}

Output

[
  { name: "Eva", division: "flyweight", score: 96 },
  { name: "Harry", division: "featherweight", score: 90 }
]

How to create array from elements from another file in Java

1 Answers1

Output