Average Students Grades - TreeMap<String, List<Double>>

package com.company;


import java.io.IOException;


import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.util.*;
import java.util.stream.Collectors;

public class Main {


    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);


        int n = Integer.parseInt(scanner.nextLine());

        TreeMap<String, List<Double>> studentWithGrades = new TreeMap<>();


        for (int i = 0; i < n; i++) {
            String[] input = scanner.nextLine().split(" ");
            String name = input[0];
            double grade = Double.parseDouble(input[1]);


            if (!studentWithGrades.containsKey(name)) {
                studentWithGrades.put(name, new ArrayList<>());
                studentWithGrades.get(name).add(grade);
            } else {
                studentWithGrades.get(name).add(grade);

            }

        }

        for (Map.Entry<String, List<Double>> entry : studentWithGrades.entrySet()) {
            String studentName = entry.getKey();
            List<Double> grades = entry.getValue();
            double average = grades.stream().mapToDouble(Double::doubleValue).average().getAsDouble();

//            String gradesAsString = "";
//            for (int i = 0; i < grades.size(); i++) {
//
//                gradesAsString += grades.get(i) + " ";
//            }
            //System.out.print(gradesAsString);

            System.out.printf("%s -> ", studentName);

            for (Double grade : grades) {
                System.out.print(String.format("%.2f ", grade));
            }


            System.out.printf("(avg: %.2f)%n", average);
        }


    }

}