https://www.acmicpc.net/problem/10814

나이순 정렬.java

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        StringBuilder sb = new StringBuilder();
        int N = sc.nextInt();
        String [][]member = new String[N][2];
        for(int i=0; i<N; i++){
            member[i][0] = sc.next(); // 나이
            member[i][1] = sc.next(); // 이름
        }
        sc.close();
        Arrays.sort(member, new Comparator<String[]>() {
            @Override
            public int compare(String[] a, String[] b){
                return Integer.parseInt(a[0])-Integer.parseInt(b[0]); // 나이만 비교합니다.
            }
        });
        for (String[] strings : member)
            sb.append(strings[0] + " " + strings[1]+"\n");
        System.out.print(sb);
    }
}