백준 1181번 :: 단어 정렬

import java.io.*;
import java.util.Arrays;
import java.util.Comparator;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        int N = Integer.parseInt(br.readLine());
        String[] arr = new String[N];
        for (int i = 0; i < N; i++) {
            arr[i] = br.readLine();
        }
        Arrays.sort(arr, new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
                if (o1.length() == o2.length()) {
                    return o1.compareTo(o2);
                } else {
                    return o1.length() - o2.length();
                }
            }
        });
        bw.write(arr[0] + "\n");
        for (int i = 1; i < N; i++) {
            if (!arr[i].equals(arr[i - 1])) {
                bw.write(arr[i] + "\n");
            }
        }
        bw.flush();
        bw.close();
    }
}

https://st-lab.tistory.com/243

자바 [JAVA] - Comparable 과 Comparator의 이해