Java vector sort

C++ vector에서도 cmp 함수를 구현하는 것처럼 Java에서도 비슷하다.

연습문제 : https://www.acmicpc.net/problem/11650

아래는

First 먼저 오름차순 

(First가 같으면) Second 오름차순

의 구현이다.

Collections.sort(v, new Comparator<Pair>() {
            public int compare(Pair p1, Pair p2) {
                if(p1.First < p2.First) {
                    return -1;
                }
                else if(p1.First == p2.First) {
                    return Integer.compare(p1.Second, p2.Second);
                }
                else {
                    return 1;
                }
            }
        });

import java.io.*;
import java.util.*;
 
public class Main {
    
    static int n;
 
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringTokenizer st;
        
        Vector<Pair> v = new Vector<Pair>();
        
        n = Integer.parseInt(br.readLine());
        
        int x, y;
        
        for(int i=0; i<n; i++) {
            st = new StringTokenizer(br.readLine());
            
            x = Integer.parseInt(st.nextToken());
            y = Integer.parseInt(st.nextToken());
            
            v.add(new Pair(x, y));
        }
        
        Collections.sort(v, new Comparator<Pair>() {
            public int compare(Pair p1, Pair p2) {
                if(p1.First < p2.First) {
                    return -1;
                }
                else if(p1.First == p2.First) {
                    return Integer.compare(p1.Second, p2.Second);
                }
                else {
                    return 1;
                }
            }
        });
        
        for(Pair i : v) {
            System.out.println(i.First + " " + i.Second);
        }
    }
}
 
class Pair {
    
    int First, Second;
    
    Pair(int first, int second) {
        this.First = first;
        this.Second = second;
    }
}