HashMap键值对方法

解题思路:

注意事项:

参考代码:

import java.util.HashMap;

import java.util.Map;

import java.util.Scanner;

public class Main {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

String wordString = scanner.nextLine();

boolean flag = true;

Map<Character,Integer> pairs = new HashMap<>();

for (int i = 0; i < wordString.length(); i++) {

pairs.put(wordString.charAt(i), 0);

}

for (int i = 0; i < wordString.length(); i++) {

int num = pairs.get(wordString.charAt(i)) + 1;

pairs.put(wordString.charAt(i), num);

}

for (Map.Entry<Character, Integer> entry:pairs.entrySet()) {

if(entry.getValue() == 1) {

System.out.println(entry.getKey());

flag = false;

break;

}

}

if(flag) System.out.println("no");

}

}