编辑代码

import java.util.HashMap;
import java.util.Map;

class Main {
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<>();

        vote(map, "王五", "赵六");
        vote(map, "赵六", "钱七");
        vote(map, "王五", "钱七");

        for (Map.Entry<String, String> entry : map.entrySet()) {
            System.out.println(entry.getKey() + ":" + entry.getValue());
        }
    }

    public static void vote(Map<String, String> map, String name, String candidate) {
        if (!map.containsKey(name)) {
            map.put(name, candidate);
        }
    }
}