编辑代码

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

public class VoteCounter {
    private Map<String, Boolean> votes;

    public VoteCounter() {
        this.votes = new HashMap<>();
    }

    public void vote(String candidate) {
        if (votes.containsKey(candidate)) {
            System.out.println("Sorry, " + candidate + " has already received your vote.");
        } else {
            votes.put(candidate, true);
            System.out.println("Vote for " + candidate + " recorded successfully.");
        }
    }

    public static void main(String[] args) {
        VoteCounter voteCounter = new VoteCounter();

        voteCounter.vote("Candidate A");  // 输出: Vote for Candidate A recorded successfully.
        voteCounter.vote("Candidate B");  // 输出: Vote for Candidate B recorded successfully.
        voteCounter.vote("Candidate A");  // 输出: Sorry, Candidate A has already received your vote.
    }
}