Java实现投票统计功能教程

class Candidate {
    private String name;
    private int votes;
public Candidate(String name) {
    this.name = name;
    this.votes = 0;
}

public void incrementVote() {
    this.votes++;
}

public String getName() {
    return name;
}

public int getVotes() {
    return votes;
}

@Override
public String toString() {
    return name + ": " + votes + " 票";
}
}

import java.util.*;
public class VotingSystem {
private Map candidates;
private Set hasVoted; // 记录已投票的用户ID，防止重复投票
public VotingSystem() {
    candidates = new HashMap<>();
    hasVoted = new HashSet<>();
}

// 添加候选人
public void addCandidate(String name) {
    candidates.put(name, new Candidate(name));
}

// 用户投票，userId用于去重，choice为候选人姓名
public boolean vote(String userId, String choice) {
    if (hasVoted.contains(userId)) {
        System.out.println("用户 " + userId + " 已投过票！");
        return false;
    }

    Candidate candidate = candidates.get(choice);
    if (candidate == null) {
        System.out.println("候选人 " + choice + " 不存在！");
        return false;
    }

    candidate.incrementVote();
    hasVoted.add(userId);
    System.out.println("用户 " + userId + " 投票给 " + choice);
    return true;
}

// 显示当前投票结果
public void showResults() {
    System.out.println("\n--- 当前投票结果 ---");
    candidates.values().forEach(System.out::println);
}

// 获取得票最高的候选人
public Candidate getWinner() {
    return Collections.max(candidates.values(), Comparator.comparing(Candidate::getVotes));
}
}

public class Main {
    public static void main(String[] args) {
        VotingSystem vs = new VotingSystem();
        vs.addCandidate("张三");
        vs.addCandidate("李四");
        vs.addCandidate("王五");
    vs.vote("user1", "张三");
    vs.vote("user2", "李四");
    vs.vote("user3", "张三");
    vs.vote("user1", "李四"); // 重复投票，应被拒绝

    vs.showResults();

    Candidate winner = vs.getWinner();
    System.out.println("当前领先者: " + winner);
}
}