用JAVA面对对象的知识，写一个选班长的投票系统

以下是一个用Java面向对象的投票系统，用于选举班长：

1. 创建一个名为Candidate的类，该类包含候选人的姓名、年龄、性别和得票数。

public class Candidate {
    private String name;
    private int age;
    private String gender;
    private int voteCount;
    
    public Candidate(String name, int age, String gender) {
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.voteCount = 0;
    }
    
    public String getName() {
        return name;
    }
    
    public int getAge() {
        return age;
    }
    
    public String getGender() {
        return gender;
    }
    
    public int getVoteCount() {
        return voteCount;
    }
    
    public void addVote() {
        voteCount++;
    }
}

2. 创建一个名为VotingSystem的类，该类包含候选人列表和投票方法。

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class VotingSystem {
    private List<Candidate> candidates;
    private Map<String, Candidate> candidateMap;
    
    public VotingSystem() {
        candidates = new ArrayList<Candidate>();
        candidateMap = new HashMap<String, Candidate>();
    }
    
    public void addCandidate(Candidate candidate) {
        candidates.add(candidate);
        candidateMap.put(candidate.getName(), candidate);
    }
    
    public void vote(String candidateName) {
        if (candidateMap.containsKey(candidateName)) {
            Candidate candidate = candidateMap.get(candidateName);
            candidate.addVote();
        } else {
            System.out.println("Candidate not found: " + candidateName);
        }
    }
    
    public Candidate getWinner() {
        Candidate winner = null;
        for (Candidate candidate : candidates) {
            if (winner == null || candidate.getVoteCount() > winner.getVoteCount()) {
                winner = candidate;
            }
        }
        return winner;
    }
}

3. 在主方法中，创建一个VotingSystem对象，并添加候选人。然后，让用户输入投票结果，并将结果记录在VotingSystem对象中。最后，输出获胜者的姓名。

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        VotingSystem system = new VotingSystem();
        
        Candidate candidate1 = new Candidate("Tom", 18, "Male");
        Candidate candidate2 = new Candidate("Jane", 17, "Female");
        Candidate candidate3 = new Candidate("David", 19, "Male");
        
        system.addCandidate(candidate1);
        system.addCandidate(candidate2);
        system.addCandidate(candidate3);
        
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.print("Enter candidate name to vote (or 'exit' to quit): ");
            String input = scanner.nextLine();
            if (input.equals("exit")) {
                break;
            }
            system.vote(input);
        }
        
        Candidate winner = system.getWinner();
        System.out.println("Winner: " + winner.getName());
    }
}

这个投票系统可以扩展以包含更多功能，例如记录每个投票者的选择，或者限制每个投票者只能投一票。