java - ArrayList 访问器方法不返回任何值

Question

这是我在自己的类(class)中制作的第一个程序。它旨在执行单一可转让选举；现在我需要获得一个ArrayList<Candidate>的Candidate对象。在构造函数内部，该过程运行得很好；但是，一旦我尝试使用访问器方法，就会出现空 ArrayList被返回。这是代码:

import java.util.*;
public class Election {

    public ArrayList<Candidate> candidates = new ArrayList<Candidate>();

    Election(int numVotes) {
        String name;
        ArrayList<Candidate> candidates = new ArrayList<Candidate>();
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Enter the candidates you want in the election.");
        System.out.println("Enter -1 once you have listed all the candidates.");
        System.out.print("Start entering candidates: ");
        name = keyboard.nextLine();
        while (!name.equals("-1")) {
            candidates.add(new Candidate(name));
            System.out.print("Ok, enter a new candidate or -1: ");
            name = keyboard.nextLine();

        }

        //Works fine here
    }

    public ArrayList<Candidate> getCandidateList() {   
        //Keeps returning empty list
        //System.out.println(candidates);
        return this.candidates;    
    }
} 

Answer 1

public ArrayList<Candidate> candidates = new ArrayList<Candidate>();
Election(int numVotes)
{
    String name;
    ArrayList<Candidate> candidates = new ArrayList<Candidate>();
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

您正在创建一个不同数组列表并“隐藏”candidates成员变量。应该是

    this.candidates = new ArrayList<Candidate>();