java - 列表中的调用长度和列表的特定项目

Question

请查看我想要描述的场景的图片。

我想要在列表中包含一个列表，并知道该列表(内部)的大小以及如何从该列表中调用特定数据。--另请包括如何添加 hobbyList进入candidateList

假设我想将第二个候选者的 hobbyList 大小称为 <code>CandidateList(1).HobbyList.length()</code> ？或.size() ？

如果我想调用第二个候选人的第三个爱好的值怎么办 CandidateList(1).HobbyList(2) ？

我不知道我是否已经清楚自己想要什么，所以请随时询问我。

谢谢! :)

Answer 1

爱好类

public class Hobby {
    private int id;
    private String hobby;

    public Hobby(int id, String hobby) {
        this.id = id;
        this.hobby = hobby;
    }
    // Getters and setters
}

候选人类(class)

import java.util.List;
public class Candidate {
    private int id;
    private String candidateName;
    private List<Hobby> hobbies;

    public Candidate(int id, String candidateName, List<Hobby> hobbies) {
        this.id = id;
        this.candidateName = candidateName;
        this.hobbies = hobbies;
    }
    // Getters and setters
}

MainClassDemo 具有 main 方法

import java.util.ArrayList;
import java.util.List;
public class MainClassDemo {
    public static void main(String[] args) {
        Hobby c1Hb1 = new Hobby(1, "Cricket");
        Hobby c1Hb2 = new Hobby(2, "Hockey");
        Hobby c1Hb3 = new Hobby(3, "Football");
        List<Hobby> hobbies1 = new ArrayList<Hobby>();
        hobbies1.add(c1Hb1);
        hobbies1.add(c1Hb2);
        hobbies1.add(c1Hb3);
        Candidate candidate1 = new Candidate(1, "Ankit", hobbies1);

        Hobby c2Hb1 = new Hobby(4, "FB");
        Hobby c2Hb2 = new Hobby(5, "TW");
        Hobby c2Hb3 = new Hobby(6, "INSTA");
        Hobby c2Hb4 = new Hobby(6, "Pininterest");
        Hobby c2Hb5 = new Hobby(6, "Quara");
        List<Hobby> hobbies2 = new ArrayList<Hobby>();
        hobbies2.add(c2Hb1);
        hobbies2.add(c2Hb2);
        hobbies2.add(c2Hb3);
        hobbies2.add(c2Hb4);
        hobbies2.add(c2Hb5);
        Candidate candidate2 = new Candidate(2, "Bhumi", hobbies2);

        List<Candidate> candidateList = new ArrayList<Candidate>();
        candidateList.add(candidate1);
        candidateList.add(candidate2);

        System.out.println("No of Candidates:->" + candidateList.size());
        System.out.println("Hobby list size for the 1st Candidate:->" + candidateList.get(0).getHobbies().size());
        System.out.println("Hobby list size for the 2nd Candidate:->" + candidateList.get(1).getHobbies().size());

        System.out.println("1st Hobby of 1st Candidate:->" + candidateList.get(0).getHobbies().get(0).getHobby());
        System.out.println("3rd Hobby of 2nd Candidate:->" + candidateList.get(1).getHobbies().get(2).getHobby());
    }
}

输出

候选人数量:->2
第一个候选人的爱好列表大小:->3
第二位候选人的爱好列表大小:->5
第一候选人的第一爱好:->板球
第二名候选人的第三个爱好:->INSTA