java - HashMap>

Question

我试图让 HashMap 存储一个字符串和一个 ArrayList<String>.基本上我想要的是第一个字符串是一个名称，数组列表包含用户去过的每个国家/地区。

Example:
{Andrew, [USA, China]}
{Lola, [Sweden, Denmark]}

我遇到的问题是每当用户输入一个国家时，这个国家将被存储在两个名字下:

"The HashMap contains: {Andrew=[USA, China, Sweden, Denmark], Lola=[USA, China, Sweden, Denmark]}"

ArrayList<String> namelist = new ArrayList<>();
ArrayList<String> test = new ArrayList<>();
ArrayList<String> archive = new ArrayList<>();
HashMap<String, ArrayList<String>> thearchive = new HashMap<>();

(input.equals("New Country")){
    System.out.println("Name of the Person? ");
    String name = in.nextLine();
    if(namelist.contains(name)){
        System.out.println("Which Country have you visited?");
        String country = in.nextLine();
        if (archive.contains(country)){
            System.out.println("You've already visited this country.");
        }
        else {
            test.add(country);
            thearchive.put(name, country);
            System.out.println("HashMap Contains: " + thearchive);
        }
    }
    else{
        System.out.println("The person does not exist please add first.");
    }

有人知道为什么 HashMap 没有按照我想要的方式存储键/值吗？

Answer 1

你的代码还没有完成，所以我不知道什么是测试存档。但是让我们创建一个示例:

HashMap<String, ArrayList<String>> list = new HashMap<String, ArrayList<String>>();
ArrayList<String> anotherlist = new ArrayList<String>();
anotherlist.add("Brazil");
anotherlist.add("USA");
list.put("Augusto", anotherlist);

希望对你有帮助。