java - 插入 Hashtable>

Question

我不确定为什么在我的 put 下会出现错误:

The method put(Character, List<Boolean>) in the type 
Hashtable<Character,List<Boolean>> is not applicable for the arguments (char, boolean)

我想我有所有匹配的类型

这是我的代码

    Hashtable<Character, List<Boolean>> charCheck =
         new Hashtable<Character, List<Boolean>>();
    List<Boolean> used = new ArrayList<Boolean>();
    //Set<String> nonDuplicate = new Set<String>();
    // make a hashtable of characters used
    char[] charArray = str.toCharArray(); 
    for (char c : charArray) {
        charCheck.put(c, used.add(false));

Answer 1

Java 中的 List#add 方法返回一个 boolean 指示值是否已成功添加到 List 中。您应该将向 Map 添加新的 List 与向其添加新元素分开:

Hashtable<Character, List<Boolean>> charCheck = new Hashtable<Character, List<Boolean>>();
char[] charArray = str.toCharArray(); 

for (char c : charArray) {
    List<Boolean> used = charCheck.get(c);

    // If the char isn't in the map yet, add a new list
    if (used == null) {
        used = new ArrayList<Boolean>();
        charCheck.put (c, used);
    }

    used.add(false);
}