使用 groovy 语法定义的 HashMap 不适用于字符键

Question

Does groovy not have matured support for generics? If I am explicitly saying I want a Map<Character, Character> will it not respect it?

The below code fails because map.get(Character) is giving me null. When I use Map<String, String> it works.

String eq = "{([])}"
Map<Character, Character> map =   [ '}':'{', ')': '(', ']': '[' ]
Stack<Character> stack = new Stack();
Character[] arr = eq.toCharArray();
for (int i = 0 ; i < arr.length; i++) {
    Character c = arr[i]
    if (stack.isEmpty()) {
        stack.push(c)
    } else { // check for the end
        char c1 = stack.peek()
        **// map.get(c) is null here**
        if (c1 == map.get(c)){ 
            stack.pop()
        } else {
            stack.push(c)
        }
    }
}

if (stack.isEmpty()) {
    println "Balanced Eq"
} else {
    println "Not Balanced Eq"
}

Answer 1

Groovy uses ' for string literals and not for chars (like Java). " -literals allow ${} replacements, ' -literals don't.

If you want those error catched, you most likely want to add TypeChecked or CompileStatic as compiler option or as annotations on the places, that depend on it. The default, "dynamic" Groovy does not care much for generics.