使用比较器 class 创建一个数组

Question

I know how to create a priority Queue with the comparator class. Here I created a comparator class to compare 2 characters. My question is that how should I create a char array with the comparing methods? I tried the following: char[] helper = new char[](new StringNumComparator()); .

 public String Practice(String input) {
        class StringNumComparator implements Comparator<Character> {
            @Override
            public int compare(Character a, Character b) {
                if (Character.isAlphabetic(a) && Character.isAlphabetic(b)) {
                    return (int) a <= (int) b ? -1 : 1;
                } else if (Character.isDigit(a) && Character.isDigit(b)) {
                    return Character.getNumericValue(a) <= Character.getNumericValue(b) ? -1 : 1;
                }
                return Character.isAlphabetic(a) ? -1 : 1;
            }
        }

        char[] helper = new char[](new StringNumComparator());
        return new String(helper);
}

Answer 1

There is no such concept as an "always-sorted array" in Java like it seems you're trying to create. You could explicitly sort an array using a customer comparator:

Arrays.sort(myArray, new StringNumComparator());

But note this only applies to arrays of objects (like Character ), not primitives (like char ).

Answer 2

this is invalid in java:

char[] helper = new char[](new StringNumComparator());

instead you can create the array and later sort it calling the help method (static method) of the class Arrays

char[] helper = ...your array
Arrays.sort(helper, new StringNumComparator());