Design Compressed String Iterator

Design and implement a data structure for a compressed string iterator. It should support the following operations: next and hasNext.

The given compressed string will be in the form of each letter followed by a positive integer representing the number of this letter existing in the original uncompressed string.

next() - if the original string still has uncompressed characters, return the next letter; Otherwise return a white space.
hasNext() - Judge whether there is any letter needs to be uncompressed.

Note:
Please remember to RESET your class variables declared in StringIterator, as static/class variables are persisted across multiple test cases. Please see here for more details.

Example:

StringIterator iterator = new StringIterator("L1e2t1C1o1d1e1");

iterator.next(); // return 'L'
iterator.next(); // return 'e'
iterator.next(); // return 'e'
iterator.next(); // return 't'
iterator.next(); // return 'C'
iterator.next(); // return 'o'
iterator.next(); // return 'd'
iterator.hasNext(); // return true
iterator.next(); // return 'e'
iterator.hasNext(); // return false
iterator.next(); // return ' '

public class StringIterator {
    int i;
    String[] arr;
    int[] counts;

    public StringIterator(String str) {
        arr = str.split("\\d+");
        counts = Arrays.stream(str.substring(1).split("[a-zA-Z]+")).mapToInt(Integer::parseInt).toArray();
    }

    public char next() {
        if (!hasNext()) {
            return ' ';
        }
        char ch = arr[i].charAt(0);
        counts[i]--;

        if (counts[i] == 0) {
            ++i;
        }
        return ch;
    }

    public boolean hasNext() {
        if (i == arr.length) {
            return false;
        }
        return true;
    }
}