Letter Combinations

class Solution {
    List<String> outputList = new ArrayList<>();

    public List<String> letterCombinations(String digits) {
        Map<Integer, char[]> keypadMap = new HashMap<>();

        keypadMap.put(2, new char[] { 'a', 'b', 'c' });
        keypadMap.put(3, new char[] { 'd', 'e', 'f' });
        keypadMap.put(4, new char[] { 'g', 'h', 'i' });
        keypadMap.put(5, new char[] { 'j', 'k', 'l' });
        keypadMap.put(6, new char[] { 'm', 'n', 'o' });
        keypadMap.put(7, new char[] { 'p', 'q', 'r', 's' });
        keypadMap.put(8, new char[] { 't', 'u', 'v' });
        keypadMap.put(9, new char[] { 'w', 'x', 'y', 'z' });

        int i = 0;
        char temp[] = new char[digits.length()];
        printAll(temp, i, digits, keypadMap);

        return outputList;
    }

    public void printAll(char[] temp, int i, String digits, Map<Integer, char[]> keypadMap) {
        char[] charArray = digits.toCharArray();
        if (i > charArray.length - 1 && temp != null) {
            if (temp.length != 0) {
                outputList.add(new String(temp));
            }
            return;
        }

        for (int j = 0; j < keypadMap.get(charArray[i] - '0').length; j++) {
            temp[i] = keypadMap.get(charArray[i] - '0')[j];

            printAll(temp, i + 1, digits, keypadMap);
        }

    }
}