Java 8 simple input validation with quotes

InputValidationFunction.java

/**
 * Function that checks whether the command line input is valid. This
 * method can handle input with spaces that are escaped inside
 * quotation marks (either " or '). However this method will throw
 * an Exception when either the input is empty or when the input
 * is malformed.
 *
 * Malformed input occurs when there are an odd number of quotation
 * marks in the input string, but only if there are more than one.
 *
 * @param input Input that should be validated.
 * @return Validated input as an array.
 * @throws NullPointerException     When the input is empty.
 * @throws IllegalArgumentException When there are an odd number
 *                                  of quotation marks.
 */
private final String[] getInput(String input) throws NullPointerException, IllegalArgumentException {
    if (input.isEmpty()) {
        throw new NullPointerException("Input cannot be empty.");
    }

    if (input.chars().filter(c -> (c == ' ')).count() == 0) {
        return new String[] { input };
    }

    if (input.chars().filter(c -> (c == '"' || c == '\'')).count() % 2 == 1) {
        throw new IllegalArgumentException("Malformed input, please check your syntax.");
    }

    int numberOfQuotes = 0;
    String currentCommand = "";
    ArrayList<String> args = new ArrayList<>();

    for (char c : input.toCharArray()) {
        if (c == '"' || c == '\'') {
            numberOfQuotes++;
            continue;
        }

        if (c == ' ' && numberOfQuotes % 2 == 0) {
            args.add(currentCommand);
            currentCommand = "";
            continue;
        }

        currentCommand += c;
    }

    if (!currentCommand.isEmpty()) {
        args.add(currentCommand);
    }

    return args.toArray(new String[0]);
}