// 1)

public String whatAmI(E e) {
    if (e.getClass().equals(Integer.class)) {
        return "Integer";
    } else if (e.getClass().equals(Double.class)) {
        return "Double";
    } else if (e.getClass().equals(Character.class)) {
        return "Character";
    } else if (e.getClass().equals(String.class)) {
        return "String";
    } else {
        return "Who knows!";
    }
}
// 2)

public String reverseWord(String word) {
    Stack<Character> stack = new Stack<Character>();
    for (int i = 0; i < word.length(); i++) {
        stack.push(word.charAt(i));
    }
    String result = "";
    while (!stack.isEmpty()) {
        result += stack.pop();
    }
    return result;
}