Question

    private java.util.HashMap<Character, Boolean> letters = new java.util.HashMap<Character, Boolean>();

    for (int i = 0; i < 26; i++) {
        letters.put(letter, false);
        System.out.println(letter);
        letter++;
    }
    for (Map.Entry<Character, Boolean> v : letters.entrySet()) {
        System.out.println(v.getKey());
    }

When print the letter I can get a b c d e f g …..but after store in the hashmap it return me f g d e b c….. not in sequence why?

Answer 1

HashMap is not ordered. If you want to retrieve the entries in the insertion order, use LinkedHashMap instead.