How to print keys with duplicate values in a hashmap?

Question

I have a hashmap with some keys pointing to same values. I want to find all the values that are equal and print the corresponding keys.

This is the current code that I

Answer 1

If you want a solution beside to Stream API;

    public static void duplicatedValuesMap() {
        Map map = new HashMap<>();

        map.put("hello", "0123");
        map.put("hola", "0123");
        map.put("kosta", "0123 test");
        map.put("da", "03");
        map.put("notda", "013");
        map.put("twins2", "01");
        map.put("twins22", "01");

        HashMap> valueToKeyMapCounter = new HashMap<>();

        for (Map.Entry entry : map.entrySet()) {
            if (valueToKeyMapCounter.containsKey(entry.getValue())) {
                valueToKeyMapCounter.get(entry.getValue()).add(entry.getKey());
            } else {
                List keys = new ArrayList<>();
                keys.add(entry.getKey());
                valueToKeyMapCounter.put(entry.getValue(), keys);
            }
        }
        for (Map.Entry> counterEntry : valueToKeyMapCounter.entrySet()) {
            if (counterEntry.getValue().size() > 1) {
                System.out.println("Duplicated Value:" + counterEntry.getKey() + " for Keys:" + counterEntry.getValue());
            }
        }

    }