removing from a hashmap and adding to the end

[dogeatdogfood]

hi guys,

Just come across the forum, and it seems a great place to learn for someone only just starting out in java!

Wondering if anyone can assist

I am trying to write a method that represents a rota by removing an entry in a hashmap and adding it to the end, however the code I have at the moment works for removing the entry but when I put it back it goes in its original place:

    public void cleaningRota(String justCleaned)
    {
        ArrayList<Integer> removedKey = cleanVolunteers.remove(justCleaned);
        cleanVolunteers.put(justCleaned, removedKey);
        System.out.println(removedKey);//ignore - used for testing
    }

Thanks

[doWhile]

Recommend reading on how a HashMap works under the hood - and this is clearly stated in the API

This class makes no guarantees as to the order of the map; in particular, it does not guarantee that the order will remain constant over time.

This includes the order of entry. If you need to maintain the order of entry of the keys within a Map, use a LinkedHashMap

[DarrylBurke]

HashMap is unordered, so the concept of 'adding to the end' doesn't apply. Read the API for the Map interface and go through the implementing classes; you'll find there's a Map implementation that has

predictable iteration order.

db

cat's out of the bag!