Iterating through a LinkedHashMap in reverse order

The HashMap:

HashMap<Integer, String> map = new HashMap<Integer, String>();

Reverse iterating over values:

ListIterator<Sprite> iterator = new ArrayList<String>(map.values()).listIterator(map.size());
while (iterator.hasPrevious()) String value = iterator.previous();

Reverse iterating over keys:

ListIterator<Integer> iterator = new ArrayList(map.keySet()).listIterator(map.size());
while (iterator.hasPrevious()) Integer key = iterator.previous();

Reverse iterating over both:

ListIterator<Map.Entry<Integer, String>> iterator = new ArrayList<Map.Entry<Integer, String>>(map.entrySet()).listIterator(map.size());
while (iterator.hasPrevious()) Map.Entry<Integer, String> entry = iterator.previous();

new LinkedList(linkedHashMap.keySet()).descendingIterator();

The question requires a LinkedHashMap in reverse order, some answers suggesting using a TreeSet but this will reorder the map based upon the key.

This solution allows the iteration over the original LinkedHashMap not the new ArrayList as has also been proposed:

List<String> reverseOrderedKeys = new ArrayList<String>(linkedHashMap.keySet());
Collections.reverse(reverseOrderedKeys);
for (String key : reverseOrderedKeys) {
    RecordItemElement line = linkedHashMap.get(key);
}

You don't have to iterate through it. But it would be handy to pull the keys off and store it in a list. Thats the only way you can do indexOf() type operations.

List<String> keyList = new ArrayList<String>(map.keySet());
// Given 10th element's key
String key = "aKey";
int idx = keyList.indexOf(key);
for ( int i = idx ; i >= 0 ; i-- ) 
 System.out.println(map.get(keyList.get(i)));

Tags:

Java

Hashmap