How can I sort a LinkedHashMap in Java?

How can I sort a LinkedHashMap in Java?

To sort a LinkedHashMap, you can convert it to a stream, sort the entries, and then collect them back into a LinkedHashMap.

Can you show me a code example?

Sure! Here's a simple example:

LinkedHashMap<String, Integer> map = new LinkedHashMap<>();
map.put("apple", 3);
map.put("banana", 1);
map.put("orange", 2);

LinkedHashMap<String, Integer> sortedMap = map.entrySet()
    .stream()
    .sorted(Map.Entry.comparingByValue())
    .collect(Collectors.toMap(
        Map.Entry::getKey,
        Map.Entry::getValue,
        (e1, e2) -> e1,
        LinkedHashMap::new
    ));

This will sort the map by its values.

What if I want to sort it by keys instead?

You can sort by keys by changing the comparator in the sorted method:

LinkedHashMap<String, Integer> sortedByKey = map.entrySet()
    .stream()
    .sorted(Map.Entry.comparingByKey())
    .collect(Collectors.toMap(
        Map.Entry::getKey,
        Map.Entry::getValue,
        (e1, e2) -> e1,
        LinkedHashMap::new
    ));

Is there a way to sort it in descending order?

Yes! You can use Comparator.reverseOrder() to sort in descending order. For example:

LinkedHashMap<String, Integer> sortedDescending = map.entrySet()
    .stream()
    .sorted(Map.Entry.comparingByValue(Comparator.reverseOrder()))
    .collect(Collectors.toMap(
        Map.Entry::getKey,
        Map.Entry::getValue,
        (e1, e2) -> e1,
        LinkedHashMap::new
    ));