Java – filter concurrenthashmap by value

I'm trying to filter the size of concurrenthashmap < string, LinkedList < string > > through LinkedList < string >

In other words, I want to filter out the elements in concurrenthashmap, where the size of LinkedList < string > is Greater than 4 How do I do it with Java 8?

Solution

If you have a ConcurrentMap, you can simply create an entry flow, by calling entrySet (), then calling stream (), and by maintaining the value of the filter value by more than 4 entries. Finally, you can collect it again into the built-in collectors in concurrentmap toConcurrentMap.

ConcurrentMap<String,LinkedList<String>> map = new ConcurrentHashMap<>();

ConcurrentMap<String,LinkedList<String>> result = 
    map.entrySet()
       .stream()
       .filter(e -> e.getValue().size() > 4)
       .collect(Collectors.toConcurrentMap(Map.Entry::getKey,Map.Entry::getValue));

Alternatively, you can do this in place by modifying the map

map.values().removeIf(l -> l.size() <= 4);