按值过滤 ConcurrentHashMap

Question

我正在尝试按 LinkedList<String> 的大小过滤 ConcurrentHashMap<String, LinkedList<String>>。

换句话说，我想过滤掉ConcurrentHashMap中LinkedList<String>大小大于4的元素，如何通过Java8来完成？

Answer 1

如果您有一个 ConcurrentMap，您可以通过调用 entrySet() and then stream() and keep the entries where the value has a length greater than 4 by applying a filter. Finally, you can collect that again into a ConcurrentMap with the built-in Collectors.toConcurrentMap.

简单地创建其条目流

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));

或者，您可以通过使用

修改地图来就地完成

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

按值过滤 ConcurrentHashMap

Filter ConcurrentHashMap by value

java

filtering

concurrenthashmap

java-8

java-stream