CODEWITHSUNDEEP
javacollections
reiley
reiley

Reputation: 3761

Remove entries from Map after comparing keys from a Set

I've one Map<Long, String> & one Set<Long>.

Say,

Map<Long, String> mapA
Set<Long> setB

I want to remove those entries from mapA, whose keys are not in setB.

Also I want to print log for all the entries which have been removed from mapA.

Currently I'm using iterator.

for (Iterator<Map.Entry<Long, String>> iterator = mapA.entrySet().iterator();
     iterator.hasNext(); ) {

    Map.Entry<Long, String> entry = iterator.next();
    if (!setB.contains(entry.getKey())) {
        
        LOGGER.error(entry.getKey() + " does not exist");

        // Removing from map.
        iterator.remove();
    }
}

How can I do it more concisely using Java8?

Upvotes: 0

Views: 214

Answers (1)

Youcef LAIDANI
Youcef LAIDANI

Reputation: 59970

You can use streams like this;

mapA.entrySet().removeIf(e -> {
    if(setB.contains(e.getKey())){
        return true;
    }
    LOGGER.error(e.getKey() + " does not exist");
    return false;
});

Or mush better you can call the keySet, if you don't need the values:

mapA.keySet().removeIf(k -> {
    if (setB.contains(k)) {
        return true;
    }
    LOGGER.error(k + " does not exist");
    return false;
});

Upvotes: 2

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