Creating subset of HashMap based on some specifications?

Question

So I have the following HashMap:

HashMap<String, List<someDataType>> map;

I want to create a new HashMap that is only composed of the k/v pairs in map that have a value (the list) whose length is less than a certain "x". The only way I know how to do this is to iterate through the HashMap and put k/v pairs into a new HashMap. Is there a more concise way to achieve what I'm looking for? Thanks.

Answer 1

Using guava:

Map<String, List<String>> newMap = 
    Maps.filterEntries(originalMap, new MyEntryPredicate(10));

where:

private static class MyEntryPredicate implements Predicate<Map.Entry<String, List<String>>> {

    // max list length, exclusive
    private int maxLength;

    private MyEntryPredicate(int maxLength) {
        this.maxLength = maxLength;
    }

    @Override
    public boolean apply(Map.Entry<String, List<String>> input) {
        return input != null && input.getValue().size() < maxLength;
    }
}