Question

I’m looking for a method like:

myMap.containsKeyStartingWith("abc"); // returns true if there's a key starting with "abc" e.g. "abcd"

or

MapUtils.containsKeyStartingWith(myMap, "abc"); // same

I wondered if anyone knew of a simple way to do this

Thanks

Answer 1

This can be done with a standard SortedMap:

Map<String,V> tailMap = myMap.tailMap(prefix);
boolean result = (!tailMap.isEmpty() && tailMap.firstKey().startsWith(prefix));

Unsorted maps (e.g. HashMap) don’t intrinsically support prefix lookups, so for those you’ll have to iterate over all keys.