Case Insensitive filtering using Google Guava

Question

Current I am using following piece of code to create a filter, in a map to match and give a filtered list of resultset.

final Map filteredMap = Maps.filterKeys(mymap, Predicates.containsPattern("^Xyz"));

However Guava Predicates.containsPattern does case-sensitive matching.

How should I use containsPattern for doing case-Insensitive matching.

Answer 1

Use

Predicates.contains(Pattern.compile("^Xyz", Pattern.CASE_INSENSITIVE))

as predicate instead. See core Java Pattern and Predicates.contains.

EDIT (after OP's comment): yes, you can write:

Predicates.containsPattern("(?i)^Xyz"))

(see Pattern's documentation: Case-insensitive matching can also be enabled via the embedded flag expression (?i).) but it's IMO less self-explaining, plus compiled Pattern from first example can be cached to some private static final constant when used in a loop, which can improve performance.