<dependency> <groupId>org.eclipse.collections</groupId> <artifactId>eclipse-collections</artifactId> <version>10.4.0</version> </dependency> MutableSet<Integer> set = Sets.mutable.with(1, 2, 3, 4, 5); MutableSet<Integer> filteredSet = set.select(each -> each % 2 == 0); MutableSet<Integer> set = Sets.mutable.with(1, 2, 3, 4, 5); MutableSet<String> transformedSet = set.collect(String::valueOf); MutableList<Integer> list = Lists.mutable.with(1, 2, 3, 4, 5); int sum = list.sumOfInt(Integer::intValue);