// "Replace with collect" "true" import java.util.ArrayList; import java.util.Arrays; import java.util.List; import java.util.Map; import java.util.stream.Collectors; public class Main { public void test(Map<String, String[]> map) { List<String> result = map.entrySet().stream().filter(entry -> entry.getKey().startsWith("x")).map(Map.Entry::getValue).flatMap(Arrays::stream).map(String::trim).collect(Collectors.toList()); } }