import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; public class Uncompilable { static final List stringList = Arrays.asList("doesnt", "matter"); static final String finalJoinedMappedAppendedString = "" + fakeJoin(stringList.stream().map(str -> str).collect(Collectors.toList())); private static String fakeJoin(List doesntMatter) { return "anything"; } public static void main(String[] args) { } }