Java 8: Collection map and trim

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class StreamingList {
    public static void main(String[] args) {
        List<String> originalStrings = Arrays.asList("foo ", " bar", " baz ");

        {   // Plain-old Java Loop
            List<String> trimmedStrings = new ArrayList<String>();
            for (String s : originalStrings) {
                trimmedStrings.add(s.trim());
            }
            System.out.println(trimmedStrings);
        }
        {   // Java 7 (Anonymous function)
            List<String> trimmedStrings = CollectionUtil.map(originalStrings, new CollectionUtil.Mapper<String, String>() {
                @Override
                public String map(String item) {
                    return item.trim();
                }
            });
            System.out.println(trimmedStrings);
        }
        {   // Java 8 (Lambda function with custom interface)
            List<String> trimmedStrings = CollectionUtil.map(originalStrings, (String item) -> item.trim());
            System.out.println(trimmedStrings);
        }
        {   // Java 8 (Lambda function)
            List<String> trimmedStrings = originalStrings.stream().map(String::trim).collect(Collectors.toList());
            System.out.println(trimmedStrings);
        }
    }

    private static class CollectionUtil {
        public static interface Mapper<T, U> {
            public U map(T item);
        }
        public static <T, U> List<U> map(Iterable<T> list, Mapper<T, U> mapper) {
            List<U> result = new ArrayList<U>();
            for (T item : list) {
                result.add(mapper.map(item));
            }
            return result;
        }
    }
}