A case where you can't fast-enumerate an Iterable, 1/3

FastEnumGotcha1.java

// This works perfectly as a Java program, but produces wrong output when
// translated into Objective-C. Can you spot why?

import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

public class FastEnumGotcha {
  static class Wrapper<T> {
    T value;

    void set(T value) {
      this.value = value;
    }

    T get() {
      return value;
    }
  }

  static class Data implements Iterable<Wrapper<String>> {
    List<String> strings;
    Data(String[] strings) {
      this.strings = Arrays.asList(strings);
    }

    @Override
    public Iterator<Wrapper<String>> iterator() {
      return new Iterator<Wrapper<String>>() {
        Wrapper<String> w = new Wrapper<>();
        Iterator<String> it = strings.iterator();

        @Override
        public boolean hasNext() {
          return it.hasNext();
        }

        @Override
        public void remove() {
          throw new UnsupportedOperationException();
        }

        @Override
        public Wrapper<String> next() {
          w.set(it.next());
          return w;
        }
      };
    }
  }

  public static void main(String args[]) {
    String x[] = {
      "alpha", "bravo", "charlie", "delta", "echo", "foxtrot", "golf", "hotel", "india",
      "juliet", "kilo", "lima", "mike", "november", "oscar", "papa", "quebec", "romeo",
      "sierra", "tango", "uniform", "victor", "whiskey", "x-ray", "yankee", "zulu"
    };

    Data data = new Data(x);
    for (Wrapper<String> w : data) {
      System.out.printf("%s ", w.get());
    }
    System.out.println();
  }
}