Java增强for循环中获取index

[b]前提测试数据：[/b]

String[] data = new String[]{"rensanning001", "rensanning002", "rensanning003"};
List dataList = Arrays.asList(data);

[b]普通的For循环：[/b]

for (int i = 0; i < dataList.size(); i++) {
  System.out.println(i + ":" + dataList.get(i));
}

[b]增强For循环（获取index需要定义额外的变量）：[/b]

int i = 0;
for (String elem : dataList) {
  System.out.println(i + ":" + elem);
  i++;
}

[b]自定义静态方法实现带index的循环：[/b]

for (Indexer elem : ExtFor1.loop(dataList)) {
  System.out.println(elem.index() + ":" + elem.value());
}

public class ExtFor1 {

	public static  Iterable> loop(final Iterable list) {
		return new Iterable>() {
			@Override
			public Iterator> iterator() {
				return new Iterator>() {
					private int counter = 0;
					private Iterator iterator = list.iterator();

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

					@Override
					public Indexer next() {
						Indexer elem = new Indexer(counter++, iterator.next());
						return elem;
					}

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

}

[b]扩展Iterable实现带index的循环：[/b]

for (Indexer elem : ExtFor2.loop(dataList)) {
  System.out.println(elem.index() + ":" + elem.value());
}

public class ExtFor2 implements Iterable> {
    private Iterator iterator;

    private ExtFor2(Iterable iter) {
        this.iterator = iter.iterator();
    }

    public static  ExtFor2 loop(Iterable iter) {
        return new ExtFor2(iter);
    }

    @Override
    public Iterator> iterator() {
		return new Iterator>() {
			private int counter = 0;

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

			@Override
			public Indexer next() {
				Indexer elem = new Indexer(counter++, iterator.next());
				return elem;
			}

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

}

[b]jquery风格的for循环：[/b]

For.each(dataList, new For.Function() {
  public void execute(int index, String elem) {
    System.out.println(index + ":" + elem);
  }
});

public class For {

	public static  void each(List list, Function function) {
		int length = list.size();
		for (int index = 0; index < length; index++) {
			function.execute(index, list.get(index)); 
		}
	}

	public static interface Function {
		public void execute(int index, T obj);
	}
}

public class Indexer {
	private final int index;
	private final T value;

	public Indexer(int index, T value) {
		this.index = index;
		this.value = value;
	}

	public int index() {
		return this.index;
	}

	public T value() {
		return this.value;
	}
}