How to create a simple iterator in Java with just one method.

ClosureIterator.java

public class ClosureIterator {

	private static interface Iterator<T> {
		T next();
	}
	
	private static class Container<T> {
		private T value;

		public Container(T value) {
			setValue(value);
		}

		public T getValue() {
			return value;
		}

		public void setValue(T value) {
			this.value = value;
		}
	}
	
	private static Iterator<Integer> evenGenerator() {
		final Container<Integer> i = new Container<>(0);
		return new Iterator<Integer>() {
			@Override
			public Integer next() {
				int tmp = i.getValue();
				i.setValue(i.getValue() + 2);
				return tmp;
			}
		};
	}
	
	public static void main(String[] args) {
		Iterator<Integer> it = evenGenerator();
		System.out.println(it.next()); // 0
		System.out.println(it.next()); // 2
		System.out.println(it.next()); // 4
	}

}