package designpattern.iterator;

/**

* 具体迭代器类，给出一种具体迭代的实现方式。思考：迭代器表示的是一种迭代的行为，而聚集则是真正要被迭代的数据集合。

* 之所以要将迭代器和聚集分开，就是为了将行为与数据分开。 可类比Java中Iterator与Iterable的关系进行理解

*

* @author liu yuning

*

* @param <T>

*/

public class ConcreteIterator<T> implements Iterator<T> {

private ConcreteAggregate<T> concreteAggregate;

private int current = 0;

public ConcreteIterator(ConcreteAggregate<T> concreteAggregate) {

this.setConcreteAggregate(concreteAggregate);

}

@Override

public T first() {

return concreteAggregate.getItems(0);

}

@Override

public T next() {

current++;

if (current < concreteAggregate.count()) {

return concreteAggregate.getItems(current);

}

return null;

}

@Override

public boolean isDone() {

return current >= concreteAggregate.count() ? true : false;

}

@Override

public T currentItem() {

return concreteAggregate.getItems(current);

}

public ConcreteAggregate<T> getConcreteAggregate() {

return concreteAggregate;

}

public void setConcreteAggregate(ConcreteAggregate<T> concreteAggregate) {

this.concreteAggregate = concreteAggregate;

}

public int getCurrent() {

return current;

}

public void setCurrent(int current) {

this.current = current;

}

}