031_自己对ArrayList中Iterator的实现

import java.util.ArrayList;
import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * 自己实现ArrayList中Iterator的实现类
 */
public class MyArrayListIterator extends ArrayList<Object> {
	private static final long serialVersionUID = 1L;

	/**
	 * 重写ArrayList的迭代方法
	 */
	@Override
	public Iterator<Object> iterator() {
		return new MyIterator();
	}

	/**
	 * 迭代类的实现
	 */
	private class MyIterator implements Iterator<Object>{
		int cursor;       
        int lastRet = -1;
        
        /**
         * 是否还有下一个元素
         */
		@Override
		public boolean hasNext() {
			return cursor != MyArrayListIterator.this.size();
		}
		
		/**
		 * 返回下一个元数
		 */
		@Override
		public Object next() {
			if(cursor >= MyArrayListIterator.this.size()) {
				throw new NoSuchElementException();
			}
			
			return MyArrayListIterator.this.get(lastRet = cursor++);
		}
		
		/**
		 * 删除当前元素
		 */
		public void remove() {
			if (lastRet < 0) {
                throw new IllegalStateException();
			}
		
			MyArrayListIterator.this.remove(lastRet);
			
			cursor = lastRet;
			lastRet = -1;
		}
		
	}
}