java46

1.迭代器遍历

import java.util.ArrayList;

import java.util.Collection;

import java.util.Iterator;

public class 迭代器遍历 {

@SuppressWarnings({ "rawtypes", "unchecked" })

public static void main(String[] args) {

	Collection c = new ArrayList();

	c.add("a");

	c.add("b");

	c.add("c");

//	遍历集合

	//1.数组

	Object[] o = c.toArray();

	for(int i=0;i<o.length;i++)

	{

		System.out.println(o[i]);

	}

	System.out.println("-------------------");

	//2.迭代器遍历

	Iterator it = c.iterator();

	Object obj = it.next();

	System.out.println(obj);

	Object obj2 = it.next();

	System.out.println(obj2);

	//判断集合中是否还有元素

	boolean res = it.hasNext();

	System.out.println(res);

	Object obj3 = it.next();

	System.out.println(obj3);

	Object obj4 = it.next();

	System.out.println(obj4);//没有元素了，会报错

}

}

【a

b

c

-------------------

a

b

true

c

Exception in thread "main" java.util.NoSuchElementException

	at java.util.ArrayList$Itr.next(ArrayList.java:862)

	at _07集合.迭代器遍历.main(迭代器遍历.java:34)】

        Iterator it = c.iterator();

	while(it.hasNext()) {

		System.out.println(it.next());

	}

【a

b

c】