2.1 迭代器Iterator接口的使用

  1. 1).示例代码：<br />    2).迭代器的工作机制：<br />![image.png](https://cdn.nlark.com/yuque/0/2022/png/28958965/1654923654441-edd56ebb-2f6a-49ef-8363-02a768550d79.png#clientId=u162e7790-1ada-4&crop=0&crop=0&crop=1&crop=1&from=paste&height=360&id=ua12e7eaa&margin=%5Bobject%20Object%5D&name=image.png&originHeight=720&originWidth=1270&originalType=binary&ratio=1&rotation=0&showTitle=false&size=2748439&status=done&style=none&taskId=ua044f06c-d4a7-43dd-906a-034c469086f&title=&width=635)<br />

2.2 迭代器的常见问题

1).一次hasNext()，循环里面多次的next()：<br />![image.png](https://cdn.nlark.com/yuque/0/2022/png/28958965/1654923665894-398ead58-c7c1-4ecc-b323-02cd01b4cffc.png#clientId=u162e7790-1ada-4&crop=0&crop=0&crop=1&crop=1&from=paste&height=358&id=u4c348777&margin=%5Bobject%20Object%5D&name=image.png&originHeight=716&originWidth=1280&originalType=binary&ratio=1&rotation=0&showTitle=false&size=2754675&status=done&style=none&taskId=ucf99999e-f763-45fc-a146-e0b47590a89&title=&width=640)<br />            <br />    2).并发修改异常——在使用“迭代器”遍历时，通过“集合对象”去：删除、添加集合元素。<br />![image.png](https://cdn.nlark.com/yuque/0/2022/png/28958965/1654923674383-b297d86b-36d0-473d-9844-ff926c46ba24.png#clientId=u162e7790-1ada-4&crop=0&crop=0&crop=1&crop=1&from=paste&height=360&id=u2c688799&margin=%5Bobject%20Object%5D&name=image.png&originHeight=720&originWidth=1200&originalType=binary&ratio=1&rotation=0&showTitle=false&size=2596991&status=done&style=none&taskId=uf40fe227-7e1a-408f-893e-e3b341424bf&title=&width=600)            <br />            **【注意】删除集合中“倒数第二个元素”，不会出现并发修改异常！**

2.3 增强for循环

1).增强for循环，是一个语法，for循环的一种简化写法<br />        语法：for(数据类型 变量名 :   数组/集合名){<br />              }<br />        <br />    2).可以遍历数组，也可以遍历集合：<br />        A).遍历数组：<br />![image.png](https://cdn.nlark.com/yuque/0/2022/png/28958965/1654923715823-599990dd-80eb-4182-a582-5c97f7f4e86c.png#clientId=u162e7790-1ada-4&crop=0&crop=0&crop=1&crop=1&from=paste&height=100&id=u2a07baf2&margin=%5Bobject%20Object%5D&name=image.png&originHeight=199&originWidth=1280&originalType=binary&ratio=1&rotation=0&showTitle=false&size=765674&status=done&style=none&taskId=u4bf0527b-9a76-4366-ade1-96bd9b2c9e9&title=&width=640)<br />            <br />        B).遍历集合：![image.png](https://cdn.nlark.com/yuque/0/2022/png/28958965/1654923696878-95be8b0f-aac0-4d04-96b4-c5b548564daa.png#clientId=u162e7790-1ada-4&crop=0&crop=0&crop=1&crop=1&from=paste&height=296&id=uf572261c&margin=%5Bobject%20Object%5D&name=image.png&originHeight=591&originWidth=1280&originalType=binary&ratio=1&rotation=0&showTitle=false&size=2273784&status=done&style=none&taskId=ucac04371-b5b3-4ed3-88ad-906e3f1e378&title=&width=640)