浅谈java集合

比眉伴天荒 2022-05-20 08:06 207阅读 0赞

java集合框架:

简书地址：

[https://www.jianshu.com/p/589d58033841][https_www.jianshu.com_p_589d58033841]

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HashMap底层实现：

[https://www.jianshu.com/p/3bf097f4cf0a][https_www.jianshu.com_p_3bf097f4cf0a]

HashMap扩容：

[https://blog.csdn.net/witsmakemen/article/details/78820410][https_blog.csdn.net_witsmakemen_article_details_78820410]

[https://blog.csdn.net/LovePluto/article/details/79755496][https_blog.csdn.net_LovePluto_article_details_79755496]

HashMap之Hash碰撞：

[https://blog.csdn.net/luo\_da/article/details/77507315][https_blog.csdn.net_luo_da_article_details_77507315]

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ArrayList,LinkedList,Vector的区别

ArrayList采用数组实现, LinkedList采用链表实现;

ArrayList查改快,增删慢,LinkedList反之;

ArrayList与Vector,ArrayList线程不安全,Vector线程安全

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HashMap,LinkedHashMap,TreeMap的区别

HashMap 最多只允许一条记录的键为Null;允许多条记录的值为 Null; HashMap线程不安全  
HashTable 对放入的key与value都不能为空,所有方法都用synchronized修饰，线程安全

ConcurrentHashMap 与 HashTable的区别是:

Hashtable是用synchronized针对整张Hash表(十分浪费资源)，

而ConcurrentHashMap是（jdk7采用分段锁）— (jdk8采用CAS算法)

LinkedHashMap内部维持了一个双向链表,可以保持顺序(放入顺序与输出顺序相同)线程不安全  
  
TreeMap（默认是升序排序,也可以指定排序）

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集合的底层实现  
HashMap/ConcurrentHashMap: 数组+链表+红黑树(链表长度大于8时,转换为红黑树)

LinkedHashMap相对于HashMap来说是增加了双向链表（双向链表用来控制顺序）

[https_www.jianshu.com_p_589d58033841]: https://www.jianshu.com/p/589d58033841
[https_www.jianshu.com_p_3bf097f4cf0a]: https://www.jianshu.com/p/3bf097f4cf0a
[https_blog.csdn.net_witsmakemen_article_details_78820410]: https://blog.csdn.net/witsmakemen/article/details/78820410
[https_blog.csdn.net_LovePluto_article_details_79755496]: https://blog.csdn.net/LovePluto/article/details/79755496
[https_blog.csdn.net_luo_da_article_details_77507315]: https://blog.csdn.net/luo_da/article/details/77507315