![](https://img-blog.csdnimg.cn/2021072221094879.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzU4NTI1OTQ0,size_16,color_FFFFFF,t_70)
1.UML
![](https://img-blog.csdnimg.cn/20210722222537612.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzU4NTI1OTQ0,size_16,color_FFFFFF,t_70)
二,集合的基本特点
list集合的特点(增删改查 有序 可重复)
![](https://img-blog.csdnimg.cn/20210723111219617.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzYwMzkwOTg1,size_16,color_FFFFFF,t_70)
三,List集合的三种遍历方式 (for,foreath,iterator)
![](https://img-blog.csdnimg.cn/20210723111843364.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzYwMzkwOTg1,size_16,color_FFFFFF,t_70)
四,ArrayList,LinkedList 的比较与分析
比较:
(1).ArrayList 数组 增加,删除慢 修改查询快
(2).LinkedList 链表 增加,删除快 修改查询慢
![](https://img-blog.csdnimg.cn/20210723112157774.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzYwMzkwOTg1,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/2021072311220530.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzYwMzkwOTg1,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20210723112400461.png)
五,增长因子论证
特点:
1,List集合底层是素组结构
2,它是“可变数组”,一旦超越默认数组大小,就会自动扩容
3,扩容的增长因子为0.5(扩容大小=数组的大小*0.5+原来的大小)
![](https://img-blog.csdnimg.cn/20210723112714388.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzYwMzkwOTg1,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20210723112728375.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzYwMzkwOTg1,size_16,color_FFFFFF,t_70)
六,集合框架ArrayList中的重复元素去重复及其底层原理
(1) list集合去重与去重对象的equals的方法有关
![](https://img-blog.csdnimg.cn/20210723112931376.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzYwMzkwOTg1,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20210723113010284.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzYwMzkwOTg1,size_16,color_FFFFFF,t_70)