集合collection-map-list-set

https://blog.csdn.net/learn280668200/article/details/81284691

https://blog.csdn.net/qq_33206732/article/details/80364033

 

https://ask.csdn.net/questions/344203     map和collection

https://www.jianshu.com/p/f07b6e695ac9

 

https://blog.csdn.net/zcn596785154/article/details/79006515     Java 集合转换(数组、List、Set、Map相互转换)

 

 

set https://blog.csdn.net/weixin_38664232/article/details/99442050   集合的交集，差集    intersection（交集）和difference（差集）

SetView<Integer> intersection = Sets.intersection(集合1, 集合2);
           //求出交集
            parameter.setCityIds(intersection.copyInto(new HashSet<Integer>()))   //将intersection赋到new出来的hashset中