分类：多字段

2020
10-10

Java8 stream 中利用 groupingBy 进行多字段分组求和案例

Java8的groupingBy实现集合的分组，类似Mysql的groupby分组功能，注意得到的是一个map对集合按照单个属性分组、分组计数、排序List<String>items=Arrays.asList("apple","apple","banana","apple","orange","banana","papaya");//分组Map<String,List<String>>result1=items.stream().collect(Collectors.groupingBy(Function.identity()));//{papaya=[papaya],orange=[orange],banan... 继续阅读 >

2020
10-10

java8 集合 多字段 分组 统计个数代码

1.user实体packagecom.demo.dto;publicclassUser{privateIntegerid;privateStringuserName;privateStringpassword;privateIntegerage;privatelongc;publicUser(){super();//TODOAuto-generatedconstructorstub}publicUser(Integerid,StringuserName,Stringpassword,Integerage){super();this.id=id;this.userName=userName;this.password=password... 继续阅读 >