java8 stream多次map_Java 8 lambda Stream list to Map key 重复 value合并到Collection
描述:取list集合中两个字段,且将两个字段作为key,map,利用steam流转为map集合,且满足key相同时,将value转为List集合查询到资料转自https://my.oschina.net/u/3725073/blog/1807970/ListuserList=newArrayListArrays.asList(e.getUsername()),(ListoldList,Listne