[JAVA] List 특정 컬럼으로 그룹핑하기 Map postst = list.stream().collect(groupingBy(SalesCollectViewVo::getTmId)); System.out.println(postst.toString()); Map postsPerTypeAndAuthor = posts.stream() .collect(groupingBy(post -> new Tuple(post.getType(), post.getAuthor()))); JAVA 2021.11.17