@Test public void fun1() throws Exception { UserVo user1 = new UserVo(); user1.setUsername("zhangsan"); UserVo user2 = new UserVo(); user2.setUsername("lisi"); ArrayList<UserVo> list = new ArrayList<UserVo>(); list.add(user1); list.add(user2); List<UserVo> newList = list.stream().map(u -> { String username = u.getUsername(); u.setUsername(username + "111"); return u; }).collect(Collectors.toList()); System.out.println(newList); }