应用场景:过滤空的值,并重复的值覆盖。
List<User> userList=new Arraylist<User>():
User user1=new User();
user1.setName("userName1");
user1.setAge(18);
User user2=new User();
user2.setName("userName2");
user2.setAge(18);
User user3=new User();
user3.setName("userName3");
user3.setAge(null);//空值
userList.add(user1);
userList.add(user2);
userList.add(user3);
Map<String, Integer> nameMap =userList.stream()
.filter(ss->ss.getAge()!=null)//过滤掉空的数据
.collect( Collectors.toMap(User:: getName,
User:: getAge,
(value1, value2 )-> value2));
参考文档:https://mkyong.com/java8/java-8-streams-filter-examples/