List<Integer> list = Arrays.asList(10, 20, 30, 10);

//通过reduce方法得到一个Optional类
int a =  list.stream().reduce(Integer::sum).orElse(get("a"));
int b =  list.stream().reduce(Integer::sum).orElseGet(() -> get("b"));
System.out.println("a  "+a);
System.out.println("b  "+b);
System.out.println("hello world");

orElseThrow

//        MyDetailDTO model= Optional.ofNullable(feignUserServiceClient.getUserID(loginUserId)).map((x)->{
//            return s;
//        }).orElseThrow(()->new RuntimeException("用户不存在"));

ifPresent

 Optional.ofNullable(relCDLSuccessTempates.getTemplate()).ifPresent(template -> {
//            cdlSuccessTemplateDetailDTO.setTemplateId(template.getId());
//            cdlSuccessTemplateDetailDTO.setTitle(template.getTitle());
//            cdlSuccessTemplateDetailDTO.setDescription(template.getDescription());
//            cdlSuccessTemplateDetailDTO.setKeywords(template.getKeywords());
//        });

distinct

 List<Integer>  result=  list.stream().distinct().collect(Collectors.toList());

averagingInt

int integer=  list.stream().collect(Collectors.averagingInt());

Optional< String > fullName = Optional.ofNullable( null );
System.out.println( "Full Name is set? " + fullName.isPresent() );
System.out.println( "Full Name: " + fullName.orElseGet( () -> "[none]" ) );
System.out.println( fullName.map( s -> "Hey " + s + "!" ).orElse( "Hey Stranger!" ) );

 final long totalPointsOfOpenTasks = list
//                .stream()
//                //.filter( task -> task.getStatus() == Status.OPEN )
//                .mapToInt(x->x)
//                .sum();

list.stream().collect(Collectors.groupingBy((x)->x));


Map&groupingBy

  Map<Integer, MyDetailDTO> collect = result.stream().collect(Collectors.toMap(MyDetailDTO::getTeamsNumber, u -> u));
  Map<Integer,List<MyDetailDTO>> map = result.stream().collect(Collectors.groupingBy(MyDetailDTO::getTeamsNumber));

parallelStream
long begin = System.currentTimeMillis();

//        List<String> strings = Arrays.asList("abc", "", "bc", "efg", "abcd", "", "jkl");
//        // 获取空字符串的数量
//        int count = (int) strings.parallelStream().filter(string -> string.isEmpty()).count();
//        System.out.println("schedulerTaskCityMaster耗时:" + (System.currentTimeMillis() - begin));

joining

String mergedString = list.stream().collect(Collectors.joining(", "));

comparing&thenComparing

 result.sort(Comparator.comparing(MyDetailDTO::getStraightPushNumber)
//                .thenComparing(MyDetailDTO::getTeamsNumber)
//                .thenComparing(MyDetailDTO::getTeamsNumber));