Java 8 Stream 编程例子

1.利用map的key唯一

//                Mapmap=new HashMap<>();
//                for (MobileCollectQuestionSubject subject:list) {
//                    map.put(subject.getSubjectId(),subject);
//                }
//                list.clear();
//                for (String key:map.keySet()) {
//                    list.add((MobileCollectQuestionSubject) map.get(key));
//                }

2 去重使用java8

Set m=list.stream().collect(Collectors.toSet());
                list=m.stream().collect(Collectors.toList());

3 java 8

 examRoundDto.getExamObjects().stream().filter(examObjectDto -> examObjectDto.getType().equals(String.valueOf(ExaminationObjectType.EXAMINATION_PAPER_TYPE.getValue())))
                        .forEach(examObjectDto -> {
                            myExamPaperInfo.setPaperTypes(Integer.valueOf(examObjectDto.getObjectId()));
                        });

4 java8 根据数组列表的内置对象的元素进行排序

advertisementInfos list
//排序，让首页按照顺序显示
        Collections.sort(advertisementInfos, new Comparator(){

            public int compare(AdvertisementInfo o1, AdvertisementInfo o2) {

                if(o1.getAdSortNumber() > o2.getAdSortNumber()){
                    return 1;
                }
                if(o1.getAdSortNumber() == o2.getAdSortNumber()){
                    return 0;
                }
                return -1;
            }
        });