使用JAVA8 filter对List多条件模糊筛选、单个参数多个值过滤、多个参数联合排序

对于从缓存中获取的list集合如果根据条件进行模糊查询呢？

条件根据indexName字段筛选需要的值

1、造数据

List<ShardsInfoDto> shardsList = new ArrayList<>();
        ShardsInfoDto shardsInfoDto = new ShardsInfoDto();
        shardsInfoDto.setIndexName("chenming20210416");
        shardsInfoDto.setDocs(3);
        shardsInfoDto.setStore(2.0);
        ShardsInfoDto shardsInfoDto1 = new ShardsInfoDto();
        shardsInfoDto1.setIndexName("asdasd");
        shardsInfoDto1.setDocs(1);
        shardsInfoDto1.setStore(4.1);
        ShardsInfoDto shardsInfoDto2 = new ShardsInfoDto();
        shardsInfoDto2.setIndexName("chenmingasdhkask");
        shardsInfoDto2.setDocs(1);
        shardsInfoDto2.setStore(5.1);
        ShardsInfoDto shardsInfoDto3 = new ShardsInfoDto();
        shardsInfoDto3.setIndexName("asdfghjkl");
        shardsInfoDto3.setDocs(4);
        shardsInfoDto3.setStore(3.1);
        ShardsInfoDto shardsInfoDto4 = new ShardsInfoDto();
        shardsInfoDto4.setIndexName("lkjhgfds");
        shardsInfoDto4.setDocs(2);
        shardsInfoDto4.setStore(1.1);
        ShardsInfoDto shardsInfoDto5 = new ShardsInfoDto();
        shardsInfoDto5.setIndexName("erghjcvghui");
        shardsInfoDto5.setDocs(2);
        shardsInfoDto5.setStore(1.2);
        ShardsInfoDto shardsInfoDto6 = new ShardsInfoDto();
        shardsList.add(shardsInfoDto);
        shardsList.add(shardsInfoDto1);
        shardsList.add(shardsInfoDto3);
        shardsList.add(shardsInfoDto4);
        shardsList.add(shardsInfoDto2);
        shardsList.add(shardsInfoDto5);
        shardsList.add(shardsInfoDto6);

2、模糊查询：

String indexName = "asd";
        shardsList = shardsList.stream().filter(ShardsInfoDto -> ShardsInfoDto.getIndexName()!=null&&ShardsInfoDto.getIndexName().indexOf(indexName) > -1).collect(Collectors.toList());
        shardsList.stream().forEach(ShardsInfoDto -> {
            System.out.println(ShardsInfoDto.getIndexName());
        });

ShardsInfoDto.getIndexName()!=null 判断防止空指针异常

输出结果：

 

 3、单个参数多个值过滤

List<String> shardStateList = new ArrayList<>();
        shardStateList.add("a");
        shardStateList.add("b");
        shardStateList.add("c");
        shardsList = shardsList.stream().filter(ShardsInfoDto -> shardStateList.contains(ShardsInfoDto.getShardStates())).collect(Collectors.toList());

4、多个参数联合排序：

String docsFlag = "asc";
        String storeFlag = "desc";
        //排序
        Comparator<ShardsInfoDto> doc = null;
        if("asc".equals(docsFlag)){
            //docs升序
            doc = Comparator.nullsFirst(Comparator.comparing(ShardsInfoDto::getDocs, Comparator.nullsFirst(Integer::compareTo)));
        }else if("desc".equals(docsFlag)){
            //docs降序
            doc = Comparator.nullsFirst(Comparator.comparing(ShardsInfoDto::getDocs, Comparator.nullsFirst(Integer::compareTo)).reversed());
        }
        Comparator<ShardsInfoDto> store = null;
        if("asc".equals(storeFlag)){
            //store升序
            store = Comparator.nullsFirst(Comparator.comparing(ShardsInfoDto::getStore, Comparator.nullsFirst(Double::compareTo)));
        }else if("desc".equals(storeFlag)){
            //store降序
            store = Comparator.nullsFirst(Comparator.comparing(ShardsInfoDto::getStore, Comparator.nullsFirst(Double::compareTo)).reversed());
        }
        // 联合排序
        Comparator<ShardsInfoDto> finalComparator = doc.thenComparing(store);
        shardsList.sort(finalComparator);
        for (ShardsInfoDto dto:shardsList) {
            System.out.println("doc:"+dto.getDocs()+",store:"+dto.getStore());
        }

Comparator.nullsFirst()防止参数为空导致空指针异常！

结果：

 

 https://blog.csdn.net/qq_19201215/article/details/115973047