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：

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版权声明：本文为CSDN博主「东耳佳茗」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/qq_19201215/article/details/115973047