[英]How to search a subString in a big list<String> - Java
I have a big list<String>
that is about 50,000 records. 我有一个很大的list<String>
,大约有50,000条记录。 I want an effective way to search for a specific subString
in that List
and get the Strings
that contains that subString
. 我想要一种有效的方法来搜索该List
的特定subString
并获取包含该subString
的Strings
。
My code is like this so far: 到目前为止,我的代码是这样的:
List<String> result = new ArrayList<>();
if (aCondition) {
for (String file : arg) {
if (file.toLowerCase().contains(tag.toLowerCase())) {
result.add(file);
}
}
}
return result;
It depends on what you mean by effective . 这取决于您所说的有效 。
If you want to get to "minimal" CPU usage, then there isn't much you can do: you have to iterate that list; 如果要达到“最小” CPU使用率,那么您就无能为力了。 and compare all entries. 并比较所有条目。 The only obvious thing to not do: call tag.toLowerCase()
for each loop body. 唯一明显的事情不做 :调用tag.toLowerCase()
每个循环体。 Just compute that value once before entering the loop! 在进入循环之前,只需计算一次该值即可 !
If you care about getting result in less time, the answer is simple: use multiple threads, and have each thread search a "slice" of the overall list (of course, that can turn complicated quickly, as you now have to preserve order and other subtle things). 如果您想在更短的时间内获得结果,答案很简单:使用多个线程,并让每个线程搜索整个列表的“切片”(当然,这很快就会变得很复杂,因为您现在必须保留顺序和其他细微的东西)。
Finally: you might want to look into tools such ElasticSearch - as there are various products designed to exactly do that: search huge amounts of text. 最后:你可能要考虑的工具, ElasticSearch -因为我们有专门正是这样做的各种产品:搜索文本的巨额资金。
Consider to use a SQL database to hold big amounts of data. 考虑使用SQL数据库保存大量数据。
In this way you can use a simple query to get a result String containing a substring (look at example below). 这样,您可以使用简单的查询来获取包含子字符串的结果String(请参见下面的示例)。 Furthermore your memory will be free of that amount of data loaded in list. 此外,您的内存将没有列表中加载的数据量。
eg 例如
SELECT * from word_list_table WHERE word LIKE'%substring%'
If your processor has more than one core just go and use parallel streams. 如果您的处理器有多个内核,那就去使用并行流。
List<String> result = lines.parallelStream() //convert list to parallel stream
.filter(line -> file.toLowerCase().contains(tag.toLowerCase())) // check your condition
.collect(Collectors.toList()); // collect output
The above code will process your strings faster if your processor has more than one core because a parallel stream is opened. 如果您的处理器具有多个内核,因为打开了并行流,则以上代码将更快地处理您的字符串。
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