Java 的 Scanner 对比 String.split() 对比 StringTokenizer；我应该使用哪个? [英] Java's Scanner vs String.split() vs StringTokenizer; which should I use?

问题描述

我目前正在使用 split() 来扫描一个文件，其中每行都有许多由 '~' 分隔的字符串.我在某处读到 Scanner 可以在长文件上做得更好，在性能方面，所以我想检查一下.

我的问题是:我是否必须创建两个 Scanner 实例?也就是说，一个读取一行，另一个基于该行获取分隔符的标记?如果我必须这样做，我怀疑我是否会从使用它中获得任何好处.也许我在这里遗漏了什么?

解决方案

在单线程模型中围绕这些进行了一些度量，这是我得到的结果.

<前>~~~~~~~~~~~~~~~~~~时间指标~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 分词器 |String.Split() |while+SubString |扫描仪 |ScannerWithCompiledPattern ~~ 4.0 毫秒 |5.1 毫秒 |1.2 毫秒 |0.5 毫秒 |0.1 毫秒 ~~ 4.4 毫秒 |4.8 毫秒 |1.1 毫秒 |0.1 毫秒 |0.1 毫秒 ~~ 3.5 毫秒 |4.7 毫秒 |1.2 毫秒 |0.1 毫秒 |0.1 毫秒 ~~ 3.5 毫秒 |4.7 毫秒 |1.1 毫秒 |0.1 毫秒 |0.1 毫秒 ~~ 3.5 毫秒 |4.7 毫秒 |1.1 毫秒 |0.1 毫秒 |0.1 毫秒 ~____________________________________________________________________________________________________________

结果是 Scanner 提供了最好的性能，现在同样需要在多线程模式下进行评估！我的一位前辈说 Tokenizer 会导致 CPU 峰值，而 String.split 不会.

I am currently using split() to scan through a file where each line has number of strings delimited by '~'. I read somewhere that Scanner could do a better job with a long file, performance-wise, so I thought about checking it out.

My question is: Would I have to create two instances of Scanner? That is, one to read a line and another one based on the line to get tokens for a delimiter? If I have to do so, I doubt if I would get any advantage from using it. Maybe I am missing something here?

解决方案

Did some metrics around these in a single threaded model and here are the results I got.

~~~~~~~~~~~~~~~~~~Time Metrics~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ Tokenizer  |   String.Split()   |    while+SubString  |    Scanner    |    ScannerWithCompiledPattern    ~
~   4.0 ms   |      5.1 ms        |        1.2 ms       |     0.5 ms    |                0.1 ms            ~
~   4.4 ms   |      4.8 ms        |        1.1 ms       |     0.1 ms    |                0.1 ms            ~
~   3.5 ms   |      4.7 ms        |        1.2 ms       |     0.1 ms    |                0.1 ms            ~
~   3.5 ms   |      4.7 ms        |        1.1 ms       |     0.1 ms    |                0.1 ms            ~
~   3.5 ms   |      4.7 ms        |        1.1 ms       |     0.1 ms    |                0.1 ms            ~
____________________________________________________________________________________________________________

The out come is that Scanner gives the best performance, Now the same needs to be evaluated on a multithreaded mode ! One of my senior's say that the Tokenizer gives a CPU spike and String.split does not.

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