Java的Scanner vs String.split（）vs StringTokenizer;我应该用哪个？ [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（）来浏览一个文件，其中每一行都有'〜'。我读到某个地方 Scanner 可以用一个长文件做得更好，性能方面，所以我想考虑一下。

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.

我的问题是：我是否必须创建两个 Scanner 的实例？也就是说，一个读取一行而另一个基于该行来获取分隔符的标记？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一些东西？

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?

推荐答案

在单线程模型中有一些关于这些的指标，这里是我得到的结果。

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            ~
____________________________________________________________________________________________________________

出来的是Scanner提供最佳性能，现在同样需要评估多线程模式！我的一位大四学生说Tokenizer给出了CPU峰值而String.split没有。

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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