Efficiency comparison of five methods of splicing strings in Java

preface

Recently, I wrote something. I may consider string splicing and think of several methods, but I don't know the performance, so let's test it. I won't say much. Let's take a look at the detailed introduction together.

Sample code

First: 33809

Second: 8851

Third: 6

Fourth: 12

Fifth: 7

Performance: StringBuilder > StringBuffer > stringutils join>concat>+

Then analyze from the source level

StringBuilder：

Each string splicing only expands the internal char array and produces only one final string, so this method is the most efficient

StringBuffer:

Compared with StringBuilder, it only adds an additional synchronized, so it is not much different in the case of single thread

StringUtils. join:

You can see that it is still implemented by StringBuilder, but there are more separators in each cycle, so it is a little slow, but not much. In terms of time, it is an order of magnitude

concat:

It can be seen that each connection generates a string, so the efficiency is very low

+:

Because it is an overloaded operator, the source code cannot be found, but from the result, the efficiency is the lowest

summary

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