When is stringbuilder more efficient

Replace more efficient than String. If you have to use String. Replace to replace test 50 times, you essentially have to create a new string 50 times. Does StringBuilder.

Replace do I am currently working my way through the Learn you a Haskell book online, and have come to a chapter where the author is explaining that some list I was looking at the String Javadoc when I noticed this bit about String concatenation: The Java language provides special support for the String Concatenation unsafe in C , need to use StringBuilder?

My question is this: Is string concatenation in C safe? If string concatenation leads to unexpected errors, and replacing that string concatenation by using We mostly tend to following the above best practice. You get another result if you exclude the creation of a new object from the loop. It appears you missed the point of the first test. As such, the perf difference makes sense as with that situation, for small concat operations, stringbuilder would prove to be slower than just regular concat or interpolation.

This is a good point to consider. Therefore, the issue of using some static or non static StringBuilder depending on the implementation I believe is not a valid point for this particular test. For this reason I believe this benchmark is done incorrectly, but can be easily modified to be done correctly. By correctly, I mean a fair benchmark without unfair variables stacking odds in the favour of one or more methods over one or more other methods.

In this case, the overhead of StringBuilder object instantiation is the unfair variable causing odds to be stacked in the favour of other methods. Append as needed, without adding in the overhead of instantiating it while the stopwatch is running.

Please do consider adjusting the code in this blog entry and rerunning your benchmarks. I have to disagree. The reason is that in code you will almost always create a new instance OR do concatenation. So you have to compare between these 2 scenarios. As for Benchmark 3 — the point is to compare between the same instance and a new instance each time.

The results are interesting no? It even as fast as regular concatenation when building a string consisting of merely 2 concatenations, WITH the overhead of clear!

And with each additional concatenation the StringBuilder has to do, the performance of StringBuilder vs regular concatenation becomes even more pronounced. Overall, Benchmark3 for me really shows the most important truths.

In benchmark 1 string. Concat is 84ms, so as fast as regular concatenation. In benchmark 2, with a operations string. Concat is as fast as regular concatenation.

So much slower than StringBuilder. In fact, the compiler transforms these concatenations to string. Also, an interesting thought experiment is whether ExecuteA in your second and third benchmarks is being optimised by the compiler such that there are no actual concatenations. So in the first benchmark, when given a capacity, the StringBuilder becomes faster up to ms. To solve this problem, the StringBuilder class is used. It works like a mutable String object.

The append method helps to avoid all the copying required in string concatenation. However, Java does this string concatenation using StringBuilder by default for the simple cases.. From the Java specifications :. To increase the performance of repeated string concatenation, a Java compiler may use the StringBuffer class or a similar technique to reduce the number of intermediate String objects that are created by evaluation of an expression.

The above code will produce the following bytecode:. As you can see in the bytecode, StringBuilder is used. So we don't need to use StringBuilder anymore in Java. However, This is true for the simple cases. If you need to concatenate inside the loop, it is always suggested to use StringBuilder.

Creating and initializing a new object is more expensive than appending a character to an buffer, so that is why string builder is faster, as a general rule, than string concatenation. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 6 years, 2 months ago. Active 6 years, 2 months ago. Viewed 3k times.

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