Question

I would like to know about the relation between string literal and java performance.

for example, uses of below statements number of times makes any impact in performance.I have thousands of classes and many time we are using below statements :

1) buffer.append(",");
2) buffer.append("}");

3)String.append("10,000 times...same lines") // printing same lines in many classes
3)String.someStringMethod("same line many times") // using any String method 

Does this cause performance impact in terms of memory management etc.Do we have any cleaner way ?

Thanks

Answer 1

It is really difficult to comment on examples that make no sense. However:

• In general there are no particular efficiency concerns with Java String literals.
• In general there are no particular efficiency concerns with methods that take String literals as arguments.
• String concatenation / building can present efficiency concerns if a particular piece of code is executed often enough. However, if you need to build strings, then there is not a lot you can do about it.

There are one or two things that it is worth taking steps to avoid. The main one is this:

   String s = "";
   for (/* lots of times */) {
       // do stuff
       s += someOtherString;
   }

The problem is that this generates and then discards lots of temporary Strings. The more efficient way to do it is this:

   StringBuilder sb = new StringBuilder();
   for (/* lots of times */) {
       // do stuff
       sb.append(someOtherString);
   }
   String s = sb.toString();

However, it is probably only worth while optimizing this kind of thing if the profiler tells you that this particular bit of code is a bottleneck.