Efficient way to convert long to String in Java

Question

I've been using

long a = 123456789;
String b = a+"";

to convert a long value (or int) to String, or in this perspective, treat it as String. My question is, is it ok to do this? Are there any negative impact?

And is there any difference in using String.valueOf() vs Long.toString()?

Thanks

Answer 1

It is ok to do this as recent JVM will likely reduce it to:

String b = String.valueOf(a);

As for negatives, it is not good Java coding style as there is ambiguity. If a was null, would b = "null"? or will an NPE be thrown? You know the answer with experience, but this should be obvious to all readers of your code.

Answer 2

First, your code doesn't compile - you have to append an L after the literal:

Long a = 123456789L;

String.valueOf() and Long.toString() methods both have a primitive long as a parameter, but since a is an wrapper (Long), you can just use the Object#toString() method:

String b = a.toString();

If a, however, is a primitive (long), both String.valueOf() and Long.toString() will do the same, so it's a matter of preference which one to use.