Quote marks when concatenating string with a single character

Question

What kind of quote marks should I choose for a single character when I concatenate it with a string?

String s1="string";

Should I use

String s2=s1+'c';

Or

String s2=s1+"c";

?

Answer 1

You can use both! Give it a try!

"Why?" you ask. The magic here is the + operator.

When + is used with strings, it automatically turns the other operand into a string! That's why it can be used with 'c' , a character literal. It can also be used with "c" because of course, "c" is a string literal.

Not only that, you can even add integers to a string:

String s2=s1+1;

Answer 2

U can use it in two diferent ways : String s2=s1+'c'; and char x = 'c'; String s2 = s1 + x; char x = 'c'; String s2 = s1 + x;

Answer 3

Both approaches are ok but if you are going into the details then perhaps

String s2=s1+'c';

will take a little less memory than the second way because char is just two bytes while String requires 8+ bytes. But I don't think that such nuances are important in most cases and also I'm not even sure that this difference will exist at all because JVM may optimize it

Answer 4

Java automatically does the conversion for you, so it doesn't really matter, but I'd personally just use a string (double quotes) just because I personally prefer to minimize the 'automatic stuff' that happens if I can prevent it.

Also, if you ever decide that 'c' should be 'csomething', then you'll have to change it into a boudle quote anyway.

But I suppose I'm just nitpicking...

Answer 5

Those are 2 different types of casting: implicit casting and explicit casting .

String s2=s1+'c';

This is a implicit casting, which means that the magic is done by the compiler (no overhead).

String s2=s1+"c";

This is a explicit casting, because "c" is converted to an object like:

Object o = "c";
String s2 = (String) o;

This means that the conversion must be checked for null-pointers, which will create an overhead.

Therefore, while both ways works, I prefer casting from character ('c') because that will create less overhead!

source: http://www.javaworld.com/article/2076555/build-ci-sdlc/java-performance-programming--part-2--the-cost-of-casting.html