Question

What is the most performant way to build strings from strings, integers and floats? currently I’m doing this and it uses a lot of cpu time.

String frame = this.frameTime + ":" +
    this.player.vertices[0].x + "," +
    this.player.vertices[0].y + "," +
    this.player.activeAnimId + "," +
    (int)this.player.virtualSpeed + "," +
    this.map.getCurrentTime() + 
    (this.player.frameSound == -1 ? "" : "," + this.player.frameSound) +
    (this.player.frameDecal.equals("") ? "" : "," + this.player.frameDecal) +
    ";";

Is there a way to do this faster?

Answer 1

That should already be fast – it’ll use StringBuilder internally for concatenation. Arguably using StringBuilder explicitly could eliminate the concatenation of empty strings, but it’s not likely to make a big difference.

How often are you doing this, anyway? It must be pretty often, for it to be a bottleneck… do you really need to do it that often?

EDIT: For those who are saying “Use StringBuilder, it’ll be faster” – consider this code:

public class Test
{
    public static void main(String[] args)
    {
        int x = 10;
        int y = 20;
        int z = 30;
        String foo = x + "," + y + "," + z + ";";
        System.out.println(foo);
    }
}

Compile that, then use javap -c to see what the compiler generates…