Best practices/performance: mixing StringBuilder.append with String.concat

Question

I\'m trying to understand what the best practice is and why for concatenating string literals and variables for different cases. For instance, if I have code like this

Answer 1

I personally prefer the Strings.format(), simple easy to read one-line string formatter.

String b = "B value";
String d = "D value";
String fullString = String.format("A %s C %s E F", b, d);
// Output: A B value C D value E F