Sorry? Why? To quote Sun ...

"In the java  programming language, you can use + to concatenate Strings
together"

and goes on to say "... behind the scenes the compiler uses StringBuffers to
implement concatenation ..."

Source
java.sun.com/.../stringsAndJavac.html

Why would you use long-hand coding like your example when the compiler is
quite capable of handling the much friendlier concatenation operator?

Quoting further from Sun, their example ...

String cat = "cat";
System.out.println("con" + cat + "enation");

apparently compiles to

String cat = "cat";
System.out.println(new StringBuffer().append("con").
append(cat).append("enation").toString());

which would probably be more efficient than the multiple statement way you
have described.

In an overwhelming proportion of cases, the actual efficiency of code is
immaterial anyway, and the readability/maintainability of the code is much
more important.