Replace StringBuffer instances with StringBuilder

[Miguel Ángel Artaso Landa]

The class StringBuilder was introduced in Java 1.5 and according to Java API documentation available in the url http://docs.oracle.com/javase/7/docs/api/java/lang/StringBuilder.html "This class is designed for use as a drop-in replacement for StringBuffer in places where the string buffer was being used by a single thread (as is generally the case). Where possible, it is recommended that this class be used in preference to StringBuffer as it will be faster under most implementations." Hence, we should be using StringBuilder instead of StringBuffer, shouldn't we?