A String buffer is an efficient way to build a big string by appending small elements together.
Its cross-platform implementation uses String concatenation internally, but StringBuf may be optimized for different targets.
Unlike String, an instance of StringBuf is not immutable in the sense that it can be passed as argument to functions which modify it by appending more values. However, the internal buffer cannot be modified.
Creates a new StringBuf instance.
This may involve initialization of the internal buffer.