Question

I’m new in Design Patterns so I have one question about the Builder Pattern.
Today I heard that Builder Pattern is different from the class StringBuilder in Java, C#. I know that main goal of the Builder Pattern is to create complex objects in few steps…I think that this is making StringBuilder with it’s method Append…So it’s hardly for me to find the difference…

Could you tell me is there really any difference and if it is…what’s it :)?

Answer 1

It sounds like you might be confusing the class StringBuilder and the Builder Design Pattern. They are actually two very different ideas.

StringBuilder is a class in Java and .NET that allows more performant string operations: (From MSDN)

The String object is immutable. Every
time you use one of the methods in the
System.String class, you create a new
string object in memory, which
requires a new allocation of space for
that new object. In situations where
you need to perform repeated
modifications to a string, the
overhead associated with creating a
new String object can be costly. The
System.Text.StringBuilder class can be
used when you want to modify a string
without creating a new object. For
example, using the StringBuilder class
can boost performance when
concatenating many strings together in
a loop.

The Builder Pattern on the other hand is a design pattern which is a set of classes and/or interfaces meant to organize complex code:

The builder pattern is a software
design pattern. The intention is to
abstract steps of construction of
objects so that different
implementations of these steps can
construct different representations of
objects. Often, the builder pattern is
used to build products in accordance
to the composite pattern, a structural
pattern.

The Append method of StringBuilder simply adds more characters to the existing string. There are no new objects created (basic function of the builder pattern) and there is no design pattern involved. It’s a single method call to a single object instance.