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What is the design pattern?
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If a problem occurs over and
over again, a solution to that problem has been used effectively. That
solution is described as a pattern. The design patterns are
language-independent strategies for solving common object-oriented
design problems. When you make a design, you should know the names of
some common solutions. Learning design patterns is good for people to
communicate each other effectively. In fact, you may have been familiar
with some design patterns, you may not use well-known names to describe
them. SUN suggests GOF (Gang Of Four--four pioneer guys who wrote a
book named "Design Patterns"- Elements of Reusable Object-Oriented
Software), so we use that book as our guide to describe solutions.
Please make you be familiar with these terms and learn how other people
solve the code problems.
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Do
I have to use the design pattern?
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If you want to be a professional
Java developer, you should know at least some popular solutions to
coding problems. Such solutions have been proved efficient and
effective by the experienced developers. These solutions are described
as so-called design patterns. Learning design patterns speeds up your
experience accumulation in OOA/OOD. Once you grasped them, you would be
benefit from them for all your life and jump up yourselves to be a
master of designing and developing. Furthermore, you will be able to
use these terms to communicate with your fellows or assessors more
effectively.
Many programmers with many years experience don't know design patterns,
but as an Object-Oriented programmer, you have to know them well,
especially for new Java programmers. Actually, when you solved a coding
problem, you have used a design pattern. You may not use a popular name
to describe it or may not choose an effective way to better
intellectually control over what you built. Learning how the
experienced developers to solve the coding problems and trying to use
them in your project are a best way to earn your experience and
certification.
Remember that learning the design patterns will really change how you
design your code; not only will you be smarter but will you sound a lot
smarter, too.
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How
many design patterns?
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Many. A site says at least 250
existing patterns are used in OO world, including Spaghetti which
refers to poor coding habits. The 23 design patterns by GOF are well
known, and more are to be discovered on the way.
Note that the design patterns are not idioms or algorithms or
components.
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What
is the relationship among these patterns?
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Generally, to build a system,
you may need many patterns to fit together. Different designer may use
different patterns to solve the same problem. Usually:
- Some patterns naturally fit together
- One pattern may lead to another
- Some patterns are similar and alternative
- Patterns are discoverable and documentable
- Patterns are not methods or framework
- Patterns give you hint to solve a problem effectively
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