Pattern Recognition, Classification

• You can write perfect Java programs without using patterns, but much of your time will be needlessly wasted.  Mastering patterns is required for mastering Java, yet many programmers don't do it!
• Patterns rely heavily on interfaces, polymorphism, and abstraction.  A good pattern programmer will use these components. 
  
• Using patterns helps you make forward-thinking, re-usable code.
• PatternDepot.com states three stages in learing patterns:
• Acceptance - realize that patterns are important.
• Recognition - realize that you need to study patterns to know how to use them.
• Internalization - reach the 'aha' factor where thinking of programming with patterns is automatic.
• Unfortunately, patterns are hard to teach and learn in a classroom.  But they are very important.  After hours and years of programming, patterns become invaluable.  The moral?  This is one thing we'll talk about now, but you might find that you actually learn it months or years after you have forgotten my name!
• The folks at www.patterndepot.com have divided 23 of the most common patterns into three categories:
• Creational Patterns are in the business of creating objects.  The Factory Pattern would fall under this category.
• Structural Patterns compose objects into more complex structures.
• Behavioral Patterns define communication among objects.  The command pattern, one of my favorite, falls in this category.
• Many of the 23 patterns are complex and best suited for programmers who have years of experience.  As a matter of fact, most patterns are not designed ahead of time, but rather discovered after review of many previously written programs.  We won't cover the more complex patterns.  But there are a number of patterns that are simple and fundamental - some you may have already used with our without knowing it!