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Strategy

Difficulty-Beginner Gang Of Four Java Behavioral

Also known as

Policy

Intent

Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.

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Applicability

Use the Strategy pattern when

  • many related classes differ only in their behavior. Strategies provide a way to configure a class either one of many behaviors
  • you need different variants of an algorithm. for example, you might define algorithms reflecting different space/time trade-offs. Strategies can be used when these variants are implemented as a class hierarchy of algorithms
  • an algorithm uses data that clients shouldn't know about. Use the Strategy pattern to avoid exposing complex, algorithm-specific data structures
  • a class defines many behaviors, and these appear as multiple conditional statements in its operations. Instead of many conditionals, move related conditional branches into their own Strategy class

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