Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets

the algorithm vary independently from clients that use it.

the algorithm vary independently fromtheclients that use it.

Realworld example

Real-world example

In plain words

Wikipedia says

**Programmatic Example**

Let's first introduce the dragonslaying strategy interface and its implementations.

Let's first introduce the dragon-slaying strategy interface and its implementations.

}

And here is the mighty dragonslayer, whois able to pick his fighting strategy based on the

And here is the mighty dragonslayer, whocan pick his fighting strategy based on the

opponent.

}

Finally here's the dragonslayer in action.

Finally, here's the dragonslayer in action.

LOGGER.info("Green dragon spotted ahead!");

What's more, thenew feature Lambda Expressions in Java 8 provides another approach for the implementation:

What's more, thelambda expressions in Java 8 provides another approach for the implementation:

publicclassLambdaStrategy {

dragonSlayer.goToBattle();

Programoutput is the same as above one.

The programoutput is the same as the above one.

* 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

* 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, movetherelated conditional branches into their own Strategy class