How does the Strategy Pattern work? [closed]

Let’s explain the strategy pattern the easy way:

You have a class Car() with a method run(), so you use it this way in a pseudo language:

mycar = new Car()
mycar.run()

Now, you may want to change the run() behavior on the fly, while the program is executing. For example, you might want to simulate a motor failure or the use of a “boost” button in a video game.

There are several ways to do this simulation: using conditional statements and a flag variable is one way. The strategy pattern is another: it delegates the behavior of the run() method to another class:

Class Car()
{
    this.motor = new Motor(this) 

    // passing "this" is important for the motor so it knows what it is running

    method run()
    {
        this.motor.run()
    }

    method changeMotor(motor)
    {
        this.motor = motor 
    }

}

If you want to change the car’s behavior, you can just change the motor. (Easier in a program than in real life, right? 😉 )

It’s very useful if you have a lot of complex states: you can change and maintain them much more easily.