Pattern · Core

Strategy

Define a family of interchangeable algorithms, put each in its own class, and let the client swap them at runtime — instead of a big if/else picking behaviour.

Asked atAmazonStripeUber

step 1 / 7

1/2if/else picks the algorithm

Checkout

+ pay(amt)

if/else picks the algorithm

 1class Checkout {
 2    void pay(int amt){
 3        if      (method == CARD)   { ... }
 4        else if (method == PAYPAL) { ... }   // add one → edit here
 5    }
 6}

State

pay()if/else chain

✦

One Checkout class, one pay() method — and inside it a chain of if/else, each branch a whole payment algorithm. Card here, PayPal there, crypto next.