Advanced Object-Oriented Programming in Kotlin
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The Interface Segregation Principle states that code shouldn’t be forced to have methods it doesn’t need. Whenever a class implements an interface, it has to implement all its methods. What do you do when a new class appears to need some of the behaviors defined in an interface but not all? In this demo, you’ll learn how to solve this problem in your e-commerce app.
Parent account viewing products...
Product added to the cart (Parent): Laptop
Parent account viewing cart...
Kids account viewing products...
Product added to the cart (Kids): Laptop
Kids account viewing cart...
interface ProductsViewable {
fun viewProducts()
}
interface CartViewable {
fun viewCart()
}
interface CartAddable {
fun addToCart(product: Product)
}
class KidsAccount : ProductsViewable, CartViewable, CartAddable {
override fun viewProducts() {
println("Kids account viewing products...")
}
override fun addToCart(product: Product) {
println("Product added to the cart (Kids): ${product.name}")
}
override fun viewCart() {
println("Kids account viewing cart...")
}
}
interface PaymentSettingsManageable {
fun managePaymentSettings()
}
class ParentAccount : ProductsViewable, CartViewable, CartAddable, PaymentSettingsManageable {
override fun viewProducts() {
println("Parent account viewing products...")
}
override fun addToCart(product: Product) {
println("Product added to the cart (Parent): ${product.name}")
}
override fun viewCart() {
println("Parent account viewing cart...")
}
override fun managePaymentSettings() {
println("Parent account managePaymentSettings...")
}
}
// TODO: Uncomment manage payment settings behavior
parentAccount.managePaymentSettings()
Parent account viewing products...
Product added to the cart (Parent): Laptop
Parent account viewing cart...
Parent account managePaymentSettings...
Kids account viewing products...
Product added to the cart (Kids): Laptop
Kids account viewing cart...