Syed Sayem blog

Fluent Interface

Fluent Interface example using Java generics

public class Demo {
@Test
public void genericTest() {

Cake<String> cake = new Cake<String>()
.prepare()
.addFlour()
.addSugar()
.addSecretIngredient("Yogurt")
.mix()
.bake();

Pizza<String> pizza = new Pizza<String>()
.prepare()
.addSauce()
.addCheese()
.addTopping("Bacon")
.addSecretIngredient("Arugula")
.addTopping("Clams")
.bake();

cake.eat();
pizza.eat();
}
}
@SuppressWarnings("unchecked")
@FunctionalInterface
public interface Factory<E extends Factory<E>> {

E bake();

default E prepare() {
System.out.println("preparing the kitchen");
return (E) this;
}

default E eat() {
String string = new StringBuilder()
.append("Mmm, this ").append(this.getClass().getSimpleName())
.append(" is so tasty!")
.toString();

System.out.println(string);
return (E) this;
}
}
public abstract class Ingredient<E extends Ingredient<E, T>, T> implements Factory<E> {

@SuppressWarnings("unchecked")
public E addSecretIngredient(T ingredient) {
System.out.println("adding some " + ingredient);
return (E) this;
}
}
public class Cake<T> extends Ingredient<Cake<T>, T> {

public Cake<T> addSugar() {
System.out.println("adding sugar");
return this;
}

public Cake<T> addFlour() {
System.out.println("adding flour");
return this;
}

public Cake<T> mix() {
System.out.println("mixing");
return this;
}

public Cake<T> bake() {
System.out.println("baking at 325 degrees");
return this;
}
}
public class Pizza<T> extends Ingredient<Pizza<T>, T> {

public Pizza<T> addCheese() {
System.out.println("adding cheese");
return this;
}

public Pizza<T> addSauce() {
System.out.println("adding sauce");
return this;
}

public Pizza<T> addTopping(T topping) {
System.out.println("putting some " + topping + " on top");
return this;
}

public Pizza<T> bake() {
System.out.println("baking at 450 degrees");
return this;
}
}
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