6.2 Introducing Functional Interfaces

Question 1

📝️ What friend can help us remember what is a functional interface?

Answer 1

Our dear friend SAM, because a Functional Interface contains a Single Abstract Method aka (SAM)

Question 2

📝️ What annotation does Java provide to confirm an Interface is Functional?

Answer 2

@FunctionalInterface

Question 3

📝️ What package is specifically designed to contain only functional interfaces that are reused in the rest of the library?

Answer 3

java.util.function

Question 4

📝️ What are the 4 fundamental predefined Functional Interfaces?

Answer 4

Predicate -> boolean test(T t)
Function -> R apply(T t)
Consumer -> void accept(T t)
Supplier -> T get()

Question 5

📝️ What feature does java.lang.Comparable provides?

Answer 5

single-sorting sequence
-> In other words, we can sort the collection on the basis of a 🧠️single element🧠️ such as id, name, or price. (It’s predefined Natural sort)

Question 6

📝️ Does Comparable interface affects the original class?

Answer 6

Yes, It performs a 💥️Mutable💥️ process

Question 7

📝️ What is the S.A.M of Comparable?

Answer 7

Comparable :: int compareTo​(T o);

Question 8

📝️ What features does java.util.Comparator provides?

Answer 8

multiple-sorting sequence

-> We can sort a collection on the basis of 🧠️multiple elements🧠️

Question 9

📝️ Does Comparator interface affects the original class?

Answer 9

No, , It performs an💥️Immutable💥️ process

Question 10

📝️ What is the S.A.M of Comparator?

Answer 10

Comparator :: int compare(T o1, T o2);