15.1_Working with Built‐in Functional Interfaces

Question 1

📝️ What are the most Common functional interfaces?

Answer 1

T - Supplier - get
void - Consumer | BiConsumer - accept
R - Function | BiFunction | UnaryOperator | BinaryOperator - apply
boolean - Predicate | BiPredicate - test

Question 2

📝️ What is a Supplier?

Answer 2

A Supplier is used when you want to generate or supply values without taking any input.
🤓️ A Supplier is often used when constructing new objects.

🤯️⚠️📣️ Supplier suppLd = LocalDate::now;
🤯️⚠️📣️ Supplier suppSb = StringBuilder::new;
🤯️⚠️📣️ Supplier> suppAl = ArrayList::new;

Question 3

📝️ What is a Cosumer?

Answer 3

🤓️ You use a Consumer when you want to do something with a parameter but not return anything.
🤓️ BiConsumer does the same thing except that it takes two parameters.

Question 4

📝️ What is a Predicate?

Answer 4

🤓️ Predicate is often used when filtering or matching.

🤓️ A BiPredicate is just like a Predicate except that it takes two parameters instead of one.

Question 5

📝️ What is a Function?

Answer 5

🤓️ A Function is responsible for turning one parameter into a value of a potentially different type and returning it. 🤓️ Similarly, a BiFunction is responsible for turning two parameters into a value and returning it.

Question 6

📝️ What are UnaryOperator and BinaryOperator?

Answer 6

UnaryOperator and BinaryOperator, are a special case of a Function.

• > A UnaryOperator transforms its value into one of the same type. (e.g: Incrementing by one)
• > A BinaryOperator merges two values into one of the same type. (e.g: Adding two numbers)