Lambda Built in Func Int

Question 1

Give a brief description of the functional interface Predicate{T}

Answer 1

Check a condition and returns a boolean value as result

Ex. filter() method in java.util.stream.Stream which is used to remove elements in the stream that dont match the given condition(predicate) as argument

boolean test(T t)

Question 2

Give a brief description of the functional interface Consumer{T}

Answer 2

Operation that takes an argumenet but returns nothing

ex. forEach() method in collection and in java.util.stream.Stream; this method is used for transversing all the elements in the collection or stream

void accept(T t)

Question 3

Give a brief description of the functional interface Function{T, R}

Answer 3

functions that take an argument and return a result

ex. In map() method, to transform or operate on the passed value and return a result

R apply(T t)

Question 4

Give a brief description of the functional interface Supplier{T}

Answer 4

Operation that returns a value to the caller( the returned value could be same or different values)

generate() method in java.util.stream.Stream to create an infinite stream of elements

T get()

Question 5

What is the difference between andThen() and compose() methods in Function interface?

Answer 5

The andThen() method applies the passed argumenet after calling the current Function. The compose() method calls the argument before calling the current function

Question 6

What is constructor reference?

Answer 6

Using ::new

can be used with supplier

Supplier{String} newString = String::new;
System.out.println(newString.get());

or with function

Function{String, Integer} anotherInteger = Integer::new;
System.out.println(anotherInteger.apply(“100”));

Question 7

Which of the following are valid lambda expressions?

1. () -> “”
2. x,y -> x+y
3. (Coyote y) -> return 0
4. (Camel c) -> { return}
5. Wolf w -> 39
6. () ->
7. (Animal z, m) -> a

Answer 7

1 and 4 are valid

Question 8

What does IntFunction receives as an argument?

Answer 8

takes a primitive argument but can return anything