Chapter 8: Lambda and Functional Interfaces

Question 1

Supplier<T> is a functional interface in Java 17.</T>

Answer 1

True

Question 2

The return type of the get() method in Supplier<T> is always void.</T>

Answer 2

False – The return type is T, representing a value of any type.

Question 3

The get() method in Supplier<T> requires exactly one parameter.</T>

Answer 3

False – The get() method takes zero parameters.

Question 4

Supplier<T> can be used to supply values on demand.</T>

Answer 4

True

Question 5

Supplier<T> was introduced in Java 17.</T>

Answer 5

False – Supplier<T> was introduced in Java 8.</T>

Question 6

Can lambda parameters in Java be declared without explicitly stating their types?

Answer 6

Yes. If the compiler can infer the types from the context, you can omit them in the lambda expression.

Question 7

Is it allowed to mix inferred and explicit types in a single lambda expression in Java?

Answer 7

No. All parameters must either have their types explicitly declared or all must be inferred — mixing is not allowed.

Question 8

What enables Java to allow type-less parameter declarations in lambdas?

Answer 8

Java’s type inference mechanism determines parameter types from the target functional interface’s method signature.