Java8 | Supplier

http://www.hitechup.com/2015/12/java-8.html

What we need to know about Supplier

• Supplier is a functional interface;

@FunctionalInterface
public interface Supplier<T>

• It takes no arguments and returns a result of type T.

T get();

• Also, through Stream’s generate method we can generate an infinite sequential stream where the supplier generates each element.

 public static<T> Stream<T> generate(Supplier<? extends T> s)

• In scenarios where we expect an output without input in any process, we can use the functional interface of Supplier <T> without having to redefine it each time.

Let’s investigate code examples :)

Use of supplier in the get method

• We used supplier get method of the Supplier interface and then it takes no argument and returns T.

Use of supplier in Stream’s generate method
Let’s say we want to generate 5 random numbers between 0 to 20

• We created supplier01 and created Random between 0 to 20.
• 6. line, we used Stream’s generate method and also gave 5 as the limit.
• 10. line, we took 2 numbers because of we used filter(Predicate<T>)
• 12. we can use it like on the line if we create a static method.

Use of supplier in LocalDate

Let’s use static LocalDateTime in different ways

Another Stream’s generate method and returns a Supplier example;

Use of supplier in orElseGet

• orElseGet (): returns the value if it exists, otherwise it calls another and returns the result of its call

public T orElseGet(Supplier<? extends T> other)

Another example;

• If a null object comes from the database when we want to get data on the database, we can call a method or return an empty object.
• We will detail the investigation about Optional in Optional blog.

Thank you for your time :)

Github: Supplier

References:

Supplier
LocalTime
StreamGenerate