Java 8 Supplier Functional Interface Examples

The Supplier is a class that was added in Java 8 in the java.util package with is a functional inference, that takes in no input and returns a value.

@FunctionalInterface
public interface Supplier<T> {

    /**
     * Gets a result.
     *
     * @return a result
     */
    T get();
}

Let's take a look at some examples:

import java.util.function.Supplier;

public class SupplierHelloWorld {

    public static void main(String[] args) {
        Supplier<String> supplier = () -> "Hello, world!";
        String result = supplier.get();
        System.out.println(result);
    }

}

import java.util.Random;
import java.util.function.Supplier;

public class RandomNumberSupplier {

    public static void main(String[] args) {

        Supplier<Integer> randomNumberSupplier = () -> new Random().nextInt(500);
        int randNo = randomNumberSupplier.get();
        System.out.println("Random Number: " + randNo);

    }

}

import java.time.LocalDateTime;
import java.util.function.Supplier;

public class DateTimeSupplier {

    public static void main(String[] args) {
        Supplier<LocalDateTime> dateTimeSupplier = LocalDateTime::now;
        LocalDateTime currentDateTime = dateTimeSupplier.get();
        System.out.println("Current Date and Time: " + currentDateTime);
    }

}