Use Supplier Interface in Lambda Expression in Java

A Supplier<T> interface is a pre-defined interface that represents the supplier of results. It is instantiated using lambda expression or method reference or default constructor. The functional method of a Supplier<T> interface is the get() method. This interface belongs to java.util.function package.

Syntax

@FunctionalInterface
public interface Supplier<T>

In the below program, we can use the Supplier interface in a lambda expression. The get() method only returns a value and doesn't accept any argument, so a lambda expression having an empty argument part.

Example

import java.util.*;
import java.util.function.*;

public class SupplierTest {
   public static void main(String args[]) {
      Supplier<String> supplier1 = () -> "TutorialsPoint";   // lambda expression
      System.out.println(supplier1.get());

      Supplier<Integer> supplier2 = () -> 7;    // lambda expression
      System.out.println(supplier2.get());

      Person p = new Person("Raja");
      Person p1 = get(() -> p);
      Person p2 = get(() -> p);
      System.out.println(p1.equals(p2));
   }
   public static Person get(Supplier<Person> supplier) {
      return supplier.get();
   }
}

// Person class
class Person {
   public Person(String name) {
      System.out.println(name);
   }
}

Output

TutorialsPoint
7
Raja
true