SupplierInterfaceExample.java

package com.kiroule.ocpupgradejava8.topic2_4;

import java.util.function.Supplier;

/**
 * @author Igor Baiborodine
 */
public class SupplierInterfaceExample {

  public static void printGreeting(Supplier<HelloWorld> supplier) {
    System.out.println(supplier.get().getGreeting());
  }

  public static void main(String... args) {

    Supplier<HelloWorld> supplier = HelloWorld::new;

    printGreeting(supplier);
    printGreeting(() -> new HelloWorld());
    printGreeting(new CustomGreetingSupplier());
  }
}

class CustomGreetingSupplier implements Supplier<HelloWorld> {

  @Override
  public HelloWorld get() {
    HelloWorld helloWorld = new HelloWorld();
    helloWorld.setGreeting("Custom Hello World!");
    return helloWorld;
  }
}

class HelloWorld {

  private String greeting = "Default Hello World!";

  public String getGreeting() {
    return greeting;
  }

  public void setGreeting(String greeting) {
    this.greeting = greeting;
  }
}