OnJava8-Examples/collections/GenericsAndUpcasting.java

// collections/GenericsAndUpcasting.java
// (c)2020 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
import java.util.*;

class GrannySmith extends Apple {}
class Gala extends Apple {}
class Fuji extends Apple {}
class Braeburn extends Apple {}

public class GenericsAndUpcasting {
  public static void main(String[] args) {
    ArrayList<Apple> apples = new ArrayList<>();
    apples.add(new GrannySmith());
    apples.add(new Gala());
    apples.add(new Fuji());
    apples.add(new Braeburn());
    for(Apple apple : apples)
      System.out.println(apple);
  }
}
/* Output:
GrannySmith@15db9742
Gala@6d06d69c
Fuji@7852e922
Braeburn@4e25154f
*/