OnJava8-Examples/generics/GenericWriting.java

// generics/GenericWriting.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
import java.util.*;

public class GenericWriting {
  static <T> void writeExact(List<T> list, T item) {
    list.add(item);
  }
  static List<Apple> apples = new ArrayList<>();
  static List<Fruit> fruit = new ArrayList<>();
  static void f1() {
    writeExact(apples, new Apple());
    writeExact(fruit, new Apple());
  }
  static <T> void
  writeWithWildcard(List<? super T> list, T item) {
    list.add(item);
  }
  static void f2() {
    writeWithWildcard(apples, new Apple());
    writeWithWildcard(fruit, new Apple());
  }
  public static void main(String[] args) { f1(); f2(); }
}