OnJava8-Examples/generics/UnboundedWildcards2.java

// generics/UnboundedWildcards2.java
// <20>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 UnboundedWildcards2 {
  static Map map1;
  static Map<?,?> map2;
  static Map<String,?> map3;
  static void assign1(Map map) { map1 = map; }
  static void assign2(Map<?,?> map) { map2 = map; }
  static void assign3(Map<String,?> map) { map3 = map; }
  public static void main(String[] args) {
    assign1(new HashMap());
    assign2(new HashMap());
    // assign3(new HashMap()); // Warning:
    // Unchecked conversion. Found: HashMap
    // Required: Map<String,?>
    assign1(new HashMap<>());
    assign2(new HashMap<>());
    assign3(new HashMap<>());
  }
}
/* Output: (None) */