// generics/CaptureConversion.java
// (c)2017 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.

public class CaptureConversion {
 static <T> void f1(Holder<T> holder) {
 T t = holder.get();
 System.out.println(t.getClass().getSimpleName());
 }
 static void f2(Holder<?> holder) {
 f1(holder); // Call with captured type
 }
 @SuppressWarnings("unchecked")
 public static void main(String[] args) {
 Holder raw = new Holder<>(1);

 f1(raw);
 // warning: [unchecked] unchecked method invocation:
 // method f1 in class CaptureConversion
 // is applied to given types
 // f1(raw);
 // ^
 // required: Holder<T>
 // found: Holder
 // where T is a type-variable:
 // T extends Object declared in
 // method <T>f1(Holder<T>)
 // warning: [unchecked] unchecked conversion
 // f1(raw);
 // ^
 // required: Holder<T>
 // found: Holder
 // where T is a type-variable:
 // T extends Object declared in
 // method <T>f1(Holder<T>)
 // 2 warnings

 f2(raw); // No warnings
 Holder rawBasic = new Holder();

 rawBasic.set(new Object());
 // warning: [unchecked] unchecked call to set(T)
 // as a member of the raw type Holder
 // rawBasic.set(new Object());
 // ^
 // where T is a type-variable:
 // T extends Object declared in class Holder
 // 1 warning

 f2(rawBasic); // No warnings
 // Upcast to Holder<?>, still figures it out:
 Holder<?> wildcarded = new Holder<>(1.0);
 f2(wildcarded);
 }
}
/* Output:
Integer
Integer
Object
Double
*/