generics - In Java is it possible to create a type-safe Map of classes to instances of their class?

Question

I would like to create a map that uses a class as a key to return an instance of that class. Something like:

<T> Map< Class<T>, T > instanceMap = new HashMap< Class<T>, T > ();
instanceMap.put( Boolean.class, Boolean.TRUE );
instanceMap.put( String.class, "asdf" );   
instanceMap.put( Integer.class, 11 );

Boolean b = instanceMap.get( Boolean.class );
Integer i = instanceMap.get( Integer.class );
String s  = instanceMap.get( String.class  );

Is this possible? I have a feeling that no it is not because I cannot indicate that T is meant to be a generic type rather than a class named "T". It is feels somehow like "higher-order generics".

EDIT: I know I could try to extend Map and implement my own wrapper etc, but I am specifically asking about doing this just using using Java's generic support. I am more interested in the idea rather than this particular case.

EDIT 2: As pointed out below, this is a duplicate (or more specifically a subcase) of the question: Java map with values limited by key's type parameter . Had I been able to find wording as eloquent as that, I would have likely found that answer and not posted this.

Answer 1

You mean something like this ?

public class Favorites {
  private Map<Class<?>, Object> favorites =
    new HashMap<Class<?>, Object>();

  public <T> void setFavorite(Class<T> klass, T thing) {
    favorites.put(klass, thing);
  }

  public <T> T getFavorite(Class<T> klass) {
    return klass.cast(favorites.get(klass));
  }

  public static void main(String[] args) {
    Favorites f = new Favorites();
    f.setFavorite(String.class, "Java");
    f.setFavorite(Integer.class, 0xcafebabe);
    String s = f.getFavorite(String.class);
    int i = f.getFavorite(Integer.class);
  }
}

see as reference: Java map with values limited by key's type parameter