Question

I have one interface IMyInterface. A set of classes that implements this interface : Class1, Class2…

Now i want to create a Hashtable that stores any class implementing IMyInterface.

Hashtable<String,? extends IMyInterface> ht = new Hashtable<String,? extends IMyInterface>();
ht.add("foo",new Class1());

The compiler complains that it cannot instiate ht and that it cannot add Class1 because
the add method is not defined to do so. add method expects IMyInterface :\

How can i do ?

Answer 1

Simply use:

Hashtable<String, IMyInterface> table = new Hashtable<String, IMyInterface>();
table.put("foo", new Class1());

Given that Class1 implements IMyInterface.