java泛型中T和?的区别

class SuperClass<A>{}

public <T>void fromArrayToCollection(T[] a, Collection<T> c){}

class People<T>{
public void show(T a) {
   }
}

SuperClass<?> sup = new SuperClass<String>("lisi");
sup = new SuperClass<People>(new People());
sup = new SuperClass<Animal>(new Animal());

SuperClass<String> sup1 = new SuperClass<String>("lisi");
SuperClass<People> sup2 = new SuperClass<People>("lisi");
SuperClass<Animal> sup3 = new SuperClass<Animal>("lisi");