class type paramaters

So am getting comfortable with generics as I go trough my Thinking in java book. I understand concept and how easier things can be with generics, like when creating constructor , method or even a field. But I just can not understand why do in most of examples they are in the class declaration like : public class LinkedStack<T> {}. please help me understand

It doesn't make much sense to use instance-level generics without a class-level generic declaration.

For example:

Code java:

---

class ClassA
{
    T b;
 
    T getB(T param)
    {
        return b;
    }
}

---

Is field b expected to be a generic type, or is there actually class T? There's no way to tell. You must specify a class generic in order to clarify this.

Code java:

---

class ClassA<T>
{
    T b;
 
    T getB(T param)
    {
        return b;
    }
}

---

Now it's understood that T is a generic type, and every instance of T should be replaced by the actual type.