Bounded type parameters

Bounded parameters means restricting the types that can be used as generic type arguments.

To force generic type to be a subclass of Shirt.

public class Drawer<T extends Shirt> {

  public void add(T shirt) {
  }
}

extends forces T to be a subclass of Shirt.

// usage
Drawer<Shirt> shirtDrawer = new Drawer<>();

Multiple bounded type parameter

public class Drawer<T extends Shirt & Comparable> {
}

Here, Shirt is class and Comparable is an interface. So, the type now must respect both upper bounds.

If one of the upper bounds is a class, it must be first argument.