Packages - The Java Programming Language - page 696

not accessible in Concrete1 , thus the implementation of pac in Concrete1
does not override that in AbstractBase , so it is AbstractBase.pac that show
invokes. Both the pro and pub methods are accessible in Concrete1 and
get overridden, so the implementation from Concrete1 is used in show .
Next we define the class Concrete2 , which extends Concrete1 but is in the
same package P1 as AbstractBase : [2]
[2] Having an inheritance hierarchy that weaves in and out of a package is generally a very bad idea.
It is used here purely for illustration.
package P1;
import P2.Concrete1;
public class Concrete2 extends Concrete1 {
public void pri() { print("Concrete2.pri()"); }
public void pac() { print("Concrete2.pac()"); }
public void pro() { print("Concrete2.pro()"); }
public void pub() { print("Concrete2.pub()"); }
}
Each method of Concrete2 overrides the version from Concrete1 because
they are all public and therefore accessible. Also, because Concrete2 is
in the same package as AbstractBase , the method AbstractBase.pac is ac-
cessible in Concrete2 and so is overridden by Concrete2.pac . Invoking show
on a Concrete2 object prints
AbstractBase.pri()
Concrete2.pac()
Concrete2.pro()
Concrete2.pub()
Finally, we define the class Concrete3 , which extends Concrete2 but is in a
different package P3 :