class SimpleInheritance {
public static void main(String args[]) {
A superOb = new A();
B subOb = new B();
// The superclass may be used by itself.
superOb.i = 10;
superOb.j = 20;
System.out.println("Contents of superOb: ");
superOb.showij();
System.out.println();
/* The subclass has access to all public members of
its superclass. */
subOb.i = 7;
subOb.j = 8;
subOb.k = 9;
System.out.println("Contents of subOb: ");
subOb.showij();
subOb.showk();
System.out.println();
System.out.println("Sum of i, j and k in subOb:");
subOb.sum();
}
}
The output from this program is shown here:
Contents of superOb:
i and j: 10 20
Contents of subOb:
i and j: 7 8
k: 9
Sum of i, j and k in subOb:
i+j+k: 24
As you can see, the subclass B includes all of the members of its superclass, A. This is
why subOb can access i and j and call showij( ). Also, inside sum( ), i and j can be referred
to directly, as if they were part of B.
Even though A is a superclass for B, it is also a completely independent, stand-alone
class. Being a superclass for a subclass does not mean that the superclass cannot be used
by itself. Further, a subclass can be a superclass for another subclass.
The general form of a class declaration that inherits a superclass is shown here:
class subclass-name extends superclass-name {
// body of class
}
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