1. Inherited Classes in Java
CSCI 392
Classes - Part 2

2. Recap from last week… Scope of Fields and Methods can be Constructors
public, private, protected
Constructors
syntax is just like C++
optional since fields can be initialized
"static" fields and methods belong to the entire class, not individual instances

3. What is Inheritance?
Building a new class by reusing everything in an existing class.
Subclasses can add to their base class's list of methods and fields, and can also replace inherited methods.
Animal
Fish
Mammal

4. Why use Inheritance?
So that you don't have to rewrite a bunch of code.
Better Maintenance: Correcting/Improving code in the base class fixes all the subclasses.

5. Declaring an Inherited Class
public class stack extends list {
The new stack class
is a subclass of the list class

6. What gets Inherited? All fields marked as "protected" or "public".
"private" fields are only visible to the class that declared them
"protected" fields are only visible to the class that declared them, and any subclasses
All methods marked protected or public.

7. public class list {
protected int[] values;
private int size;
...
public class stack extends list
public void some_method ()
values[i] = myinteger; // legal
size++; // illegal

8. Jargon Alert Overloading Overriding
creating multiple methods with the same name
example: multiple constructors may have the same name if they have different parameters
Overriding
replacing inherited methods
example: see next page

9. Override Overload public class SuperClass { public void method1 ()
{ ... }
public void method1 (int param1)
public void method2 () }
public class SubClass extends SuperClass
public void method2 (int param2)
Override
Overload

10. public class SuperClass{
public void method1 ()
{ ... }
public void method1 (int param1)
public void method2 () }
public class SubClass extends SuperClass
public void method2 (int param2)
...
SubClass bob = new SubClass();
bob.method1();
bob.method2();
bob.method1(99);

11. Using the Parent's Constructor
public class ParentClass {
public ParentClass (int param)
{ do a bunch of work }
... }
==================================
public class ChildClass extends ParentClass
public ChildClass (int param)
super (param)