1. Lecture 8 Inheritance
CS140
Dick Steflik

2. Inheritance A class derived from another class is called a subclass
also a a derived or child class
The class that a subclass is derived from is called the super class
also the parent class
All classes are derived from class Object
class Object has no super class

3. Java Class Hierarchy
All Java objects are derived from class Object

4. An example public class Airplane{ public int speed, altitude, heading;
public Airplane( int s, int a, int h){
speed = s;
altitude = a;
heading = h; }
public setSpeed(int newSpeed)
{ speed = newSpeed; }
public setAltitude(int newAltitude)
{ altitude = newAltitude; }
public setHeading(int newHeading)
{ heading = newHeading; }
public faster( int increment)
{ speed += increment;}
public slower(int increment)
{ speed -= increment;}

5. a subclass of Airplane public class Fighter extends Airplane {
public int ammo, missiles;
public Fighter ( int initBullets, int initMissiles, initSpeed,
int initAltit, int initHeading) {
// let the super class initial its fields
super( initSpeed, initSpeed, initHeading);
ammo = initBullets;
missiles = initMissiles; }
public void launchMissile() { missile-- ;}
public void fireBurst( int count) { ammo -= count)

6. using the classes Fighter F18 = new F18(1000, 6, 0, 0, 0)
F18.setSpeed = 100;
while ( F18.getSpeed() < MACH1)
{ F18.faster(10);
F18.climb(10); }

7. Inherited public fields can be used directly
Inherited public methods can be used directly
you can declare new fields in the subclass that are not in the superclass
the constructor of the subclass can use the constructor of the super class
you can define new methods in the subclass that are not in the superclass
the subclass can have an instance method with the same signature as one in the superclass thus overriding it
you can write a new static method in the subclass that has the same signature as on in the super class thus hiding it
private fields and methods are not inherited