Unit 9 Inheritance
Student Lesson
Lecture Notes with Vocab
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Inheritance: define a base class like a car class that has methods and attributes common. For example, there can be a car steering method, gas and break method, and attributes like speed -
Extend: Each car that is created will extend from this base class thus inheriting the methods and attributes defined in the base class- New car classes with have special features
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Super Class: Base class that has all the generic methods (base Car Class that has generic methods for all cars)-
protected: access modifier isn't affected by outside
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Subclass constructor: inherits all methods and attributes from super class- In car example, TeslaModelS was a subclass
- In personal example, IphoneX and IphoneV are subclasses
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super Keyword: superclass objects - used to call superclass methods and access the constructor- use constructors defined in the superclass
- can add specific attributes
- super() is the use of the keywords
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Overloadinga method (same name different parameters): two methods with the same name but different arguments; static polymorphism or compile time polymorphism -
Overridinga method (same signature of a method): subclass has specific implementation of a method that the superclass provides -
Polymorphism: doing one task in many ways through inheritance- gearShift in cars can be used in two different ways in two different classes - two implementations through overriding
public class Phone {
protected String brandName;
protected double version;
protected double cameraNumber;
protected double maxVolume;
// Constructor for the attributes present in the superclass
public Phone(String brandName, double version, double cameraNumber, double maxVolume) {
this.brandName = brandName;
this.version = version;
this.cameraNumber = cameraNumber;
this.maxVolume = maxVolume;
}
public void flash () {
System.out.println("On!");
}
public void homebutton () {
System.out.println("Yes!");
}
public void darkmode () {
System.out.println("on!");
}
public void powerbutton () {
System.out.println("turning on...");
}
public void camera () {
System.out.print("photo... ");
}
}
public class IphoneX extends Phone {
// Additional attribute not present in the superclass
protected String cameratype;
// Constructor for Subclass
public IphoneX(String brandName, double version, double cameraNumber, double maxVolume, String cameratype) {
// We use the Superclass constructor for the shared attributes through the keyword "super"
super(brandName, version, cameraNumber, maxVolume);
// hornSound is not in the Superclass, so we add it separately in the constructor
this.cameratype = cameratype;
}
// We use override to change the functionality in the subclass of an existing method in the superclass
@Override
public void darkmode () {
System.out.println("The screen is now dark!");
}
public void powerbutton () {
System.out.println("Iphone is on...");
}
// Here, we don't fully change the functionality of the existing horn method in the superclass
// Instead, we take all of the functionality of the superclass method, and then add on to it
public void camera () {
super.camera();
System.out.println(cameratype);
}
public static void main(String[] args) {
// 5 argument constructor
IphoneX modelS = new IphoneX("Tesla", 396, 4, 200, "taken");
// Example of late binding
Phone phone = new IphoneX("Tesla", 396, 4, 200, "saved");
// We can still use the methods from the child class, even though we didn't mention them in the subclass!
modelS.flash();
// Using the overridden method
modelS.darkmode();
modelS.homebutton();
modelS.powerbutton();
// Using the method we added on to
modelS.camera();
phone.camera();
}
}
IphoneX.main(null);
public class IphoneV extends Phone {
public IphoneV (String brandName, double version, double cameraNumber, double maxVolume) {
super(brandName, version, cameraNumber, maxVolume);
}
@Override
public void darkmode () {
System.out.println("Dark mode is on!");
}
public void dimensions (int a) {
System.out.println("Length is " + a);
}
public void dimensions (int a, int b) {
System.out.println("Length is " + a + " and height is " + b);
}
public static void main(String[] args) {
// 4 superclass argument constructor
IphoneV phone2 = new IphoneV("Apple", 348, 4, 145);
// Using the overridden method
phone2.darkmode();
// Using the overloaded method
phone2.dimensions(1);
phone2.dimensions(1, 1);
}
}
IphoneV.main(null);