Java object-oriented (inheritance)

Inherits the abstraction of a batch of classes, reduces the amount of code, facilitates the modification of the method, and manages the class.

Subclasses cannot inherit from parent class: ① constructor method ② private property and method ③ Use default modifier not under the same package

Inheritance initialization: Parent class Property, parent class, child class property, subclass constructor method

Inheritance: ① overload ② override ③ Interface ④ parent class object reference to Child class object

Rewrite rule: ① method name ② parameter list same ③ return value type is same or its subclass ④ access adornment permission cannot be strict with parent class

Private (This class) >default (same package) >protected (same package and sub-category) >public (All)

The Super/this keyword cannot be applied to the static decoration method

Package com.huidao.day10;

/* Question:

Realize the host and pet play function

Play a Frisbee game with your dog.

Play swimming games with penguins.

------Inheritance

Analysis:

How to add a Frisbee to dog Catchingflydisc ()

Add Swimming method to Penguin swimming ()

Add the play (Pet Pet) method to the owner */

public class Test03 {

public static void Main (string[] args) {

Master master = new Master ();

Pet dog = new Dog ();

Master.play (dog);

Pet penguin = new Penguin ();

Master.play (Penguin);

}

}

Class master{

Pet Pet;

public void Play (Pet pet) {

Pet.shout ();

if (pet instanceof Dog) {

Dog dog = (dog) pet;

Dog.catchingflydisc ();

} else if (pet instanceof Penguin) {

Penguin Penguin = (Penguin) pet;

Penguin.swimming ();

}

}

}

Class pet{

public void Shout () {}

}

Class Dog extends pet{

Overridden methods

public void shout () {

System.out.println ("Barking Dog");

}

Common methods

public void Catchingflydisc () {

System.out.println ("Pick up the Frisbee");

}

}

Class Penguin extends pet{

public void shout () {

System.out.println ("Penguin bark");

}

public void swimming () {

System.out.println ("swimming");

}

}

Java object-oriented (inheritance)