Inheritance in Java

Inherited

If some classes contain the same code, you can extract the same code into a new class, and then use the extends keyword to bring the original class and the new class into relationship---inheritance.

By inheritance, the original class is called the subclass (derived class), and the new class becomes the parent class (superclass/base class).

Subclasses can use a subset of the methods and properties in the parent class by inheriting the parent class

Note: Subclasses inherit all data fields (method + properties) of the parent class, but only a subset of the data fields are visible to the child class after inheritance

In Java, a subclass of single inheritance between classes and classes can inherit only one parent class, but a parent class can have multiple subclasses

The inheritance format of the class

In Java, the extends keyword can be used to declare that a class is inherited from another class in the following general form:

class classextends  parent class {} 

Instance:

Parent class:

 Public classAnimal {PrivateString name; Private intID;  PublicAnimal (String MyName,intmyID) {Name=MyName; ID=myID; }      Public voideat () {System.out.println (name+ "eating"); }     Public voidsleep () {System.out.println (name+ "Sleeping"); }     Public voidIntroduction () {SYSTEM.OUT.PRINTLN ("Hello, everyone!" I am "+ ID +" Number "+ Name +". "); } }

Penguin Category:

 Public class extends Animal {     publicint  myid) {         super(MyName, myID);}     }

Mouse Type:

 Public class extends Animal {     publicint  myid) {         super(MyName, myID);     } }

Inherited attributes

• Subclasses have properties that are not private to the parent class, methods.

• Subclasses can have their own properties and methods, that is, subclasses can extend the parent class.

• Subclasses can implement methods of the parent class in their own way.

• Java inheritance is a single inheritance, but can be multiple inheritance, single inheritance is a subclass can inherit only one parent class, multiple inheritance is, for example, Class A inherits Class B, Class B inherits Class C, so the Class C is the parent class of Class B, and Class B is the parent class of Class A, which is a feature that differs from C + + inheritance.

• Increases the coupling between classes (the disadvantage of inheritance, high coupling will cause the relationship between the code).

Inheritance in Java