java 繼承示例

Prerequisite: Inheritance and its implementation in Java

先決條件： 繼承及其在Java中的實(shí)現(xiàn)

Java中的繼承類型 (Type of inheritance in Java)

In Java programming, there are following types of the inheritances,

在Java編程中，有以下幾種類型的繼承 ，

Single Inheritance

單繼承

Multiple Inheritances (Through Interface)

多重繼承(通過(guò)接口)

Multilevel Inheritance

多級(jí)繼承

Hierarchical Inheritance

層次繼承

1)單一繼承 (1) Single Inheritance)

If a class extends another class (i.e. the only one class).

如果一個(gè)類擴(kuò)展了另一個(gè)類(即唯一一個(gè)類)。

Syntax:

句法：

class Parent {// Fields and Methods}class Child extends Parent {// Fields and Methods}

Example of Single Inheritance:

單一繼承的示例：

/*Java program to demonstrate the concept of inheritance */// Parent class class Parent {// The Parent class has one method// displayParentMessage() method to print message of Parent Classpublic void displayParentMessage() {System.out.println("Hello, we are in parent class method");} }// Sub class or derived class class Child extends Parent {// The Child subclass adds one more method// displayChildMessage() method to print message of Parent Classpublic void displayChildMessage() {System.out.println("Hello, we are in child class method");} }// Main class in this class we will create //object of parent and child class class Main {public static void main(String[] args) {// Creation of Parent class objectParent p = new Parent();// Calling Parent class method by Parent class objectp.displayParentMessage();// Creation of Child class objectChild c = new Child();// Calling Child class method by Child class objectc.displayChildMessage();// Calling Parent class method by Child class objectc.displayParentMessage();} }

Output

輸出量

D:\Programs>javac Main.java D:\Programs>java Main Hello, we are in parent class method Hello, we are in child class method Hello, we are in parent class method

2)多重繼承(通過(guò)接口) (2) Multiple Inheritance (Through Interface))

If we extend more than one class. Java doesn’t support multiple inheritances directly but with the help of interface we can implement but it is similar to multiple inheritance.

如果我們擴(kuò)展多個(gè)類。 Java不直接支持多重繼承，但是借助我們可以實(shí)現(xiàn)的接口的幫助，它類似于多重繼承。

Syntax:

句法：

interface interface1 {// Field and Method declaration}interface interface2 {// Field and Method declaration}Class class_name implements interface1, interface2 {}

Example of Multiple Inheritance:

多重繼承的例子：

/*Java program to demonstrate the concept of multiple inheritance */interface Print {void print(); } interface Show {void show(); }class Main implements Print, Show {public void print() {System.out.println("Hello");}public void show() {System.out.println("World");}public static void main(String args[]) {Main obj = new Main();obj.print();obj.show();} }

Output

輸出量

D:\Programs>javac Main.javaD:\Programs>java Main Hello World

3)多級(jí)繼承 (3) Multilevel Inheritance)

If a classA extends by classB and classB extends by classC is called multilevel inheritance.

如果將classA擴(kuò)展為classB ，將classB擴(kuò)展為classC，則稱為多級(jí)繼承。

Syntax:

句法：

class classA {// Fields and Methods}class classB extends classA {// Fields and Methods}class classC extends classB {// Fields and Methods}

Example of Multilevel Inheritance:

多級(jí)繼承的示例：

/*Java program to demonstrate the concept of multilevel inheritance */// ClassA class class ClassA {// The ClassA class has one method// displayClassAMessage() method to print message of ClassA Classpublic void displayClassAMessage() {System.out.println("Hello, we are in ClassA class method");} }// ClassB class class ClassB extends ClassA {// The ClassB class adds one more method// displayClassBMessage() method to print message of ClassB Classpublic void displayClassBMessage() {System.out.println("Hello, we are in ClassB class method");} }// ClassC class class ClassC extends ClassB {// The ClassC class adds one more method// displayClassCMessage() method to print message of ClassC Classpublic void displayClassCMessage() {System.out.println("Hello, we are in ClassC class method");} }// Main class in this class we will create //object of ClassA and ClassB and ClassC class class Main {public static void main(String[] args) {// Creation of ClassA class objectClassA ca = new ClassA();// Calling ClassA class method by ClassA class objectca.displayClassAMessage();// Creation of ClassB class objectClassB cb = new ClassB();// Calling ClassB class method by ClassB class objectcb.displayClassBMessage();// Calling ClassA class method by ClassB class objectcb.displayClassAMessage();// Creation of ClassC class objectClassC cc = new ClassC();// Calling ClassC class method by ClassC class objectcc.displayClassCMessage();// Calling ClassB class method by ClassC class objectcc.displayClassBMessage();// Calling ClassA class method by ClassC class objectcc.displayClassAMessage();} }

Output

輸出量

D:\Programs>javac Main.javaD:\Programs>java Main Hello, we are in ClassA class method Hello, we are in ClassB class method Hello, we are in ClassA class method Hello, we are in ClassC class method Hello, we are in ClassB class method Hello, we are in ClassA class method

4)層次繼承 (4) Hierarchical Inheritance)

If more than one class is inherited from the base class is called hierarchical inheritance.

如果從基類繼承多個(gè)類，則稱為層次繼承。

Syntax:

句法：

class classA {// Fields and Methods}class classB extends classA {// Fields and Methods}class classC extends classA {// Fields and Methods}

Example of Hierarchical Inheritance:

層次繼承的示例：

/*Java program to demonstrate the concept of hierarchical inheritance *///ClassA class ClassA {// The ClassA class has one method// displayClassAMessage() method to print message of ClassA Classpublic void displayClassAMessage() {System.out.println("Hello, we are in ClassA class method");} }// ClassB class class ClassB extends ClassA {// The ClassB class adds one more method// displayClassBMessage() method to print message of ClassB Classpublic void displayClassBMessage() {System.out.println("Hello, we are in ClassB class method");} }// ClassC class class ClassC extends ClassA {// The ClassC class adds one more method// displayClassCMessage() method to print message of ClassC Classpublic void displayClassCMessage() {System.out.println("Hello, we are in ClassC class method");} }// Main class in this class we will create //object of ClassA and ClassB and ClassC class class Main {public static void main(String[] args) {// Creation of ClassA class objectClassA ca = new ClassA();// Calling ClassA class method by ClassA class objectca.displayClassAMessage();// Creation of ClassB class objectClassB cb = new ClassB();// Calling ClassB class method by ClassB class objectcb.displayClassBMessage();// Calling ClassA class method by ClassB class objectcb.displayClassAMessage();// Creation of ClassC class objectClassC cc = new ClassC();// Calling ClassC class method by ClassC class objectcc.displayClassCMessage();// Calling ClassA class method by ClassC class objectcc.displayClassAMessage();} }

Output

輸出量

D:\Programs>javac Main1.javaD:\Programs>java Main1 Hello, we are in ClassA class method Hello, we are in ClassB class method Hello, we are in ClassA class method Hello, we are in ClassC class method Hello, we are in ClassA class method

翻譯自: https://www.includehelp.com/java/types-of-inheritance-in-java-with-examples.aspx

java 繼承示例

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