Introduction to the author
Author name: Ming Shiyin in programming world
Introduction: CSDN blog expert has been engaged in software development for many years and is proficient in Java and JavaScript. Bloggers also learn and grow step by step from scratch, know the importance of learning and accumulation, and like to fight and upgrade with ADC. Welcome to pay attention and look forward to learning, growing and taking off with you!
introduction
Many Java beginners ask me that it's worrying for the novice to turn around and forget the Java knowledge he has studied very hard. How can Xiaobai grow up quickly and become a big cow?
In fact, there is only one skill to become a big God: "learn more and practice more", so brother Ming sorted out typical practice examples. Through practice, you can quickly improve coding skills and proficiency, so that you can never return on the way to become a big man (remember to practice with your own hands)!
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◄ previous article 79. Encapsulation of Java classes
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summary
Inheritance is one of the three characteristics of object-oriented.
Inheritance is that a subclass inherits the characteristics and behavior of the parent class, so that the subclass object (instance) has the instance domain and method of the parent class, or the subclass inherits the method from the parent class, so that the subclass has the same behavior as the parent class.
Inheritance format of class
Class parent class{
}
Class subclass extends parent class{
}
Why use inheritance
There are two classes, students and teachers. They have many things in common, such as name, age, gender, telephone and other attributes, as well as common methods such as eating and sleeping.
There are also some different things. For example, students have student numbers and teachers have teacher numbers (just write one)
Student class
package demo.demo80;
/*
* Student class
*/
public class Student {
//Property is private
private String name; // full name
private int age; // Age
private String sex; // Gender
private String phone; // contact number
private String sNo; //Student number
//Construction method
public Student(String name,int age,String sex,String phone,String sNo){
this.name=name;
this.age=age;
this.sex=sex;
this.phone=phone;
this.sNo=sNo;
}
//having dinner
public void eat(){
System.out.println(name+"be at table");
}
//sleep
public void sleep(){
System.out.println(name+"sleeping");
}
}
Teacher class
package demo.demo80;
/*
* Teacher class
*/
public class Teacher {
// Property is private
private String name; // full name
private int age; // Age
private String sex; // Gender
private String phone; // contact number
private String tNo; //Teacher number
// Construction method
public Teacher(String name, int age, String sex, String phone,String tNo) {
this.name = name;
this.age = age;
this.sex = sex;
this.phone = phone;
this.tNo = tNo;
}
// having dinner
public void eat() {
System.out.println(name + "be at table");
}
// sleep
public void sleep() {
System.out.println(name + "sleeping");
}
}
It can be seen from these two pieces of code that the code is repeated, resulting in a large amount of code and bloated.
Design People class
Extract the same things of Student class and Teacher class into People
package demo.demo80;
/*
* Parent class
*/
public class People {
// Property is private
private String name; // full name
private int age; // Age
private String sex; // Gender
private String phone; // contact number
// Construction method
public People(String name, int age, String sex, String phone) {
this.name = name;
this.age = age;
this.sex = sex;
this.phone = phone;
}
// having dinner
public void eat() {
System.out.println(name + "be at table");
}
// sleep
public void sleep() {
System.out.println(name + "sleeping");
}
}
Inherit to People class
Student class inheritance
package demo.demo80;
/*
* Student class
*/
public class Student extends People{
//Property is private
private String sNo; //Student number
//Construction method
public Student(String name,int age,String sex,String phone,String sNo){
super(name,age,sex,phone);
this.sNo=sNo;
}
}
Teacher class inheritance
package demo.demo80;
/*
* Teacher class
*/
public class Teacher extends People{
// Property is private
private String tNo; //Teacher number
//Construction method
public Teacher(String name,int age,String sex,String phone,String tNo){
super(name,age,sex,phone);
this.tNo=tNo;
}
}
Test it
package demo.demo80;
public class Test {
public static void main(String[] args) {
Student student = new Student("Zhang San",19,"male","13812345678","001");
student.eat();
student.sleep();
}
}
Operation results:
Zhang San is eating
Zhang San is sleeping
advantage
- Realize code sharing, reduce the workload of creating classes, and enable subclasses to have methods and properties of parent classes.
- Improve code maintainability and reusability.
- Improve the code scalability and better implement the method of parent class.
Summary
This section summarizes "Java extensions", hoping to be helpful to you. Please help [like] + [collection] + [punch in the comment area]. If you are interested in learning java with brother Xiaoming, [pay attention to a wave] won't get lost.
Let me know you by punching in the comment area. Mingge will continue to pay attention to your learning progress!
Navigation
✪ introduction to Java white 200 case series directory index
◄ previous article 79. Encapsulation of Java classes
► next article to be updated
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