1 - Introduction
Inheritance in Java is a process in which a class acquires the properties (attributes and methods) of another Java class. With the use of inheritance, data and information are managed in a well organized and structured hierarchical order.
The class that inherits the properties of another class is called the subclass (derived class or daughter class) and the class whose properties are inherited is called superclass (base class, parent class, parent class ...).
Declaring a subclass is done using the Extends keyword
Extends is the keyword used to inherit properties from a class.
Syntax
Class mother {
....
}
Class daughter extends mother {
.....
}
2 - Java Inheritance: Example Study
To understand Java inheritance, we will treat a simple example of a human class and a subclass Employee
The human class is endowed with attributes:
- name
- age
- address
An employee is also a human and therefore the employee subclass inherits the same properties name,
age, address ... of the human super class , nevertheless the sub class employee possesses other attributes
that do not exist in the super class as salary, grade ...
Note :
The inheritance of an attribute is done with the keyword super
Example (supr class)
Package Humain;
Public class Human {
Public String name;
Public Human (String n) {
this.name = n;
}
}
Example (daughter class)
Package Humain;
Class Employee extends Human {
Public int salary;
Public Employee (String nm, int sal) {
super (nm);
this.salairy = sal;
}
Public static void main (String [] args) {
Employee teacher = new Employee ("Robert", 7500);
System.out.println ("The teacher's name is" + teacher.name);
System.out.println ("Teacher's salary is :" + teacher.salary + " $");
}
}
What will displays after execution:
The teacher's name is is Robert
Teacher's salary is : 7500 $
