Java
inheritance and programming example
What Is inheritance?
·
It is inheriting the properties
of parent class into child class. inheritance is the procedure by which one
object acquires all the properties and behavior of the parent object.
Important points of inheritance:--
1.
inheritance
is an achieve by using the “extends “ keyword
2.
every
class has a super o say parent class i.e object class (but object
class does not have any parent class).
Inheritance advantage:--
1.
Code reusability
2. We can archive polymorphism using the inheritance method overriding.
Type of inheritance:-
Java can achive 3 type
inheritance single inheritance, multilevel inheritance and hierarchical
inheritance.
 |
Disadvantage of inheritance:-
Using inheritance the two
classes (parent child class) gets tightly coupled.
Single inheritance:-- single
inheritance one class extends another
class(one class only). 
Multilevel inheritance:- multilevel
inheritance one class can inherit from a derived class. Hence the derived class becomes the base class for the new
class.
Hierarchical
inheritance:-- in hierarchical inheritance one class is inherited by many sub class.
Multiple inheritance:-- in multiple inheritance one class extends more than one classes.java does not support multiple inheritance.
Hybrid inheritance:-- hybrid
inheritance is a combination of any two inheritance. Java does not support
hybrid inheritance.
Below does not take part
inheritance :-
Constructor:- a sub –class inherit all the member (fields, method, and nested class) form its super class .constructor are not members so they are not inherited by sub-classes . but the constructor of the super class can be invoked from the sub-class.
Privet members:-- a sub
class does not inherit the privet member
of its parent class. How ever if the super class has public or protected
method(like getter and setter ) for accessing its privet fields .these can also
be used by the sub classes.
There can be
only one super class. not more than that because java does not support multiple
inheritance.
Programming example of single
inheritance:--
class SingleInheritance {
void show()
{
System.out.println(“parent
class”);
}
}
class Child
extends SingleInheritance {
void show1()
{
System.out.println(“child
class”);
}
public static void
amin(String args[]) {
Child obj = new
Child();
obj .show();
obj .show1();
}
}
Programming example of multilevel
inheritance:--
class MultilevelInheritance {
void show()
{
System.out.println(“parent
class”);
}
}
class Child
extends MultilevelInheritance {
void show1()
{
System.out.println(“child
class”);
}
class Sub_Child
extends Child
{
void show2()
{
System.out.println(“sub-child
class”);
}
public static void
amin(String args[]) {
Sub_Child obj = new Sub_Child ();
obj .show();
obj .show1();
obj .show2();
}
}
Programming example of
hierarchical inheritance:--
class HierarchicalInheritance {
void show()
{
System.out.println(“parent
class”);
}
}
class Child
extends HierarchicalInheritance {
void show1()
{
System.out.println(“child
class”);
}
class Sub_Child
extends HierarchicalInheritance {
void show2()
{
System.out.println(“sub-child
class”);
}
public static void
amin(String args[]) {
Sub_Child obj = new Sub_Child ();
obj .show2();
}
}
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