Java Inheritance.pdf of java in computer language

Java Inheritance.pdf of java in computer language

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  Java Inheritance
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  After learning you shouldbe able to do.. Introduction About inheritance Types of inheritance And its programs. 2
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  Introduction to Inheritance.. Presentationtitle 3
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  Definition • When youconstruct a new class from existing class in such a way that the new class access all the features and properties of existing class is called inheritance. • In java extends keyword is used to perform inheritance. • It provides code reusability. • We can’t access private members of class through inheritance. • A subclass contains all the features of superclass. So, we should create the object of subclass. • Method overriding only possible through inheritance. 4
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  SYNTAX FOR USINGINHERITANCE
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  Class A { ________________ //code _____________ ____ } classB extends A //subclass { _____________ //code ____________ } 6
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  Types of inheritance
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  1. Simple inheritance Simple inheritanceis nothing but which contain only one super class and only one sub class. Syntax- class Super { ____________ ____________ } Class Sub extends Super { ______________ _____________ } 8
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  9 • Class Student •{ • int roll , marks; • String name; • void input() • { • System . out . println (“enter roll , name , and marks”); • } • } • Class Ankit extends Student //sub class • { • Void disp () • { • Roll=1; name=“Rahul”; marks=89; • System . out . println (“roll+” ”+ name+” ”+marks”); • } • public static void main(String [] args) • { • Ankit r=new Ankit(); • r . input(); • r . disp(); • } • }
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  If we declaremethod or data member as private, it will show error because private member can only access only inside same class but not in other class object . But in inheritance declare as public or protected to access it easily. Presentation title
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  Multilevel Inheritance In multilevelinheritance , we have only one superclass and multiple sub classes. Presentation title 11
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  Syntax for multilevel inheritance Presentationtitle 12 • Class Super • { • __________ • ___________ • ______________ • } • class sub1 extends Super • { • _______ • __________ • } • class sub2 extends sub1 • { • __________ • _______________ • }
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  • class A •{ • int a , b , c ; • void add() • { • a=10 ; b=20 ; • c=a+b; • System.out.println(“sum of two numbers”+c); • } • void sub() • { 13
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  • a=200;b=100; • c=a-b; •System.out.println(“sub of two numbers”+c); • }} • class B extends A • { • void multi() • { • a=10;b=20; • C=a*b; • System.out.println(“multiplication of two numbers ”+c); • } • void div() • { • a=10;b=2; • c=a/b; • System.out.println(“division of the two numbers”+c); • } } • class C extends B • { • void rem() • { • A=10;b=3; • C=a%b; • System.out.println(“remainder of two numbers”+c); • } } • Class Test • { • Public static void main(String[]args) • { • C r=new C; • r . add(); r . sub(); r . multi(); r . div(); r . rem(); • } } 14
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  Multiple inheritance whenever asub class wants to inherit the property of two or more superclasses that have same method , java compiler can’t decide which class method it should inherit . Then their might be a chance of memory duplication i.e a reason java doesn’t support multiple inheritance through classes. Presentation title 15
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  Hierchical inheritance A inheritance whichcontain only one superclass and multiple subclass and all sub class directly extends super class is called hierchical inheritance. SYNTAX-class A { ____________ _______________ //code } Class B extends A { ____________ _______________ //code } Class C extends A { ___________________ //code }
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  • class A •{ • void input() • { • System.out.println(“enter your name”); • } } • class B extends A • { • void show() • { • System.out.println(“my name is Ankit”); • } } • class C extends A • { • void disp() • { • System.out.println(“my name is Ankush”); • } } • class Demo • { • Public static void main(String[]args) • { • B r=new B(); • C r2=new C(); • r.input(); • r.show(); • r2.input(); • r2.disp(); • } • } Presentation title 17