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Java. Powered By: Arvind Department of Computer science and engineering Radha govind group of institutions,meerut. Inheritance.

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Java

Java

Powered By:

Arvind

Department of Computer science and engineering

Radha govind group of institutions,meerut


Inheritance
Inheritance

  • Inheritance provides a mechanism that allow a class to inherit property of another class when extends another class it inherits all non-private members including fields and methods.

  • Inheritance defines is a relationship between super class and sub class.

  • extends and implements keywords are used to describe inheritance In java.

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Java

class Car{

…………………

}

class Maruti extends Car{

……………………… //extends the property of car class

}

  • Car is a super class of maruti

  • Maruti is sub class of Car

  • Maruti is- a Car

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Purpose of inheritance
Purpose of inheritance

  • To promote code reuse

  • To use polymorphism

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Type of inheritance
Type of Inheritance

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Example of simple inheritance
Example of Simple inheritance

class Parent{ public void get() { System.out.println(“The Parent method”); }}public class Child extends Parent{ public void set() {System.out.println(“The Child method”); }}

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Java

public static void main(String[] args) { Child obj=new Child();obj.set();obj.get(); }}

Output:

The Parent methodThe Child method

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Output
Output

  • Sports car

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Why multiple inheritance is not supported in java
Why multiple inheritance is not supported in Java

  • To remove ambiguity.

  • To provide more maintainable and clear design.

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Super keyword
Super keyword

  • In java, super keyword is used to refer to immediate parent class of class.

  • In other words super keyword is used by a subclass whenever it need to refer to its immediate parent class.

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Example of child class referring parent class using super keyword
Example of Child class referring Parent class using super keyword

class Parent{ String name;}public class Child extends Parent{

String name; public void details() { super.name=“Parent”; name=“Child”; System.out.println(super.name+“ and ”+name); } public static void main(String[] args) { Child obj=new Child(); obj.details(); }}Output: Parent and Child

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Example of child class referring parent class methods using super keyword
Example of Child class referring Parent class methods using super keyword

class Parent{ String name; public void details() { name=“Parent”; System.out.println(“Parent”); }}

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Java

public class Child extends Parent{

String name; public void details() { super. details(); name=“Child”; System.out.println(name); } public static void main(String[] args) { Child obj=new Child(); obj.details(); }}Output: Parent Child

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Example of child class calling parent class constructor using super keyword
Example of Child class calling Parent class constructor using super keyword

class Parent{ String name; public parent(String n) {name=n; }}public class Child extends Parent{

public Child(String n1,String n2) { super(n1); name=n2; }

}

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Java

public void details() {System.out.println(super.name+”and”+name); } public static void main(String[] args) { Child obj=new Child(“Parent”,”child”); obj.details(); }}

Output: Parent and Child

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Java

  • Can you use both this() and super() in a Constructor?

    Because both super() and this() must be first statement inside a constructor. Hence we cannot use them together.

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Multilevel inheritance
Multilevel Inheritance

class Person{ String name;intage; void getdata(String a,int b) { name=a; age=b; }}

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Java

  • class Teacher extends Person{ String qualification; float salary; void getqual(String s) { qualification =s; } void getsal(float a) { salary=a; }

    void display( ) { System.out.println(“Name of teacher=”+name); System.out.println(“Age of teacher=”+age); System.out.println(“Qualification of teacher=”+qualification); System.out.println(“Salary of teacher=”+salary); }}

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Java

  • class guestTeacher extends Teacher{ float ppl;  //pay per lecture void getppl(float a) {ppl=a; } void display( ) { System.out.println(“Name of teacher=”+name); System.out.println(“Age of teacher=”+age); System.out.println(“Qualification of teacher=”+qualification); System.out.println(“Payment per lecture=”+ppl); }}

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Java

  • class testInheritance{

  • public static void main(String args[ ]){Teacher teach=new Teacher( );teach.getdata(“Ajay”,50);teach.getqual(“Msc”);teach.getsal(1200);teach.display( );guestTeachergteach=new guestTeacher( );gteach.getdata(“Aman”,30);gteach.getqual(“Phd”);gteach.getppl(800);gteach.display( );}}

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Java

class Account { String cust_name; intacc_no; Account(String a, int b) {cust_name=a;

acc_no=b; }

void display() {

System.out.println ("Customer Name: "+cust_name);

System.out.println ("Account No: "+acc_no); } }

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Java

class Saving_Acc extends Account {

intmin_bal,

saving_bal;

Saving_Acc(String a, int b, int c, int d)

{

super(a,b);

min_bal=c;

saving_bal=d;

}

void display()

{

super.display();

System.out.println ("Minimum Balance: "+min_bal);

System.out.println ("Saving Balance: "+saving_bal);

}

}

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Java

class Acct_Details extends Saving_Acc

{

int deposits, withdrawals;

Acct_Details(String a, int b, int c, int d, int e, int f)

{

super(a,b,c,d);

deposits=e;

withdrawals=f;

}

void display()

{

super.display();

System.out.println ("Deposit: "+deposits);

System.out.println ("Withdrawals: "+withdrawals);

}

}

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Java

class q9Multilevel

{

public static void main(String args[])

{

Acct_Details A = new Acct_Details("Pa.one",666,1000,5000,500,9000);

A.display();

}

}

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Java

Class X

{

public void methodX()

{

System.out.println("Class X method");

}

}

Class Y extends X

{

public void methodY()

{

System.out.println("class Y method");

}

}

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Java

Class Z extends Y

{

public void methodZ()

{

System.out.println("class Z method");

}

public static void main(String args[])

{

Z obj = new Z();

obj.methodX(); //calling grand parent class method

obj.methodY(); //calling parent class method

obj.methodZ(); //calling local method

}

}

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Hierarchical inheritance
Hierarchical Inheritance

class base_class_name{…………….…………….}class derived_class_name1 extends base_class_name{…………………………}class derived_class_name2 extends base_class_name{…………..…………..}

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Java

  • class Base{

    void showBase() { System.out.println(“Base class method”); }}

    class Derived1 extends Base{ void showDerived1() { System.out.println(“method of Derived1″); }}

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Java

class Derived2 extends Base{ void showDerived2() { System.out.println(“method of Derived2″); }}

class TestHierarchical{public static void main(String args[]){ Derived1 d1=new Derived1(); Derived2 d2=new Derived2(); d1.showDerived1(); d1.showBase(); d2.showDerived2(); d2.showBase();}}

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