Java/C3/Polymorphism/English-timed - Revision history

PoojaMoolya at 07:31, 8 December 2017

2017-12-08T07:31:36Z

Sandhya.np14 at 07:00, 18 May 2017

2017-05-18T07:00:47Z

Sandhya.np14 at 17:58, 17 May 2017

2017-05-17T17:58:25Z

Pratik kamble at 13:59, 20 February 2017

2017-02-20T13:59:56Z

PoojaMoolya: Created page with " {| Border=1 | '''Time''' | '''Narration''' |- | 00:01 | Welcome to the '''spoken-tutorial '''on '''Polymorphism in Java.''' |- | 00:06 | In this tutorial we will learn :..."

2016-08-12T08:44:46Z

Created page with " {| Border=1 | '''Time''' | '''Narration''' |- | 00:01 | Welcome to the '''spoken-tutorial '''on '''Polymorphism in Java.''' |- | 00:06 | In this tutorial we will learn :..."

New page

{| Border=1
| '''Time'''
| '''Narration'''

|-
| 00:01
| Welcome to the '''spoken-tutorial '''on '''Polymorphism in Java.'''

|-
| 00:06
| In this tutorial we will learn :

* About '''Polymorphism''' in Java
* '''Run-time polymorphism'''
* '''Virtual Method Invocation''' and
* '''Compile-time polymorphism'''

|-
| 00:19
| Here we are using
* '''Ubuntu Linux Version 12.04'''
* '''JDK Version 1.7''' and
* '''Eclipse 4.3.1'''

|-
| 00:31
| To follow this tutorial, you must have basic knowledge of '''Java and Eclipse IDE.'''

|-
| 00:37
| You must have knowledge of '''Subclassing '''& '''Method overriding and overloading'''

|-
| 00:43
| If not, for relevant '''Java''' tutorials, please visit our website.

|-
| 00:48
| '''Polymorphism''' is an ability of an object to take on many forms.

|-
| 00:54
| The major advantages of '''Polymorphism '''are:

1. Reduction of complexity &

2. Code re-usability

|-
| 01:03
| In '''Java''', there are two types of '''polymorphism''': '''Compile-time''' and '''Run-time polymorphism.'''

|-
| 01:11
| '''Compile-time polymorphism''' is essentially refered as '''Method overloading'''. It is also called '''Static Binding'''.

|-
| 01:20
| '''Run-time polymorphism''' is essentially referred as '''Method overriding'''. It is also called '''Dynamic Binding.'''

|-
| 01:29
| We have already learnt '''Run-time polymorphism''' i.e. '''Method overriding'''.

|-
| 01:35
| Let us switch to '''Eclipse IDE.''' I have already created a project named '''MyProject''' in the previous tutorial.

|-
| 01:44
| Let us take the code files of '''Using final keyword '''tutorial.

|-
| 01:49
| '''Employee '''class is the parent class.

|-
| 01:52
| '''Manager '''class is the subclass.

|-
| 01:55
| '''Manager''' class contains an additional variable '''department.'''

|-
| 02:01
| '''Manager '''class method '''getDetails()''' overrides the '''Employee '''class method '''getDetails().'''

|-
| 02:08
| We are calling the '''getDetails()''' method by '''Manager '''class object i.e. '''Manager.'''

|-
| 02:16
| In order to print the details, type '''system.out.println Details of Manager Class.'''

|-
| 02:28
| '''Save '''and run the program. So we can see '''department''' variable value in the output.

|-
| 02:37
|Therefore '''subclass''' method is invoked at '''runtime'''.

|-
| 02:42
| Method invocation is determined by the '''JVM,''' not compiler.

|-
| 02:48
|Therefore it is known as '''Runtime polymorphism''' or '''method overriding.'''

|-
| 02:55
| We learnt what is '''Run time polymorphism.'''

|-
| 02:58
| Now let us learn '''Virtual Method Invocation.'''

|-
| 03:03
| Come to '''Employee '''class in '''Eclipse IDE'''.

|-
| 03:07
| Remove the '''static '''and '''final''' keywords for variable '''name.'''

|-
| 03:13
| Uncomment the method '''setName'''.

|-
| 03:16
| Remove the '''static '''block. '''Save''' the file.

|-
| 03:21
| Come to '''TestEmployee '''class. Uncomment the value instance, '''manager.setName(“Nikkita Dinesh”);'''

|-
| 03:31
|We uncommented this instance, as we have uncommented the method '''setName() '''in '''Empolyee''' class.

|-
| 03:38
| Now, let's instantiate '''Employee''' object '''emp1''' for '''Employee '''class reference.

|-
| 03:46
|Type, '''Employee emp1 = new Employee open and close parenthesis semicolon'''

|-
| 03:57
| Let's initialize the value for '''setEmail '''and '''setName''' for '''Employee '''class.

|-
| 04:03
|Type, '''emp1.setName("Jayesh");''' '''emp1.setEmail("pqr@gmail.com");'''

|-
| 04:16
| In order to print the employee details type, '''System.out.println("Details of Employee class:" emp1.getDetails()) semicolon'''

|-
| 04:37
| Let us instantiate '''Manager '''object '''emp2 '''for '''Employee '''class reference i.e.

type '''Employee emp2 = new Manager open and close parenthesis semicolon'''

|-
| 04:54
| We are able to do this because any '''Java''' object that pass more than one '''IS-A '''test, is polymorphic.

|-
| 05:04
|In '''Java''', all objects are polymorphic, since any object will pass the '''IS-A '''test for their own type and for the class Object.

|-
| 05:16
|* A Manager '''IS-A''' Employee
* A Manager '''IS-A''' Manager
* A Manager '''IS-A''' Object

|-
| 05:23
| Only possible way to access an object is through a '''reference variable'''.

|-
| 05:29
|'''Reference variables''' like '''emp1, emp2 '''and '''manager.'''

|-
| 05:36
|Here, we instantiated two '''Manager''' objects:

*One which references '''Employee '''class.
*And other which references '''Manager '''class.

|-
| 05:47
| Let’s initialize the values for '''setEmail, setName''' and '''setDepartment '''using '''emp2''' object.

|-
| 05:55
|Type,

'''emp2.setName("Ankita");'''

'''emp2.setEmail(“xyz@gmail.com”);'''

'''emp2.setDepartment(“IT”);'''

|-
| 06:14
| We see that there is an error, '''The method setDepartment(String) is undefined for the type Employee'''

|-
| 06:23
| This is because, '''setDepartment '''method does not exist for '''Employee '''class.

|-
| 06:30
| So, remove the line, '''emp2.setDepartment("IT");'''

|-
| 06:37
| In order to print the details, type, '''System.out.println("Details of Manager class:" emp2.getDetails()) semicolon'''

|-
| 06:55
| '''Save '''and '''Run '''the program.

|-
| 06:58
| Here in the output. We get the '''Manager of: '''as blank.

|-
| 07:04
|This is because we have not initialized '''department''' in '''Manager '''class using '''emp2'''.

|-
| 07:12
| For demo purpose, let the default '''department''' be '''IT'''.

|-
| 07:17
|So, go to '''Manager '''class and initialize the value for '''department.'''

|-
| 07:25
| '''Save''' and '''run''' the program.

|-
| 07:28
| We get the output: '''Employee''' object referring '''Employee''' class,

|-
| 07:34
|'''Manager''' object referring '''Employee''' class & '''Manager '''object referring '''Manager '''class,

|-
| 07:42
| Here we see that the '''getDetails() '''method of '''Manager''' class is called by '''emp2'''.

|-
| 07:49
|But when '''emp2''' tried calling '''setDepartment''', we got an error.

|-
| 07:54
| The reason for that is as follows:

The compiler sees the '''getDetails()''' method in the '''Employee''' class during '''emp2.getDetails()'''.

|-
| 08:05
|So, it does not throw an error and validates the code.

|-
| 08:10
|At run time, however, the '''JVM''' invokes '''getDetails()''' in the '''Manager''' class as '''getDetails() '''of '''Manager '''class overrides '''getDetails() '''of '''Employee '''class.

|-
| 08:24
|So, we get the output as per '''getDetails() '''of '''Manager '''class. But the compiler does not see the '''setDepartment''' method in the '''Employee '''class.

|-
| 08:36
|Therefore, it raises an error in case of '''setDepartment''' call by '''emp2'''.

|-
| 08:43
| Here, '''Employee '''method '''getDetails()''' is invoked for '''Employee '''class.

|-
| 08:49
|The compiler references '''Employee''' class for '''getDetails()''' during '''emp1.getDetails().'''

|-
| 08:57
|At run time, the '''JVM''' invokes '''getDetails()''' in the '''Employee''' class. So we get the output as per '''getDetails() '''of '''Employee '''class.

|-
| 09:08
| Thus the '''JVM''' calls the appropriate method for the object that is referred to in each variable.

|-
| 09:16
|This behavior is referred to as '''Virtual Method Invocation.'''

|-
| 09:21
|The methods are referred to as '''Virtual Methods'''.

|-
| 09:26
| All methods in '''Java''' behave in this manner.

|-
| 09:31
| We successfully learnt what is '''Virtual Method Invocation.'''

|-
| 09:36
| We have already learnt '''Compile-time polymorphism '''i.e. method overloading.

|-
| 09:42
|Let us quickly know '''Compile time polymorphism '''in brief.

|-
| 09:47
|In '''Compile time polymorphism''', class can have more than one method.

|-
| 09:53
|The methods have same name but with different number of arguments.

|-
| 09:59
|Compiler is able to figure out the method call at compile-time. That’s the reason it is known as '''compile time polymorphism.'''

|-
| 10:09
| So, let us summarize.

|-
| 10:11
| In this tutorial we learnt:

* What is '''Polymorphism''' in Java?
* '''Run-time polymorphism'''
* '''Virtual Method Invocation''' and
* '''Compile-time polymorphism'''

|-
| 10:23
| As an assignment,

Override methods for '''Vehicle''' and '''Bike class''' which we used in previous tutorials.

|-
| 10:32
| The video available at the following link summarizes the Spoken Tutorial project. Please watch it.

|-
| 10:40
| The Spoken Tutorial Project Team conducts workshops and gives certificates to those who pass an online test.

For more details, please write to us.

|-
| 10:51
| Spoken Tutorial Project is supported by NMEICT, MHRD, Government of India.

More information on this Mission is available at this link.

|-
| 11:03
| Thats it for the tutorial. This is Trupti Kini from IIT Bombay signing off. Thank you for joining.

|}

@@ Line 12: / Line 12: @@
 | In this tutorial, we will learn about:
-* '''Polymorphism''' in Java
+'''Polymorphism''' in Java
-* '''Run-time polymorphism'''
+'''Run-time polymorphism'''
-* '''Virtual Method Invocation''' and
+'''Virtual Method Invocation''' and
-* '''Compile-time polymorphism'''.
+'''Compile-time polymorphism'''.
 |-
@@ Line 24: / Line 24: @@
 | Here we are using:
-* '''Ubuntu Linux Version 12.04'''
+'''Ubuntu Linux Version 12.04'''
-* '''JDK Version 1.7''' and
+'''JDK Version 1.7''' and
-* '''Eclipse 4.3.1'''
+'''Eclipse 4.3.1'''
 |-
@@ Line 355: / Line 355: @@
 |-
 | 10:11
-| In this tutorial, we learnt:
+| In this tutorial, we learnt: What is '''Polymorphism''' in Java?
-* What is '''Polymorphism''' in Java?
-* '''Run-time polymorphism'''
+'''Run-time polymorphism'''
-* '''Virtual Method Invocation''' and
+'''Virtual Method Invocation''' and
-* '''Compile-time polymorphism'''.
+'''Compile-time polymorphism'''.
 |-
@@ Line 375: / Line 374: @@
 |-
 | 10:40
-| The Spoken Tutorial Project Team:
+| The Spoken Tutorial Project Team: conducts workshops and gives certificates to those who pass an online test.
-* conducts workshops and
-* gives certificates to those who pass an online test.
 For more details, please write to us.

@@ Line 96: / Line 96: @@
 |-
 | 02:08
-| We are calling the '''getDetails()''' method by '''Manager '''class object i.e. '''Manager.'''
+| We are calling the '''getDetails()''' method by '''Manager '''class '''object''' i.e. '''Manager.'''
 |-
@@ Line 156: / Line 156: @@
 |-
 | 03:46
-|Type, '''Employee emp1 = new Employee open and close parenthesis semicolon'''
+|Type: '''Employee emp1 = new Employee open and close parenthesis semicolon'''
 |-
@@ Line 164: / Line 164: @@
 |-
 | 04:03
-|Type, '''emp1.setName("Jayesh");''' '''emp1.setEmail("pqr@gmail.com");'''
+|Type: '''emp1.setName("Jayesh");''' '''emp1.setEmail("pqr@gmail.com");'''
 |-
 | 04:16
-| In order to print the employee details type, '''System.out.println("Details of Employee class:"  emp1.getDetails()) semicolon'''
+| In order to print the employee details, type: '''System.out.println("Details of Employee class:"  emp1.getDetails()) semicolon'''
 |-
@@ Line 174: / Line 174: @@
 | Let us instantiate '''Manager '''object '''emp2 '''for '''Employee '''class reference i.e.
-type '''Employee emp2 = new Manager open and close parenthesis semicolon'''
+type: '''Employee emp2 = new Manager open and close parenthesis semicolon'''
 |-
 | 04:54
-| We are able to do this because any '''Java''' object that pass more than one '''IS-A '''test, is polymorphic.
+| We are able to do this because any '''Java object''' that pass more than one '''IS-A '''test, is polymorphic.
 |-
 | 05:04
-|In '''Java''', all objects are polymorphic, since any object will pass the '''IS-A '''test for their own type and for the class Object.
+|In Java, all objects are polymorphic, since any object will pass the '''IS-A '''test for their own type and for the class Object.
 |-
 | 05:16
 |A Manager '''IS-A''' Employee
 A Manager '''IS-A''' Manager
 A Manager '''IS-A''' Object
 |-
@@ Line 201: / Line 203: @@
 | 05:36
 |Here, we instantiated two '''Manager''' objects:
 One which references '''Employee '''class.
 And other which references '''Manager '''class.
@@ Line 221: / Line 222: @@
 |-
 | 06:14
-| We see that there is an error, '''The method setDepartment(String) is undefined for the type Employee'''
+| We see that there is an error, "The method setDepartment(String) is undefined for the type Employee".
 |-
@@ Line 229: / Line 230: @@
 |-
 | 06:30
-| So, remove the line, '''emp2.setDepartment("IT");'''
+| So, remove the line: '''emp2.setDepartment("IT");'''
 |-
 | 06:37
-| In order to print the  details, type, '''System.out.println("Details of Manager class:"  emp2.getDetails()) semicolon'''
+| In order to print the  details, type: '''System.out.println("Details of Manager class:"  emp2.getDetails()) semicolon'''
 |-
@@ Line 241: / Line 242: @@
 |-
 | 06:58
-| Here in the output. We get the '''Manager of: '''as blank.
+| Here in the output, we get the '''Manager of: '''as blank.
 |-
 | 07:04
-|This is because we have not initialized '''department''' in '''Manager '''class using '''emp2'''.
+|This is because, we have not initialized '''department''' in '''Manager '''class using '''emp2'''.
 |-
@@ Line 265: / Line 266: @@
 |-
 | 07:34
-|'''Manager''' object referring '''Employee''' class & '''Manager '''object referring '''Manager '''class,
+|'''Manager''' object referring '''Employee''' class & '''Manager '''object referring '''Manager '''class.
 |-
@@ Line 278: / Line 279: @@
 | 07:54
 | The reason for that is as follows:
 The compiler sees the '''getDetails()''' method in the '''Employee''' class during '''emp2.getDetails()'''.
@@ Line 287: / Line 287: @@
 |-
 | 08:10
-|At run time, however, the '''JVM''' invokes '''getDetails()''' in the '''Manager''' class as '''getDetails() '''of '''Manager '''class overrides '''getDetails() '''of '''Employee '''class.
+|At '''run''' time, however, the '''JVM''' invokes '''getDetails()''' in the '''Manager''' class as '''getDetails() '''of '''Manager '''class overrides '''getDetails() '''of '''Employee '''class.
 |-
@@ Line 307: / Line 307: @@
 |-
 | 08:57
-|At run time, the '''JVM''' invokes '''getDetails()''' in the '''Employee''' class. So we get the output as per '''getDetails() '''of '''Employee '''class.
+|At run time, the '''JVM''' invokes '''getDetails()''' in the '''Employee''' class. So, we get the output as per '''getDetails() '''of '''Employee '''class.
 |-
 | 09:08
-| Thus the '''JVM''' calls the appropriate method for the object that is referred to in each variable.
+| Thus the '''JVM''' calls the appropriate method for the '''object''' that is referred to in each variable.
 |-
@@ Line 339: / Line 339: @@
 |-
 | 09:47
-|In '''Compile time polymorphism''', class can have more than one method.
+|In '''Compile time polymorphism''', '''class''' can have more than one '''method'''.
 |-
@@ Line 355: / Line 355: @@
 |-
 | 10:11
-| In this tutorial we learnt:
+| In this tutorial, we learnt:
-What is '''Polymorphism''' in Java?
+* '''Run-time polymorphism'''
 '''Run-time polymorphism'''
-'''Virtual Method Invocation''' and
+* '''Virtual Method Invocation''' and
 '''Compile-time polymorphism'''
 |-
 | 10:23
 | As an assignment,
 Override methods for '''Vehicle''' and '''Bike class''' which we used in previous tutorials.
@@ Line 374: / Line 375: @@
 |-
 | 10:40
-| The Spoken Tutorial Project Team conducts workshops and gives certificates to those who pass an online test.For more details, please write to us.
+| The Spoken Tutorial Project Team:
 |-
 | 10:51
-| Spoken Tutorial Project is supported by NMEICT, MHRD, Government of India.More information on this Mission is available at this link.
+| Spoken Tutorial Project is supported by NMEICT, MHRD, Government of India. More information on this mission is available at this link.
 |-
 | 11:03
-| Thats it for the tutorial. This is Trupti Kini from IIT Bombay signing off. Thank you for joining.
+| Thats it for the tutorial. This is Trupti Kini from '''IIT Bombay''', signing off. Thank you for joining.
 |}

@@ Line 6: / Line 6: @@
 |-
 | 00:01
-| Welcome to the '''spoken-tutorial '''on '''Polymorphism in Java.'''
+| Welcome to the '''spoken-tutorial '''on '''Polymorphism''' in Java.
 |-
 | 00:06
-| In this tutorial we will learn :
+| In this tutorial, we will learn about:
-About '''Polymorphism''' in Java
-'''Run-time polymorphism'''
+* '''Polymorphism''' in Java
 '''Virtual Method Invocation''' and
-'''Compile-time polymorphism'''
+* '''Run-time polymorphism'''
 |-
 | 00:19
-| Here we are using
+| Here we are using:
 '''Ubuntu Linux Version 12.04'''
-'''JDK Version 1.7'''  and
+* '''Ubuntu Linux Version 12.04'''
 '''Eclipse 4.3.1'''
 |-
 | 00:31
-| To follow this tutorial, you must have basic knowledge of '''Java and Eclipse IDE.'''
+| To follow this tutorial, you must have basic knowledge of '''Java''' and '''Eclipse IDE'''.
 |-
 | 00:37
-| You must have knowledge of '''Subclassing '''& '''Method overriding and overloading'''
+| You must have knowledge of '''Subclassing '''& '''Method overriding''' and '''overloading'''.
 |-
@@ Line 37: / Line 44: @@
 |-
 | 00:48
-| '''Polymorphism''' is an ability of an object to take on many forms.
+| '''Polymorphism''' is an ability of an '''object''' to take on many forms.
 |-
@@ Line 45: / Line 52: @@
 . Reduction of complexity &
-. Code re-usability
+. Code re-usability.
 |-
@@ Line 53: / Line 60: @@
 |-
 | 01:11
-| '''Compile-time polymorphism''' is essentially refered as '''Method overloading'''.  It is also called '''Static Binding'''.
+| '''Compile-time polymorphism''' is essentially referred as '''Method overloading'''.  It is also called '''Static Binding'''.
 |-
@@ Line 73: / Line 80: @@
 |-
 | 01:49
-| '''Employee '''class is the parent class.
+| '''Employee '''class is the '''parent class'''.
 |-
 | 01:52
-|  '''Manager '''class is the subclass.
+|  '''Manager '''class is the '''subclass'''.
 |-
@@ Line 85: / Line 92: @@
 |-
 | 02:01
-| '''Manager '''class method '''getDetails()''' overrides the '''Employee '''class method '''getDetails().'''
+| '''Manager '''class method '''getDetails()''' '''override'''s the '''Employee '''class method '''getDetails().'''
 |-
@@ Line 93: / Line 100: @@
 |-
 |  02:16
-|  In order to print the details, type '''system.out.println Details of Manager Class.'''
+|  In order to print the details, type: '''system.out.println Details of Manager Class.'''
 |-
 | 02:28
-| '''Save '''and run the program. So we can see '''department''' variable value in the output.
+| '''Save '''and '''run''' the program. So, we can see '''department''' variable value in the output.
 |-