PoojaMoolya at 12:03, 24 April 2019

2019-04-24T12:03:22Z

Sandhya.np14 at 09:12, 18 May 2017

2017-05-18T09:12:01Z

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Pratik kamble at 13:58, 20 February 2017

2017-02-20T13:58:19Z

PoojaMoolya at 09:47, 13 January 2017

2017-01-13T09:47:43Z

PoojaMoolya at 09:46, 13 January 2017

2017-01-13T09:46:54Z

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PoojaMoolya: Created page with " {| Border=1 | '''Time''' | '''Narration''' |- | 00:01 | Welcome to the Spoken Tutorial on''' Abstract Classes.''' |- | 00:05 | In thi..."

2016-08-12T08:40:49Z

Created page with " {| Border=1 | <center>'''Time'''</center> | <center>'''Narration'''</center> |- | 00:01 | Welcome to the Spoken Tutorial on''' Abstract Classes.''' |- | 00:05 | In thi..."

New page

{| Border=1
| <center>'''Time'''</center>
| <center>'''Narration'''</center>

|-
| 00:01
| Welcome to the Spoken Tutorial on''' Abstract Classes.'''

|-
| 00:05
| In this tutorial we will learn about: '''Abstract Methods '''and''' Concrete Methods'''

|-
| 00:12
| '''Abstract Classes '''and''' Concrete Classes '''and

|-
| 00:15
| How to use '''Abstract Classes'''

|-
| 00:18
| For this tutorial, I am using
* '''Ubuntu 12.04'''
* '''JDK 1.7 '''and
* '''Eclipse''' '''4.3.1'''

|-
| 00:28
| To follow this tutorial, you should have knowledge of basics of''' Java''' and''' Eclipse IDE.'''

|-
| 00:36
| You should also have the knowledge of''' subclassing '''in''' Java.''' If not, for relevant''' Java '''tutorials, please visit the link shown.

|-
| 00:46
| First we will see about '''Abstract Method'''.

|-
| 00:50
| An '''Abstract method''' is a''' method''' that is declared without implementation.

|-
| 00:55
| It is declared using''' abstract '''keyword. There should not be opening and closing parenthesis for this '''method'''.

|-
| 01:04
| The''' method showDetails()''' illustrated here, is an example of''' abstract method'''.

|-
| 01:10
| Note that this '''method''' is declared using the''' abstract '''keyword, with no current implementation.

|-
| 01:18
| Next we will see about '''concrete method'''.

|-
| 01:21
| A '''Concrete method''' is completely implemented within the curly brackets.

|-
| 01:27
| This method''' showBasicDetails()''' illustrated here is an example of '''concrete method'''.

|-
| 01:35
| Observe that this '''method''' is implemented completely.

|-
| 01:39
| Now we will learn about '''abstract class''' with an example.

|-
| 01:44
| An''' abstract class''' usually contains at least one''' abstract method'''.

|-
| 01:49
| '''Abstract methods '''can be added only to '''abstract classes.'''

|-
| 01:54
| The '''class Person''' illustrated here is an''' abstract class.'''

|-
| 01:59
| It contains an''' abstract method''' called''' showDetails()'''.

|-
| 02:04
| It can also contain '''variables''' and other '''concrete methods.'''

|-
| 02:09
| The figure here represents an '''inheritance relation'''. Here, the''' Person class''' is an''' abstract class.'''

|-
| 02:18
| The''' Employee class''' and the '''Student class''' are '''subclasses''' of the''' Person class'''.

|-
| 02:24
| These '''subclasses''' can provide their own different implementations.

|-
| 02:29
| These are done by''' showDetails( ) method''' present in the''' Person class.'''

|-
| 02:35
| For example: '''ShowDetails() Method''' in the''' Employee class''' prints the '''Employee ID''' and the''' Salary''', where as '''ShowDetails() Method''' in the''' Student class''' prints the '''Student Reg No''' and the '''Grade.'''

|-
| 02:49
| A '''class''' is said to be a''' concrete class,''' if all the '''methods''' in that '''class''' are''' concrete methods'''.

|-
| 02:57
| The '''class Employee''' illustrated here, is a''' concrete class'''. All the '''methods''' inside this '''class''' including''' showDetails()''' are '''concrete'''.

|-
| 03:07
| Let us understand the usage of '''Abstract class '''with a sample program.

|-
| 03:12
| Now we will switch to''' Eclipse''' and create a new '''project''' called '''AbstractDemo'''.

|-
| 03:19
| Inside this '''project''', we will create the necessary '''classes''' to demonstrate the usage of''' Abstract class.'''

|-
| 03:27
| Now, right click on '''src''' folder and click '''new-'''> '''class'''.

|-
| 03:33
| Type the name of the '''class''' as '''Person''' and press '''Enter'''.

|-
| 03:38
| Now we will add the fields to represent the name and age of the''' Person'''.

|-
| 03:44
| Type''' String name semicolon.''' Also type''' int age semicolon.'''

|-
| 03:51
| Now click on''' source ->''' and select''' generate constructor using fields. '''

|-
| 03:58
| Delete the '''super '''keyword from the generated code.

|-
| 04:02
| The '''constructor''' can initialise the values of '''name''' and '''age '''fields.

|-
| 04:08
| We will add a''' concrete method''' to this '''class''' to print the name and age.

|-
| 04:14
| So type '''public void showBasicDetails( )''' within '''brackets''' type, '''System.out.println''' within round brackets and within quotes type''' Name colon''' plus''' name semicolon'''

|-
| 04:33
| Also type '''System.out.println''' within round brackets and within quotes''' Age colon''' plus''' age semicolon'''

|-
| 04:46
| Now we will add an '''abstract method''' to this '''class'''. So type '''public void showDetails( ) semicolon'''

|-
| 04:56
| An error comes up, since we have not yet added the''' abstract '''keyword.

|-
| 05:01
| So now, add the keyword '''abstract.'''

|-
| 05:04
| Now we can see, another error comes up. This is because, '''abstract methods''' can be added only to '''abstract classes'''.

|-
| 05:13
| So now, add the keyword''' abstract''' to the''' Person class '''to make it an''' abstract class.'''

|-
| 05:20
| Then right click on the '''default package''' and create another''' class''' called''' Employee.'''

|-
| 05:26
| Now to make this a '''subclass''' of '''Person class, '''type''' extends Person'''.

|-
| 05:34
| Now we can see an error comes up in the '''Eclipse IDE.'''

|-
| 05:38
| It indicates that, we should provide an implementation to the '''abstract method showDetails( )'''.
We will do it a little later.

|-
| 05:48
| Now create two fields to represent the '''employee id''' and '''employee salary'''.

|-
| 05:54
| So type ''' String empid semicolon''' and''' int salary semicolon'''

|-
| 06:01
| Now click on '''source'''-> and then select''' generate constructor using fields.'''

|-
| 06:08
| This '''constructor''' can initialise the values of '''name, age, empid '''and''' salary'''.

|-
| 06:15
| Let us now define the''' showDetails method'''. So type''' public void showDetails( )'''

|-
| 06:23
| Inside this '''method''', we need to print the employee details.

|-
| 06:27
| So type '''System.out.println''' within quotes''' Emp id colon''' plus''' empid semicolon'''

|-
| 06:38
| '''System.out.println''' within quotes''' Salary colon''' plus''' salary semicolon'''

|-
| 06:47
| Note that the error disappears, once the '''showDetails() method''' is implemented.

|-
| 06:54
| Next we will see a '''Student class''' of the '''project'''.

|-
| 06:57
| I have already created a '''subclass''' called''' Student'''.

|-
| 07:02
| There are two fields in the '''Student class, regno (register number) ''' and''' grade''' which represent '''student reg. no (register number)''' and '''grade'''.

|-
| 07:11
| A '''constructor''' is also created inside this '''class'''. This '''constructor''' can be used to initialize the values for''' name, age, register number '''and''' grade.'''

|-
| 07:24
| The''' showDetails method''' is also implemented in this '''class'''. It prints the values of''' Student Reg. Number''' and''' grade'''

|-
| 07:34
| Now note that the''' Employee class''' has its own implementation of''' showDetails().'''

|-
| 07:42
| And the''' Student class''' has its own implementation of''' showDetails().'''

|-
| 07:48
| Now right click on the '''default package.''' Click on '''new'''-> '''class''' and then type name as''' Demo.'''

|-
| 07:57
| Inside this '''class''', we will have the '''main method''', So type '''main''' and then press '''Ctrl space''' to generate the''' main method.'''

|-
| 08:08
| Now let us try to instantiate the''' Person class''' by typing '''Person p equals new Person.'''

|-
| 08:16
| Within brackets and double quotes, type '''John''' and put a '''semicolon'''.

|-
| 08:23
| Now we can see an error. This is because the''' Person class''' is '''abstract''' and it cannot be instantiated. Let's remove this line.

|-
| 08:34
| Type the following code as displayed on the screen.

|-
| 08:38
| Now let us instantiate the''' Person class''' using the''' Employee class''' as '''Person p1 equals new Employee.'''

|-
| 08:48
| In the first line, we are passing the values of different '''arguments'''.

*'''John''' is passed as '''Employee name''',

|-
| 08:57
| '''40''' as the value of '''age. E267''' as the value of '''Employee ID''' and

|-
| 09:04
| '''10000''' as the value of '''Employee salary.'''

|-
| 09:07
| Now we can invoke the '''concrete method''' in the '''Person class''' as '''p1.showBasicDetails()'''

|-
| 09:16
| We can also call the''' showDetails() method''' using the '''object p1''' as '''p1.showDetails()'''

|-
| 09:24
| Similarly, instantiate the''' Person class''' using the''' Student class'''. This is represented as '''Person p2 equals new Student.'''

|-
| 09:35
| Now we are passing the values of different '''arguments'''.

'''Hari''' is passed as the value of''' student name''',

|-
| 09:44
| '''20''' as the value of '''age'''.

|-
| 09:47
| '''12005''' as the value of''' student Reg No.''' and '''A''' as the value of '''grade'''.

|-
| 09:55
| Now we can call the''' showBasicDetails() method '''using the '''object p2''' as '''p2.showBasicDetails()'''

|-
| 10:04
| We can also invoke the''' showDetails() method''' using the '''object p2''' as '''p2.showDetails()'''

|-
| 10:13
| Now let us run this '''Demo''' program. So right click on the '''class Demo''' and then select '''Run as''' ->''' Java Application'''

|-
| 10:23
| We can see the output with the basic employee details like''' name '''and''' age.'''

|-
| 10:29
| These are printed by '''showBasicDetails() method.'''

|-
| 10:33
| Other Employee details like''' employee ID '''and '''salary '''are printed by the''' showDetails() method'''.

|-
| 10:41
| Similarly, the basic student details like '''name''' and '''age''' are printed by''' showBasicDetails() method.'''

|-
| 10:50
| Other details of the student like '''Student register no '''and '''grade''' are printed by the''' showDetails() method'''.

|-
| 10:59
| This brings us to the end of this tutorial. Let us summarize.

|-
| 11:05
| In this tutorial we have learnt about

* '''Abstract Methods '''and''' Concrete Methods'''
* '''Abstract Classes '''and''' Concrete Classes '''and
* How to create and use''' Abstract Classes'''

|-
| 11:19
| As an assignment- Create an '''abstract class Vehicle''' which contains an '''abstract method run()'''

|-
| 11:27
| Create a '''subclass Car''' which extends the '''Vehicle class''' and implements the '''run method''' that prints '''“Car is running on 4 wheels”'''

|-
| 11:37
| Also create a'''subclass Bike''' which again extends the '''Vehicle class''' and implements the '''run method''' that prints '''“Bike is running on 2 wheels”'''

|-
| 11:48
| Also create a '''Demo class '''containing the''' main method''' to verify the results.

|-
| 11:54
| The video at the following link summarizes the''' '''Spoken Tutorial Project. Please download and watch it.

|-
| 12:02
| The Spoken Tutorial Project Team

* Conducts workshops using spoken tutorials
* Gives certificates on passing the online tests

|-
| 12:11
| For more details, please write to us.

|-
| 12:15
| Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this Mission is available at the link shown.

|-
| 12:26
| This script has been contributed by: Dept. of Information Technology, Amal Jyothi College of Engineering.

This is Priya from IIT Bombay signing off. Thank you for joining.

|}

@@ Line 9: / Line 9: @@
 |-
 |00:05
-| In this tutorial, we will learn about: * '''Abstract Methods '''and''' Concrete Methods'''
+| In this tutorial, we will learn about:  '''Abstract Methods '''and''' Concrete Methods'''
 |-
 | 00:12
-|* '''Abstract Classes '''and''' Concrete Classes '''and
+| '''Abstract Classes '''and''' Concrete Classes '''and
 |-
 | 00:16
-|* How to use '''Abstract Classes'''.
+|How to use '''Abstract Classes'''.
 |-
@@ Line 23: / Line 23: @@
 | For this tutorial, I am using:
-* '''Ubuntu 12.04'''
+'''Ubuntu 12.04'''
-* '''JDK 1.7 '''and
+'''JDK 1.7 '''and
-* '''Eclipse''' '''4.3.1'''
+'''Eclipse''' '''4.3.1'''
 |-
@@ Line 383: / Line 383: @@
 |-
 | 09:07
-| In this tutorial, we have learnt about:
+| In this tutorial, we have learnt about: '''Abstract Methods '''and''' Concrete Methods'''
-* '''Abstract Methods '''and''' Concrete Methods'''
 |-
 |09:14
+| '''Abstract Classes '''and''' Concrete Classes '''and  How to create and use''' Abstract Classes'''.
-* '''Abstract Classes '''and''' Concrete Classes '''and
-* How to create and use''' Abstract Classes'''.
 |-
@@ Line 414: / Line 411: @@
 |-
 | 10:03
-| The Spoken Tutorial Project Team: * Conducts workshops using spoken tutorials and
+| The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials and
 |-
 |10:09
-|* Gives certificates on passing the online tests.
+|Gives certificates on passing the online tests.
 |-