Java/C3/Using-final-keyword/English-timed - Revision history

Sandhya.np14 at 16:19, 18 September 2018

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Sandhya.np14 at 16:17, 18 September 2018

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Sandhya.np14 at 10:33, 17 September 2018

2018-09-17T10:33:32Z

Jyotisolanki at 07:20, 18 October 2017

2017-10-18T07:20:42Z

Sandhya.np14 at 11:21, 17 May 2017

2017-05-17T11:21:34Z

Sandhya.np14 at 11:20, 17 May 2017

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Sandhya.np14 at 09:51, 17 May 2017

2017-05-17T09:51:23Z

Pratik kamble at 14:01, 20 February 2017

2017-02-20T14:01:35Z

PoojaMoolya: Created page with "{| Border=1 | '''Time''' | '''Narration''' |- | 00:01 | Welcome to the spoken-tutorial on '''Using final keyword.''' |- | 00:05 | In this tutorial we will learn abo..."

2016-08-12T08:59:00Z

Created page with "{| Border=1 | '''Time''' | '''Narration''' |- | 00:01 | Welcome to the spoken-tutorial on '''Using final keyword.''' |- | 00:05 | In this tutorial we will learn abo..."

New page

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

|-
| 00:01
| Welcome to the spoken-tutorial on '''Using final keyword.'''

|-
| 00:05
| In this tutorial we will learn about : The final keyword and when to invoke it.

|-
| 00:11
| We will also learn about -

* '''final variables,'''
* '''final methods,'''
* '''final classes'''

|-
| 00:18
| To record this tutorial, I am using

* '''Ubuntu Linux''' version 12.04
* '''JDK''' 1.7
* '''Eclipse''' 4.3.1

|-
| 00:30
| To follow this tutorial, you must have, Basic knowledge of '''Java''' and '''Eclipse IDE.'''

|-
| 00:36
| You must have knowledge of '''Subclassing''' and '''Method overriding'''.

|-
| 00:41
| If not, for relevant '''Java''' tutorials, please visit our website.

|-
| 00:46
| First of all, we will learn what '''final''' '''keyword''' is

|-
| 00:50
| '''final''' is a '''keyword''' or '''reserved''' word in '''Java'''.

|-
| 00:55
| It can be applied to '''variables, methods '''or '''classes.'''

|-
| 01:01
| Now, let us learn what '''final''' '''variable''' is.

|-
| 01:05
| '''final variable''' is a variable whose value cannot be changed. That is, it will be a '''constant'''.

|-
| 01:13
| I am switching to '''Eclipse IDE '''now. I had already created a project named '''MyProject''' in the previous tutorial.

|-
| 01:22
| So we will directly go to the '''Employee class''' of the project.

|-
| 01:26
| Come to the variable '''name.'''

|-
| 01:30
| Add '''final keyword''' before the variable '''name'''. We have made the variable '''name '''as '''final.'''

|-
| 01:40
| We will initialize the variable '''name '''with value '''sneha.'''

|-
| 01:45
| We will '''Save''' and '''Run''' the program.

|-
| 01:48
| We get compilation error. '''The final field Employee.name cannot be assigned'''

|-
| 01:55
| This is because here the '''final variable''' name is already declared and initialised.

|-
| 02:05
| We can initialize a final variable only once.

|-
| 02:08
| So we will comment the method '''setName''' which modifies the variable '''name'''.

|-
| 02:14
| Save the '''class'''.

|-
| 02:16
| Now, come to '''TestEmployee class'''.

|-
| 02:19
| Come to the '''main method''' and comment the line '''manager.setName("Nikkita Dinesh");'''

|-
| 02:26
| We commented this line as it was instance of method '''setName.'''

|-
| 02:31
| We have already commented '''setName '''method in '''Employee '''class.

|-
| 02:35
| Now let us '''Save''' the class and '''Run''' the program.

|-
| 02:38
| Great!!!

We got the output,

'''Name: Sneha'''

'''Email: abc@gmail.com'''

'''Manager of: Accounts'''

|-
| 02:47
| We got this output as we already initialized variables with these values in

'''TestEmployee class''' and '''Employee class'''.

|-
| 02:58
| Now come to the '''final variable''' '''name''' in''' Employee '''class.

|-
| 03:02
| Remove the initialization of '''final variable name.''' That is remove “'''sneha”.'''

|-
| 03:08
| Uncomment the method '''setName'''.

|-
| 03:12
| '''Save''' and '''Run''' the program.

|-
| 03:14
| We get the error, '''The final field Employee.name cannot be assigned'''

|-
| 03:20
| This is because, if the '''final''' variable is not initialised, then only '''constructor''' can initialize it.

|-
| 03:28
| That is, it cannot be modified anywhere else in the program.

|-
| 03:33
| For that, let’s create a '''constructor '''in the '''Employee class.''' We have already learnt what a '''constructor '''is earlier.

|-
| 03:43
| We know that '''constructor''' has the same name as '''class''' name.

|-
| 03:47
| So we will type '''Employee, parentheses, open and close curly brackets''' and inside the curly brackets, lets initialize the variable '''name''' with value '''sneha semicolon .'''

|-
| 04:08
| Comment the '''method setName'''.

|-
| 04:12
| '''Save''' and '''Run''' the program.

|-
| 04:15
| We got the desired output.

|-
| 04:17
| '''final '''variable is successfully initialized in a '''constructor'''.

|-
| 04:22
| Now we will learn about '''final static variables.'''

|-
| 04:26
| Come to the final variable in '''Employee class'''.

|-
| 04:30
| Add '''static''' keyword before '''final keyword'''. We have made the '''final variable''' as '''static'''.

|-
| 04:38
| '''Save '''and '''Run''' the program.

|-
| 04:40
| We get error. '''The final field Employee.name cannot be assigned'''

|-
| 04:46
| This is because '''static final variables '''cannot be initialized in the '''constructor.'''

|-
| 04:53
| They must be assigned a value with their declaration. Or they must be declared in a '''static block'''.

|-
| 05:01
| '''static''' variables are shared among all the objects of a '''class'''.

|-
| 05:06
| Creating a new '''object''' would change the '''static variable'''. This is not allowed if the '''static variable''' is '''final.'''

|-
| 05:14
| Switch back to '''Eclipse IDE.'''

|-
| 05:17
| So now we will create a '''static block.'''

|-
| 05:20
| For that, in the '''Employee '''class, come to the '''constructor. '''we created.

|-
| 05:26
| Here instead of '''Employee parenthesis , '''we will type '''static'''. We have created a '''static block'''.

|-
| 05:35
| Now we will '''Save''' and '''Run''' the program.

|-
| 05:38
| We got the desired output. We have successfully initialized '''static final''' variable.

|-
| 05:46
| Now let’s use '''final''' variable as a parameter to the '''method'''.

|-
| 05:52
| Come to the method '''setEmail.''' in '''Employee''' class.

|-
| 05:55
| Add '''final''' keyword before '''String newEmail'''. We have made the parameter as '''final'''.

|-
| 06:03
| '''Save''' and '''Run''' the program.

|-
| 06:06
| We got the desired output.

|-
| 06:09
| Now, come to the method''' setEmail'''.

Inside the '''method''' we will type, '''newEmail is equal to abc@gmail.com semicolon'''

|-
| 06:28
| We have modified the '''final''' variable '''newEmail'''.

|-
| 06:32
| Once again we will '''Save''' & '''Run '''the program.

|-
| 06:35
| We get error. '''The final local variable newEmail cannot be assigned.'''

|-
| 06:42
| This is because '''final''' variable as parameter to a '''method '''cannot be modified by that '''method.'''

|-
| 06:50
| So lets remove the variable modification.

|-
| 06:54
| Now we will learn about '''final method'''. Come to the '''method getDetails''' in '''employee class'''.

|-
| 07:01
| Add '''final '''keyword before '''method getDetails'''. We have made the method as '''final'''.

|-
| 07:08
| '''Save '''and '''Run''' the program.

|-
| 07:10
| We get error, '''class Manager overrides final method getDetails.()'''

|-
| 07:16
| Come to the '''method getDetails()''' in '''Manager''' class.

|-
| 07:21
| This is because if you make any '''method''' as '''final''', you cannot '''override''' it.

|-
| 07:29
| '''Manager class method getDetails''' overrides '''getDetails method''' in '''Employee class. '''

|-
| 07:36
| What if '''final method''' is '''private'''?

|-
| 07:39
| '''private methods''' are not inherited by the '''child class.'''

|-
| 07:43
| So we can add a method '''getDetails() '''in the '''child class'''. You can try this as an assignment.

|-
| 07:51
| Switch back to '''Eclipse IDE.'''

|-
| 07:54
| In '''Employee''' class, remove '''final''' keyword before '''method getDetails'''.

|-
| 08:03
| Remove '''static''' keyword before '''final''' variable name.

|-
| 08:10
| Now, we will learn whether '''constructor''' can me declared as''' final '''or not.

|-
| 08:15
| For that we will again create a '''constructor'''. So instead of '''static''' we will type, '''Employee parentheses'''.

|-
| 08:26
| Add '''final '''keyword before the '''constructor'''.

|-
| 08:31
| '''Save''' and '''run''' the program.

|-
| 08:36
| We get error '''Illegal modifier for the constructor in type Employee'''

|-
| 08:42
| This is because, '''constructor''' cannot be '''final''' since '''constructors''' cannot not be inherited.

|-
| 08:50
| We will remove the '''final''' keyword before the '''constructor'''.

|-
| 08:54
| Now, we will learn about '''final class.'''

|-
| 08:57
| Add '''final''' '''keyword''' before the '''class Employee''' to make it '''final'''.

|-
| 09:03
| '''Save''' and '''Run''' the program.

|-
| 09:06
| We get error, '''The method setEmail is undefined for the type Manager'''

|-
| 09:12
| To know the actual error, lets come to '''TestEmployee '''class and comment the lines.

|-
| 09:21
| '''manager.setEmail("abc@gmail.com"); manager.setDepartment("Accounts"); '''

|-
| 09:28
| '''Save''' the class and '''run''' the program

|-
| 09:31
| The actual error is '''The type manager cannot subclass the final class Employee.'''

|-
| 09:40
| Here '''Manager class''' extends '''Employee class.'''

|-
| 09:45
| So let's come back to''' Employee''' class and remove the '''final '''keyword. Save the class.

|-
| 09:54
| Come to the''' TestEmployee''' class. Uncomment the lines '''manager.setEmail("abc@gmail.com"); manager.setDepartment("Accounts"); '''

|-
| 10:06
| '''Save''' the class and '''run''' the program.

|-
| 10:09
| We got the desired output.

|-
| 10:12
| Now let's summarize.

In this tutorial we learnt:

* When to invoke final keyword.
* What are:
** '''final variables,'''
** '''final methods '''and
** '''final classes'''

|-
| 10:27
| As an assignment,

Repeat the steps of '''Using final keyword '''tutorial for the '''Bike''' and '''Vehicle class.''' which we used in the previous tutorial.

|-
| 10:37
| Write down the '''classes''' in '''Java''' that are '''final classes. '''

|-
| 10:41
| Watch the video available at the following link. It summarizes the Spoken Tutorial project

|-
| 10:47
| The Spoken Tutorial Project Team

* Conducts workshops
* Gives certificates to those who pass an online test
* For more details, please write to us

|-
| 10:56
| Spoken Tutorial Project is supported by the National Mission on Education through ICT, MHRD, Government of India.

That's it for this tutorial. This is Trupti Kini from '''IIT Bombay'''. Thank you very much for watching.

|}

@@ Line 81: / Line 81: @@
 |-
 |  01:55
-|  This is because here the '''final variable''' name is already declared and initialised.
+|  This is because here the '''final variable 'name'''' is already declared and initialized.
 |-

@@ Line 13: / Line 13: @@
 |-
 | 00:11
-|  We will also learn about -
+|  We will also learn about -   '''final variables''' , '''final methods''' , '''final classes'''.
-−
-* '''final variables'''
-−
-* '''final methods'''
-−
-* '''final classes'''.
 |-
 | 00:18
-|  To record this tutorial, I am using:
+|  To record this tutorial, I am using:   '''Ubuntu Linux''' version 12.04 , '''JDK''' 1.7 , '''Eclipse''' 4.3.1
-* '''Ubuntu Linux''' version 12.04
-−
-* '''JDK''' 1.7
-−
-* '''Eclipse''' 4.3.1
 |-
@@ Line 128: / Line 117: @@
 |-
 |  02:38
-|  Great!!! We got the output,
+|  Great!!! We got the output,  '''Name: Sneha'''  ,'''Email: abc@gmail.com'''  '''Manager of: Accounts''' .
-−
 '''Name: Sneha'''
-−
 '''Email: abc@gmail.com'''
-−
 '''Manager of: Accounts'''
 |-
 |  02:47
-|  We got this output as we already initialized variables with these values in
+|  We got this output as we already initialized variables with these values in  '''TestEmployee class''' and '''Employee class'''.
-−
 '''TestEmployee class''' and '''Employee class'''.
 |-
@@ Line 280: / Line 261: @@
 |-
 | 06:09
-|  Now, come to the method''' setEmail'''.
+|  Now, come to the method''' setEmail'''.  Inside the '''method''', we will type: '''newEmail is equal to abc@gmail.com''' semicolon
-−
 Inside the '''method''', we will type: '''newEmail is equal to abc@gmail.com''' semicolon
 |-
@@ Line 438: / Line 417: @@
 |-
 | 10:12
-|  Now let's summarize. In this tutorial, we learnt:
+|  Now let's summarize. In this tutorial, we learnt:  When to invoke final keyword , What are '''final variables, final methods '''and '''final classes'''.
-−
-* When to invoke final keyword
-−
-* What are '''final variables, final methods '''and '''final classes'''.
 |-
 | 10:27
-|  As an assignment,
+|  As an assignment, Repeat the steps of '''Using final keyword '''tutorial for the '''Bike''' and '''Vehicle''' class which we used in the previous tutorial.
-−
 Repeat the steps of '''Using final keyword '''tutorial for the '''Bike''' and '''Vehicle''' class which we used in the previous tutorial.
 |-
@@ Line 460: / Line 433: @@
 |-
 |  10:47
-|  The Spoken Tutorial Project Team:
+|  The Spoken Tutorial Project Team: Conducts workshops ,Gives certificates to those who pass an online test. For more details, please write to us.
-* Conducts workshops
-* Gives certificates to those who pass an online test.
 For more details, please write to us.
 |-
 |  10:56
-|Spoken Tutorial Project is supported by the National Mission on Education through ICT, MHRD, Government of India.
+|Spoken Tutorial Project is supported by the National Mission on Education through ICT, MHRD, Government of India.That's it for this tutorial. This is Trupti Kini from '''IIT Bombay'''. Thank you very much for watching.
 That's it for this tutorial. This is Trupti Kini from '''IIT Bombay'''. Thank you very much for watching.
 |}

@@ Line 337: / Line 337: @@
 |-
 |  08:10
-|  Now, we will learn whether '''constructor''' can me declared as''' final '''or not.
+|  Now, we will learn whether '''constructor''' can be declared as''' final '''or not.
 |-

@@ Line 333: / Line 333: @@
 |-
 | 08:03
-|  Remove '''static''' keyword before '''final''' variable name.
+|  Remove '''static''' keyword before '''final''' variable '''name'''.
 |-

@@ Line 5: / Line 5: @@
 |-
 |  00:01
-|  Welcome to the spoken-tutorial on '''Using final keyword.'''
+|  Welcome to the '''spoken-tutorial''' on '''Using final keyword.'''
 |-
 |  00:05
-|  In this tutorial we will learn about : The final keyword and when to invoke it.
+|  In this tutorial, we will learn about the '''final''' keyword and when to invoke it.
 |-
 | 00:11
 |  We will also learn about -
-'''final variables,'''
-'''final methods,'''
+* '''final variables'''
 '''final classes'''
 |-
 | 00:18
-|  To record this tutorial, I am using
+|  To record this tutorial, I am using:
-'''Ubuntu Linux''' version 12.04
+* '''Ubuntu Linux''' version 12.04
 '''JDK''' 1.7
-'''Eclipse''' 4.3.1
+* '''JDK''' 1.7
 |-
 |  00:30
-|  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.'''
 |-
@@ Line 39: / Line 44: @@
 |-
 | 00:46
-|  First of all, we will learn what '''final''' '''keyword''' is
+|  First of all, we will learn what '''final''' '''keyword''' is.
 |-
 | 00:50
-|   '''final''' is a '''keyword''' or '''reserved''' word in '''Java'''.
+|   '''final''' is a '''keyword''' or reserved word in '''Java'''.
 |-
@@ Line 51: / Line 56: @@
 |-
 |  01:01
-|  Now, let us learn what '''final''' '''variable''' is.
+|  Now, let us learn what '''final''' variable is.
 |-