Java/C3/Static-Variables/English-timed - Revision history

Sandhya.np14 at 09:04, 5 December 2019

2019-12-05T09:04:00Z

Sandhya.np14 at 09:03, 5 December 2019

2019-12-05T09:03:30Z

Sandhya.np14 at 09:01, 5 December 2019

2019-12-05T09:01:33Z

PoojaMoolya at 12:56, 25 April 2019

2019-04-25T12:56:43Z

Sandhya.np14 at 06:14, 19 May 2017

2017-05-19T06:14:35Z

Sandhya.np14 at 05:59, 19 May 2017

2017-05-19T05:59:51Z

Pratik kamble at 13:55, 20 February 2017

2017-02-20T13:55:58Z

PoojaMoolya at 11:53, 13 January 2017

2017-01-13T11:53:50Z

Show changes

PoojaMoolya: Created page with " {| border=1 | '''Time''' | '''Narration''' |- | 00:01 | Welcome to the Spoken Tutorial on '''Static Variables.''' |- |00:05 | In this tuto..."

2016-08-12T08:54:46Z

Created page with " {| border=1 | <center>'''Time'''</center> | <center>'''Narration'''</center> |- | 00:01 | Welcome to the Spoken Tutorial on '''Static Variables.''' |- |00:05 | In this tuto..."

New page

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

|-
| 00:01
| Welcome to the Spoken Tutorial on '''Static Variables.'''

|-
|00:05
| In this tutorial we will learn about:

* What are''' static variables'''
* Creating''' static variables '''and
* How to''' '''use''' static variables'''

|-
|00:17
| Here we are using

* '''Ubuntu 12.04'''
* '''JDK 1.7 '''and
* '''Eclipse 4.3.1'''

|-
| 00:27
| To follow this tutorial, you must have knowledge of basics of''' Java''' and''' Eclipse IDE.'''

|-
| 00:35
|You should also have the knowledge of''' classes, objects '''and''' instance variables''' in''' Java.'''

|-
| 00:43
|If not, for relevant''' Java '''tutorials, please visit the link shown.

|-
| 00:49
| A''' static variable''' is a variable which is associated with the entire''' class.'''

|-
| 00:55
|It is also called a '''class variable.''' It is declared using the''' static keyword.'''

|-
| 01:02
| We have seen about static variable briefly in the earlier tutorial.

|-
| 01:08
|In this tutorial we will see it in detail. Let us illustrate the usage of''' static variables''' with an example.

|-
| 01:16
|Consider a''' class''' created to represent student enrollments in an organization.

|-
| 01:23
|This class contains the '''Name, Id , Branch''' and''' Total Count''' of students enrolled.

|-
| 01:30
|Now let us visualize what happens when student enrollments are done.

|-
| 01:36
|By default, '''Total Count''' is 0. The''' Name''' of the first student is '''ADIL.''' '''Id''' is''' IT101. Branch''' is''' IT.'''

|-
| 01:48
|Now the''' Total Count''' is updated as 1.

|-
| 01:52
|Similarly when the second student''' AMAL '''gets enrolled, '''Total Count''' is updated to 2.

|-
| 01:59
|When the third student''' CAROL''' gets enrolled,''' Total Count''' is updated to 3.

|-
| 02:06
|Now we can identify that the variable''' Total Count''' is common to all the objects and has a single value.

|-
| 02:14
|So the variable''' Total Count''' can be represented as a''' static variable'''.

|-
| 02:20
|We can also see that the variables''' Name, Id''' and''' Branch''' have their own copies for each object.

|-
| 02:28
|Also they have specific values for each object. So these variables can be treated as''' instance variables.'''

|-
| 02:38
| Now let us explore the differences between''' instance variables''' and''' static variables.'''

|-
| 02:45
|Every object has its own copies for '''instance variables.'''

|-
| 02:50
|'''Id, Name, Branch''' are examples of instance variables.

|-
| 02:55
|'''Static variables''' in a class share a single copy with all objects in that class.

|-
| 03:02
|'''Total Count''' is an example of static variable.

|-
| 03:06
| When a class is loaded a ''' static variable''' occupies a single fixed memory location

whereas '''Instance variables''' of each object occupy separate''' '''memory locations.

|-
| 03:19
| Now let us look at the sample code representing the student enrollment class.

|-
| 03:25
|The name of the class is''' StudentEnroll.''' The instance variables are declared as''' id, name''' and''' branch.'''

|-
| 03:35
|The variable''' count''' is declared as static since it is common to the whole class.

|-
| 03:41
| Now we will switch to''' Eclipse''' and create a new project called '''StaticVariableDemo'''.

|-
| 03:48
|Inside this project we will create the necessary classes to demonstrate the usage of''' Static variables.'''

|-
|03:56
| So right click on '''src''' folder and click on '''new '''-> '''class''', and type the name of the class as''' StudentEnroll''' and Press '''Enter'''.

|-
| 04:07
|Now type the code which was shown in the earlier slide.

|-
|04:12
| Now click on''' source ->''' and select''' Generate Constructor using Fields.''' Delete the''' super''' keyword from the generated code.

|-
|04:21
| This '''constructor''' can initialize the values of the''' id, name''' and''' branch '''fields.

|-
| 04:28
|We also need to increment the value of the variable''' count''' by one every time an object is created.

|-
| 04:36
|So inside the constructor type, '''count ++ semicolon.'''

|-
|04:42
| Now we will add a''' '''method '''showData'''( ) to this class to print the values of all the variables.

|-
| 04:50
|So type''' public void showData( )''' within brackets type the following code to print the values of''' id, name, branch '''and '''total number of students enrolled'''.

|-
| 05:04
| Now right click on the '''default package''' click on '''new '''-> '''class''' and then type name as''' Demo.'''

|-
| 05:12
|Inside this class we will have the '''main''' method.

|-
| 05:16
|So type '''main''' and then press ctrl+space to generate the''' main method.'''

|-
| 05:22
| Now we need to print the Student Enrollment data.

|-
| 05:27
|We will create a few objects of''' StudentEnroll class''' to represent student enrollments.

|-
| 05:34
|So type''' '''the following code. '''StudentEnroll s1 equals new StudentEnroll'''

|-
| 05:41
|Now we can pass the values of different arguments. Within brackets type''' IT101 '''as''' id, ADIL''' as''' name '''and''' IT''' as '''branch.'''

|-
| 05:54
|Now let us invoke the''' showData''' method to print the enrollment details. So type

'''s1.showData( )'''.

|-
| 06:03
|Now run the '''Demo''' program.

|-
| 06:06
|We can see that the values of the instance variables corresponding to''' s1''' get printed.

|-
| 06:13
|Also note that the value of the number of student enrollments is 1.

|-
| 06:19
|This is because we have created only 1 object.

|-
| 06:23
|Now type the following code to create one more object''' s2.'''

|-
| 06:28
|The''' showData''' method can be called once again using''' s2.'''

|-
| 06:33
|Again run the '''Demo''' Program.

|-
| 06:36
|We can see that the values of the instance variables corresponding to''' s2''' get printed.

|-
| 06:43
|Also note that the value of''' number of student''' enrollments is updated to 2 for both''' s1''' and''' s2.'''

|-
| 06:51
|Now create one more object''' s3.'''

|-
| 06:54
|Now Let us Invoke the''' showData''' method again using''' s3.'''

|-
| 07:00
|Run the '''Demo''' Program again.

|-
| 07:02
|We can see that the values of the instance variables corresponding to''' s3''' get printed.

|-
| 07:09
|Also note that the value of''' '''number of student enrollments is now updated to 3 in all the cases.

|-
| 07:17
|Now we can understand that the value of the number of student enrollments is common to all the objects.

|-
|07:25
| Come back to slides. The''' static''' modifier, is also used along with the final modifier.

|-
| 07:33
|It is done to define a''' constant''' which is common to the entire class.

|-
| 07:38
|Conventionally, the names of such constant variables are spelled in uppercase letters.

|-
|07:44
| If the name is composed of more than one word, the words are separated by '''an underscore.'''

|-
| 07:51
|As an Example, if all the students are getting enrolled to the same organisation say''' IITB'''.

|-
| 07:59
|It can be represented by using a constant static variable say''' ORG_NAME'''.

|-
| 08:06
|Usually we declare such constants with a '''public''' visibility.

|-
|08:11

| A Static variable can be accessed directly from another class by using its own class name.

For Example: StudentEnroll.ORG_NAME;

|-
| 08:24
| Now come back to eclipse.

|-
| 08:27
|Open the '''StudentEnroll''' class and type the variable declaration as '''public static final String ORG_NAME = “IITB”;'''

|-
| 08:39
|Now go to the '''Demo class '''and type the following code

|-
| 08:45
|Here you can see that '''ORG_NAME '''is accessed by using its class name '''StudentEnroll.'''

|-
| 08:53
|Now run the '''Demo''' Program again.

|-
| 08:56
|We can see that the '''ORGANISATION''' name is getting printed as''' IITB.'''

|-
|09:01
| Let us summarize. In this tutorial we have learnt about

* What is a static variable and when it is used
* How to create and invoke the static variables

|-
| 09:15
| As an Assignment. Design a class''' CarService''' to represent a Car Service Station.

|-
| 09:22
|This class should contain variables to represent the following details.

|-
| 09:27
|'''Name''' of the Service Station. Car '''make''', '''model''' and '''reg. no''' - which are in for service.

'''No. of Cars in''' for Service.

|-
| 09:37
|Identify the instance variables and static variables.

|-
| 09:41
|Declare them using suitable keywords.

|-
| 09:45
|Define a''' constructor''' to initialize the values for Car make, model and regno.

|-
| 09:51
|Define a method''' show( )''' to print the values of all the variables.

|-
| 09:57
|Also create a''' Demo''' class containing the main method to verify the results.

i.e Create a few objects of''' CarService.'''

|-
| 10:06
|Invoke the''' show( ) '''method using these objects.

|-
| 10:10
|Also access the static variables directly using the class name.

|-
|10:15
| The video at the following link summarizes the Spoken Tutorial Project. Please download and watch it.

|-
| 10:22
| The Spoken Tutorial Project Team

• Conducts workshops using spoken tutorials and

• Gives certificates on passing the online tests.

|-
| 10:32
|For more details, please write to us.

|-
|10:35
| Spoken Tutorial Project is funded by the NMEICT, MHRD, Government of India.

|-
| 10:41
|More information on this Mission is available at the link shown.

|-
| 10:46
| This script has been contributed by:

Department of Information Technology, Amal Jyothi College of Engineering.

This is Priya from IIT Bombay signing off. Thanks for joining.

|}

@@ Line 9: / Line 9: @@
 |-
 |00:05
-|In this tutorial, we will learn about: * What are''' static variables'''
+|In this tutorial, we will learn about: What are''' static variables''',
 |-
 |00:10
-|Creating''' static variables '''and * How to use''' static variables'''.
+|creating''' static variables '''and how to use''' static variables'''.
 |-
 |00:17
-|Here, we are using: '''Ubuntu 12.04'''
+|Here, we are using: '''Ubuntu 12.04''',
-'''JDK 1.7 '''and  '''Eclipse 4.3.1'''
+'''JDK 1.7 '''and
 |-

@@ Line 123: / Line 123: @@
 |-
 | 03:04
-| Now, let us look at the code representing the '''student enrollment class'''.
+| Now, let us look at the code representing the '''student Enroll class'''.
 |-

@@ Line 13: / Line 13: @@
 |-
 |00:10
-|* Creating''' static variables '''and * How to use''' static variables'''.
+|Creating''' static variables '''and * How to use''' static variables'''.
 |-
 |00:17
-|Here, we are using:
+|Here, we are using: '''Ubuntu 12.04'''
-* '''Ubuntu 12.04'''
-* '''JDK 1.7 '''and
+'''JDK 1.7 '''and  '''Eclipse 4.3.1'''
-* '''Eclipse 4.3.1'''
 |-
@@ Line 328: / Line 327: @@
 |-
 |08:17
-|* What is a '''static variable''' and when it is used
+|What is a '''static variable''' and when it is used
 |-
 |08:21
-|* How to create and invoke the '''static variables'''.
+|How to create and invoke the '''static variables'''.
 |-
@@ Line 340: / Line 339: @@
 |-
 |08:32
-|This '''class''' should contain variables to represent the following details:
+|This '''class''' should contain variables to represent the following details: '''Name''' of the Service Station,
-* '''Name''' of the Service Station,
 |-
 |08:39
-|* Car '''make, model''' and '''register number''' - which are in for service
+| Car '''make, model''' and '''register number''' - which are in for service
 |-
 |08:44
-|* '''No. of Cars in''' for Service.
+| '''No. of Cars in''' for Service.
 |-
@@ Line 386: / Line 384: @@
 |-
 |09:32
-|The '''Spoken Tutorial Project''' Team:
+|The '''Spoken Tutorial Project''' Team: Conducts workshops using spoken tutorials and
-* Conducts workshops using spoken tutorials and
-* Gives certificates on passing the online tests.
+Gives certificates on passing the online tests.
 |-

@@ Line 228: / Line 228: @@
 |-
 |05:52
-|The''' showData method''' can be called once again using''' s2.'''
+|The''' showData''' method can be called once again using''' s2.'''
 |-
 |05:56
-|Again run the '''Demo''' Program.
+|Again '''run''' the '''Demo''' Program.
 |-
@@ Line 240: / Line 240: @@
 |-
 |06:06
-|Also note that the value of''' number of student''' enrollments is updated to 2 for both''' s1''' and''' s2.'''
+|Also, note that the value of number of student enrollments is updated to 2 for both''' s1''' and''' s2.'''
 |-
@@ Line 248: / Line 248: @@
 |-
 |06:18
-|Now let us Invoke the''' showData method''' again using''' s3.'''
+|Now let us Invoke the''' showData''' method again using''' s3.'''
 |-
 |06:23
-|Run the '''Demo''' Program again.
+|'''Run''' the '''Demo''' program again.
 |-
@@ Line 260: / Line 260: @@
 |-
 |06:32
-|Also note that the value of''' number of student''' enrollments is now updated to 3 in all the cases.
+|Also note that the value of number of student enrollments is now updated to 3 in all the cases.
 |-
@@ Line 268: / Line 268: @@
 |-
 |06:48
-|Come back to slides.
+|Come back to '''slide'''s.
 |-
@@ Line 316: / Line 316: @@
 |-
 | 08:03
-| Now run the '''Demo''' Program again.
+| Now '''run''' the '''Demo''' program again.
 |-
@@ Line 324: / Line 324: @@
 |-
 |08:11
-|Let us summarize. In this tutorial we have learnt about
+|Let us summarize. In this tutorial, we have learnt about:
 |-
 |08:17
-| What is a '''static variable''' and when it is used
+|* What is a '''static variable''' and when it is used
 |-
 |08:21
-| How to create and invoke the '''static variables'''
+|* How to create and invoke the '''static variables'''.
 |-
 |08:25
-|As an Assignment. Design a '''class CarService''' to represent a Car Service Station.
+|As an Assignment, design a '''class CarService''' to represent a car service station.
 |-
 |08:32
 |This '''class''' should contain variables to represent the following details:
-'''Name''' of the Service Station
+* '''Name''' of the Service Station,
 |-
 |08:39
-|Car '''make''', '''model''' and '''register number''' - which are in for service
+|* Car '''make, model''' and '''register number''' - which are in for service
 |-
 |08:44
-|'''No. of Cars in''' for Service
+|* '''No. of Cars in''' for Service.
 |-
 |08:47
-|Identify the '''instance variables''' and '''static variables'''
+|Identify the '''instance variables''' and '''static variables'''.
 |-
 |08:51
-|Declare them using suitable keywords
+|Declare them using suitable keywords.
 |-
 |08:55
-|Define a''' constructor''' to initialise the values for Car '''make, model''' and '''register number'''
+|Define a''' constructor''' to initialise the values for Car '''make, model''' and '''register number'''.
 |-
 |09:01
-|Define a '''method show( )''' to print the values of all the variables
+|Define a method '''show( )''' to print the values of all the variables.
 |-
 |09:07
-|Also create a''' Demo class''' containing the '''main method''' to verify the results
+|Also, create a''' Demo class''' containing the '''main''' method to verify the results
-i.e Create a few '''objects''' of''' CarService'''
+i.e create a few '''objects''' of''' CarService'''.
 |-
 |09:16
-|Invoke the''' show( ) method''' using these '''objects'''
+|Invoke the''' show( )''' method using these '''objects'''.
 |-
 |09:20
-|Also access the '''static variables''' directly using the '''class''' name.
+|Also, access the '''static variables''' directly using the '''class''' name.
 |-
@@ Line 386: / Line 386: @@
 |-
 |09:32
-|The Spoken Tutorial Project Team  Conducts workshops using spoken tutorials and Gives certificates on passing the online tests
+|The '''Spoken Tutorial Project''' Team:
 |-
@@ Line 398: / Line 400: @@
 |-
 |09:51
-|More information on this Mission is available at the link shown.
+|More information on this mission is available at the link shown.
 |-
 |09:56
-|This script has been contributed by: Department of Information Technology, Amal Jyothi College of Engineering
+|This script has been contributed by: Department of Information Technology, Amal Jyothi College of Engineering.
 |-
 |10:03
-|This is Priya from IIT Bombay signing off. Thanks for joining.
+|This is Priya from '''IIT Bombay''', signing off. Thanks for joining.
 |}

@@ Line 5: / Line 5: @@
 |-
 |00:01
-|Welcome to the Spoken Tutorial on '''Static Variables.'''
+|Welcome to the '''Spoken Tutorial''' on '''Static Variables.'''
 |-
 |00:05
-|In this tutorial we will learn about: What are''' static variables'''
+|In this tutorial, we will learn about: * What are''' static variables'''
 |-
 |00:10
-| Creating''' static variables '''and  How to use''' static variables'''
+|* Creating''' static variables '''and * How to use''' static variables'''.
 |-
 |00:17
-|Here we are using  '''Ubuntu 12.04''',  '''JDK 1.7 '''and  '''Eclipse 4.3.1'''
+|Here, we are using:
 |-
@@ Line 25: / Line 28: @@
 |-
 |00:35
-|You should also have the knowledge of''' classes, objects ''' and''' instance variables''' in''' Java.'''
+|You should also have the knowledge of''' classes, objects ''' and''' instance variables''' in Java.
 |-
 |00:42
-|If not, for relevant''' Java '''tutorials, please visit the link shown.
+|If not, for relevant Java tutorials, please visit the link shown.
 |-
@@ Line 41: / Line 44: @@
 |-
 |00:58
-|It is declared using the''' static keyword.'''
+|It is declared using the''' static''' keyword.
 |-
@@ Line 49: / Line 52: @@
 |-
 |01:08
-|In this tutorial we will see it in detail.
+|In this tutorial, we will see it in detail.
 |-
 |01:11
-| Now we will switch to''' Eclipse''' and create a new '''project''' called '''StaticVariableDemo'''.
+| Now, we will switch to''' Eclipse''' and create a new '''project''' called '''StaticVariableDemo'''.
 |-
 |01:18
-|Inside this '''project''' we will create the necessary classes to demonstrate the usage of''' Static variables.'''
+|Inside this '''project''', we will create the necessary classes to demonstrate the usage of''' Static variables.'''
 |-
 | 01:26
-| So right click on '''src''' folder and click '''New '''-> '''Class''', and type the name of the class as''' StudentEnroll''' and press '''Enter'''.
+| So, right-click on '''src''' folder and click '''New > Class''' and type the name of the class as''' StudentEnroll''' and press '''Enter'''.
 |-
@@ Line 77: / Line 80: @@
 |-
 |01:56
-|Now let us visualize what happens when student enrollments are done.
+|Now, let us visualize what happens when student enrollments are done.
 |-
 |02:02
-|By default '''Total Count''' is 0. The''' Name''' of the first student is '''ADIL.'''
+|By default, '''Total Count''' is 0. The''' Name''' of the first student is '''ADIL.'''
 |-
 |02:09
-|'''Id''' is''' IT101.''' '''Branch''' is''' IT.'''
+|'''Id''' is''' IT101''', '''Branch''' is''' IT.'''
 |-
@@ Line 105: / Line 108: @@
 |-
 |02:40
-|So the variable''' Total Count''' can be represented as a''' static variable'''.
+|So, the variable''' Total Count''' can be represented as a''' static variable'''.
 |-
@@ Line 117: / Line 120: @@
 |-
 |02:59
-|So these variables can be treated as''' instance variables'''
+|So, these variables can be treated as''' instance variables'''.
 |-
 | 03:04
-| Now let us look at the code representing the '''student enrollment class'''.
+| Now, let us look at the code representing the '''student enrollment class'''.
 |-
@@ Line 133: / Line 136: @@
 |-
 |03:22
-|When a '''class''' is loaded a''' static variable''' occupies a single fixed memory location.
+|When a '''class''' is loaded, a''' static variable''' occupies a single fixed memory location.
 |-
@@ Line 141: / Line 144: @@
 |-
 |03:35
-|Now click on''' Source ->''' and select''' Generate Constructor using Fields,'''
+|Now click on''' Source''' > and select''' Generate Constructor using Fields'''.
 |-
 |03:41
-|Delete the''' super keyword''' from the generated code.
+|Delete the''' super''' keyword from the generated code.
 |-
@@ Line 157: / Line 160: @@
 |-
 |03:59
-|So inside the '''constructor''' type- '''count ++ semicolon'''
+|So, inside the '''constructor''', type: '''count ++''' semicolon.
 |-
 |04:05
-|Now we will add a '''method showData'''( ) to this '''class''' to print the the values of all the variables.
+|Now we will add a method '''showData'''( ) to this '''class''', to print the values of all the variables.
 |-
 |04:13
-|So type''' public void showData( )'''  within brackets type the following code to print the values of''' id, name, branch,''' and total number of students enrolled.
+|So, type''' public void showData( )'''  within brackets type the following code to print the values of''' id, name, branch,''' and total number of students enrolled.
 |-
 |04:27
-|Now right-click on the '''default package''' and click on '''New '''-> '''Class''' and then type name as''' Demo.'''
+|Now right-click on the '''default package''' and click on '''New > Class''' and then type name as''' Demo.'''
 |-
 |04:36
-|Inside this '''class,''' we will have the '''main method'''.
+|Inside this '''class,''' we will have the '''main''' method.
 |-
 |04:39
-|So type '''main''' and then press ctrl+space to generate the''' main method.'''
+|So, type '''main''' and then press '''ctrl+space''' to generate the''' main''' method.
 |-
@@ Line 189: / Line 192: @@
 |-
 |04:57
-|So type the following code ''' StudentEnroll s1 equals new StudentEnroll'''
+|So, type the following code: ''' StudentEnroll s1 equals new StudentEnroll'''.
 |-
@@ Line 197: / Line 200: @@
 |-
 |05:08
-|Within brackets type''' IT101 '''as''' id, ADIL''' as''' name '''and''' IT''' as '''branch.'''
+|Within brackets, type''' IT101 '''as''' id, ADIL''' as''' name '''and''' IT''' as '''branch.'''
 |-
@@ Line 205: / Line 208: @@
 |-
 | 05:22
-|So type '''s1.showData( )'''. Now run the '''Demo''' program
+|So, type: '''s1.showData( )'''. Now '''run''' the '''Demo''' program.
 |-