Difference between revisions of "Java/C3/Calling-methods-of-the-superclass/English-timed"
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− | | Welcome to the spoken-tutorial on '''Calling methods of the super class.''' | + | | Welcome to the '''spoken-tutorial''' on '''Calling methods of the super class.''' |
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| 00:07 | | 00:07 | ||
− | | In this tutorial we will learn | + | | In this tutorial, we will learn: when to use the '''super keyword''' |
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| 00:13 | | 00:13 | ||
− | | How to call '''methods '''of the '''super class''' | + | | How to call '''methods '''of the '''super class''' |
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| 00:17 | | 00:17 | ||
− | | How to invoke the '''constructor '''of the '''super class''' | + | | How to invoke the '''constructor '''of the '''super class'''. |
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| 00:22 | | 00:22 | ||
− | | Here we are using | + | | Here we are using: '''Ubuntu Version 12.04''' ,'''JDK 1.7''' ,'''Eclipse 4.3.1''' |
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| 00:51 | | 00:51 | ||
− | | A '''subclass '''can use a '''superclass''' '''data '''or '''method '''using the '''super | + | | A '''subclass '''can use a '''superclass''' '''data '''or '''method '''using the '''super''' keyword. |
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| 00:58 | | 00:58 | ||
− | | The '''super | + | | The '''super''' keyword : |
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− | + | refers to the '''instance variable''' of the '''parent class,''' | |
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+ | is used to invoke '''parent class constructor''', | ||
+ | |||
+ | is used to invoke '''parent class method.''' | ||
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| 01:22 | | 01:22 | ||
− | | Now, come to the '''getDetails() | + | | Now, come to the '''getDetails()''' method. |
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| 01:41 | | 01:41 | ||
− | | We already have a '''getDetails() | + | | We already have a '''getDetails()''' method here. |
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| 01:46 | | 01:46 | ||
− | | This method | + | | This method returns the '''name '''and '''email.''' |
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| 01:51 | | 01:51 | ||
− | | So, we can use this '''getDetails() | + | | So, we can use this '''getDetails()''' method in the '''Manager class.''' |
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| 01:57 | | 01:57 | ||
− | | We will call '''getDetails() | + | | We will call '''getDetails()''' method from the '''Employee class, '''inside the '''Manager class.''' |
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| 02:04 | | 02:04 | ||
− | | So, come to the '''getDetails() method ''' in the manager class. | + | | So, come to the '''getDetails() method ''' in the '''manager''' class. |
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| 02:10 | | 02:10 | ||
− | | Inside the '''return | + | | Inside the '''return''' statement, type: '''super dot getDetails()''' ''plus slash'' n '''Manager of getDepartment().''' |
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| 02:22 | | 02:22 | ||
− | | Now, let me '''run''' the | + | | Now, let me '''run''' the program. |
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| 02:25 | | 02:25 | ||
− | | We can see that we get the '''Manager | + | | We can see that we get the '''Manager''' details. Thus we can call the method of '''superclass''' inside the '''subclass'''. |
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| 02:44 | | 02:44 | ||
− | | So inside the '''Employee class, '''type '''public | + | | So, inside the '''Employee class, '''type: '''public''' space '''Employee ''' within brackets '''String name, String email_address '''. |
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| 02:59 | | 02:59 | ||
− | | Within curly brackets, type '''this dot | + | | Within curly brackets, type: '''this dot name is equal to name semicolon''' , '''this dot email_address is equal to email_address''' |
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| 03:17 | | 03:17 | ||
− | | Now let us comment the '''setter '''and '''getter | + | | Now, let us comment the '''setter '''and '''getter''' methods. |
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| 03:23 | | 03:23 | ||
− | | Inside the '''getDetails() | + | | Inside the '''getDetails()''' method- instead of '''getName''', type '''name''' , instead of '''getEmail''', type '''email_address.''' |
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| 03:37 | | 03:37 | ||
− | | A '''subclass '''inherits all of the | + | | A '''subclass '''inherits all of the methods and variables from a '''parent class'''. |
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| 03:44 | | 03:44 | ||
− | | Note that it does not ''' | + | | Note that it does not inherit '''constructors.''' |
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| 04:10 | | 04:10 | ||
− | | So, type '''public | + | | So, type: '''public''' ''space'' '''Manager''' within brackets '''String''' ''space '' '''name comma String''' space '''email underscore address comma String''' space '''dept '''. |
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| 04:30 | | 04:30 | ||
− | |Then within curly brackets, type '''super | + | |Then, within curly brackets, type: '''super '''within brackets '''name, email underscore address semicolon'''. |
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| 04:44 | | 04:44 | ||
− | |Then type | + | |Then type: '''department is equal to dept semicolon'''. |
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| 04:51 | | 04:51 | ||
− | | Here we will comment the '''setter and getter | + | | Here we will comment the '''setter''' and '''getter''' methods. |
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| 04:56 | | 04:56 | ||
− | | Then, in the '''getDetails() | + | | Then, in the '''getDetails()''' method type: '''department '''instead of '''getDepartment.''' |
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| 05:05 | | 05:05 | ||
− | | Now, come to the '''TestEmployee | + | | Now, come to the '''TestEmployee''' class. |
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| 05:15 | | 05:15 | ||
− | | Now, inside the call to the '''Manager constructor '''type | + | | Now, inside the call to the '''Manager constructor''', type: within quotes '''Nikkita Dinesh, abc@gmail.com, Accounts'''. |
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| 05:32 | | 05:32 | ||
− | | Now, | + | | Now, '''run''' the program. |
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| 05:35 | | 05:35 | ||
− | | We get the output as shown. We get the '''Manager | + | | We get the output as shown. We get the '''Manager''' details. |
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| 05:45 | | 05:45 | ||
− | | In this tutorial we have learnt: | + | | In this tutorial, we have learnt: the '''super keyword ''' ,calling the method of the '''super class '''and invoking constructor of '''super class'''. |
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| 05:56 | | 05:56 | ||
− | | As an Assignment | + | | As an Assignment-Open the previous assignment. Call the '''Vehicle class run method '''in the '''Bike class.''' |
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| 06:04 | | 06:04 | ||
− | | | + | | The output should be: '''The Vehicle is running.''' '''The Bike is running safely.''' |
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| 06:10 | | 06:10 | ||
− | | | + | | To know more about the Spoken Tutorial Project, watch the video available at the following link. |
|- | |- | ||
| 06:17 | | 06:17 | ||
− | | It summarizes the Spoken Tutorial project . If you do not have good bandwidth, you can download and watch it | + | | It summarizes the Spoken Tutorial project . If you do not have good bandwidth, you can download and watch it. |
|- | |- | ||
| 06:26 | | 06:26 | ||
− | | The Spoken Tutorial Project Team | + | |The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials |
− | + | Gives certificates for those who pass an online test. For more details, please write to '''contact at spoken hyphen tutorial dot org'''. | |
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
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| 06:42 | | 06:42 | ||
− | | Spoken Tutorial Project is a part of the Talk to a Teacher project | + | | '''Spoken Tutorial''' Project is a part of the '''Talk to a Teacher''' project. |
|- | |- | ||
| 06:46 | | 06:46 | ||
− | | It is supported by the National Mission on Education through ICT, MHRD, Government of India | + | | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
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| 06:54 | | 06:54 | ||
− | | More information on this | + | | More information on this mission is available at: '''http://spoken-tutorial.org/NMEICT- Intro''' |
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| 07:05 | | 07:05 | ||
− | |This is | + | |This is Arya Ratish from '''IIT Bombay''', signing off. Thanks for joining. |
|} | |} |
Latest revision as of 10:36, 3 May 2019
|
|
00:01 | Welcome to the spoken-tutorial on Calling methods of the super class. |
00:07 | In this tutorial, we will learn: when to use the super keyword |
00:13 | How to call methods of the super class |
00:17 | How to invoke the constructor of the super class. |
00:22 | Here we are using: Ubuntu Version 12.04 ,JDK 1.7 ,Eclipse 4.3.1 |
00:32 | To follow this tutorial, you must have basic knowledge of Java and Eclipse IDE. |
00:39 | You must also have knowledge of subclassing and method overriding in Java. |
00:45 | If not, for relevant tutorials, please visit our website. |
00:51 | A subclass can use a superclass data or method using the super keyword. |
00:58 | The super keyword :
refers to the instance variable of the parent class, is used to invoke parent class constructor, is used to invoke parent class method. |
01:13 | Now, let us go to the IDE and to the project we created earlier. |
01:19 | Let us go to the Manager class. |
01:22 | Now, come to the getDetails() method. |
01:26 | In the return statement, let us remove Name and Email. |
01:32 | Now, let us come to the Employee class. |
01:36 | This is the parent class or super class. |
01:41 | We already have a getDetails() method here. |
01:46 | This method returns the name and email. |
01:51 | So, we can use this getDetails() method in the Manager class. |
01:57 | We will call getDetails() method from the Employee class, inside the Manager class. |
02:04 | So, come to the getDetails() method in the manager class. |
02:10 | Inside the return statement, type: super dot getDetails() plus slash n Manager of getDepartment(). |
02:22 | Now, let me run the program. |
02:25 | We can see that we get the Manager details. Thus we can call the method of superclass inside the subclass. |
02:36 | Now let us come to the Employee class. |
02:41 | Let us include a constructor here. |
02:44 | So, inside the Employee class, type: public space Employee within brackets String name, String email_address . |
02:59 | Within curly brackets, type: this dot name is equal to name semicolon , this dot email_address is equal to email_address |
03:17 | Now, let us comment the setter and getter methods. |
03:23 | Inside the getDetails() method- instead of getName, type name , instead of getEmail, type email_address. |
03:37 | A subclass inherits all of the methods and variables from a parent class. |
03:44 | Note that it does not inherit constructors. |
03:49 | But, constructors can call the non-private constructors of its superclass. |
03:55 | We do this using the keyword super from the child class constructor. |
04:01 | We will see that now. |
04:04 | For that, come to the Manager class. We will include a constructor here. |
04:10 | So, type: public space Manager within brackets String space name comma String space email underscore address comma String space dept . |
04:30 | Then, within curly brackets, type: super within brackets name, email underscore address semicolon. |
04:44 | Then type: department is equal to dept semicolon. |
04:51 | Here we will comment the setter and getter methods. |
04:56 | Then, in the getDetails() method type: department instead of getDepartment. |
05:05 | Now, come to the TestEmployee class. |
05:09 | Comment the call to the setter methods. |
05:15 | Now, inside the call to the Manager constructor, type: within quotes Nikkita Dinesh, abc@gmail.com, Accounts. |
05:32 | Now, run the program. |
05:35 | We get the output as shown. We get the Manager details. |
05:40 | In this way, we can call the constructor of the super class. |
05:45 | In this tutorial, we have learnt: the super keyword ,calling the method of the super class and invoking constructor of super class. |
05:56 | As an Assignment-Open the previous assignment. Call the Vehicle class run method in the Bike class. |
06:04 | The output should be: The Vehicle is running. The Bike is running safely. |
06:10 | To know more about the Spoken Tutorial Project, watch the video available at the following link. |
06:17 | It summarizes the Spoken Tutorial project . If you do not have good bandwidth, you can download and watch it. |
06:26 | The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials
Gives certificates for those who pass an online test. For more details, please write to contact at spoken hyphen tutorial dot org. |
06:42 | Spoken Tutorial Project is a part of the Talk to a Teacher project. |
06:46 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
06:54 | More information on this mission is available at: http://spoken-tutorial.org/NMEICT- Intro |
07:05 | This is Arya Ratish from IIT Bombay, signing off. Thanks for joining. |