Difference between revisions of "Java/C3/Calling-methods-of-the-superclass/English-timed"
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| − | | The '''super''' keyword : | + | | 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''', | ||
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| + | is used to invoke '''parent class method.''' | ||
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| − | | The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials | + | |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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Latest revision as of 10:36, 3 May 2019
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| 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. |
