Java/C3/Calling-methods-of-the-superclass/English-timed

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Time
Narration
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 get department.
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, String space email underscore address, 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.
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07:05 This is Arya Ratish from IIT Bombay signing off. Thanks for joining.

Contributors and Content Editors

Jyotisolanki, PoojaMoolya, Pratik kamble, Sandhya.np14