Difference between revisions of "Java/C2/Default-constructor/English-timed"
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Revision as of 14:43, 9 July 2014
| Time | Narration |
| 00:02 | Welcome to the Spoken Tutorial on default constructor in java. |
| 00:07 | In this tutorial we will learn |
| 00:10 | About the default constructor. |
| 00:12 | And to create a constructor. |
| 00:15 | Here we are using
|
| 00:26 | To follow this tutorial you must know |
| 00:29 | how to create a class and the object of the class in java using eclipse.
|
| 00:34 | If not, for relevant tutorials please visit our website which is as shown,
(http://www.spoken-tutorial.org)
|
| 00:42 | Constructor is used to initialize the instance variables.
|
| 00:46 | It is called at the creation of new object.
|
| 00:50 | Let us now see how constructor is defined in java.
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| 00:55 | So in the eclipse, I have already created a java file, Student.java |
| 01:02 | In the Student class we will declare two variables.
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| 01:07 | So type int roll_number semi-colon and String name semi-colon. |
| 01:20 | Now let us create a method. |
| 01:22 | So type void studentDetail() |
| 01:33 | Within curly brackets type System dot out dot println roll_number |
| 01:50 | Then System dot out dot println name |
| 02:03 | Now in Main method we will call this method. |
| 02:08 | So let us create an object and call the method.
|
| 02:14 | So type Student object name stu equal to new Student |
| 02:28 | Then stu dot method name i.estudentDetail |
| 02:41 | Save and Run the program. |
| 02:46 | We see the output zero and null. |
| 02:49 | So, the int variable roll_number has been initialized to its default value zero. |
| 02:56 | And the String name has been initialized to its default value null.
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| 03:02 | If we do not define a constructor then a default constructor is created.
|
| 03:08 | Default constructor has no parameters. |
| 03:11 | It initializes the instance variables to their default value.
|
| 03:16 | Now let us define a constructor. |
| 03:18 | So type Student parenthesis and curly brackets.
|
| 03:30 | Remember the Constructor has the same name as the class name to which it belongs.
|
| 03:38 | Constructors are also similar to methods but there are some important differences. |
| 03:44 | Save and Run the program. |
| 03:48 | We see the same output. |
| 03:51 | This is because the constructor, that we defined is same as having no constructor. |
| 03:58 | But here no default constructor is created because we have defined a constructor. |
| 04:06 | Now lets give values to our variables. |
| 04:11 | So inside the constructor type roll_number equal to ten semicolon. |
| 04:25 | And name equal to within double quotes Raman |
| 04:35 | Now Save and Run the program. |
| 04:43 | We see in the output that the roll_number value is ten and name is Raman. |
| 04:50 | So the constructor initializes the instance field. |
| 04:55 | Now let us see some difference between method and a constructor. |
| 05:01 | Constructor does not have a return type. |
| 05:05 | Whereas Method has a return type. |
| 05:10 | Constructor is called using the new operator. |
| 05:16 | Whereas the Method is called using the dot operator. |
| 05:21 | So this were some differences between constructor and method. |
| 05:29 | So in this tutorial, we have learnt |
| 05:32 | About the default constructor. |
| 05:34 | To define a contructor. |
| 05:36 | And Differences between method and constructor.
|
| 05:41 | For self assessment, |
| 05:42 | Create a class Employee with variables and a method to display variables. |
| 05:47 | And Create a constructor for the class Employee. |
| 05:52 | To know more about the Spoken Tutorial Project |
| 05:54 | Watch the video available at http://spoken-tutorial.org/What_is_a_Spoken_Tutorial |
| 06:00 | It summarizes the Spoken Tutorial project |
| 06:03 | If you do not have good bandwidth, you can download and watch it
|
| 06:06 | The Spoken Tutorial Project Team |
| 06:08 | Conducts workshops using spoken tutorials |
| 06:11 | Gives certificates to those who pass an online test |
| 06:14 | For more details, please write to contact@spoken-tutorial.org |
| 06:20 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
| 06:24 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
| 06:29 | More information on this Mission is available at
http://spoken-tutorial.org/NMEICT-Intro
|
| 06:38 | This brings us tothe end of the tutorial. |
| 06:40 | Thanks for joining. |
| 06:42 | This is Prathamesh Salunke signing off. Jai Hind. |
