Java/C2/Default-constructor/Gujarati
From Script | Spoken-Tutorial
Revision as of 10:34, 30 August 2013 by Jyotisolanki (Talk | contribs)
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
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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.
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00:34 | If not, for relevant tutorials please visit our website which is as shown,
(http://www.spoken-tutorial.org)
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00:42 | Constructor is used to initialize the instance variables.
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00:46 | It is called at the creation of new object.
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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.
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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.
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03:08 | Default constructor has no parameters. |
03:11 | It initializes the instance variables to their default value.
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03:16 | Now let us define a constructor. |
03:18 | So type Student parenthesis and curly brackets.
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03:30 | Remember the Constructor has the same name as the class name to which it belongs.
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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.
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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. |
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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. |