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
  • Ubuntu version 11.10
  • Java Development Environment jdk 1.6 and
  • Eclipse 3.7.0


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.


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.


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.


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.

Contributors and Content Editors

Gaurav, PoojaMoolya, Sandhya.np14, Sneha