Difference between revisions of "Java/C2/Constructor-overloading/English-timed"
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− | | | + | |Within curly brackets, type '''roll_number''' is equal to '''number.''' |
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| 01:38 | | 01:38 | ||
− | | And | + | | And ''' name''' is equal to '''the_name''' |
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| 01:53 | | 01:53 | ||
− | | So in '''main method''' type | + | | So in '''main method''' type '''new Student''' parentheses semi colon |
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| 02:25 | | 02:25 | ||
− | | So within parentheses type | + | | So within parentheses type '''22''' comma in double quotes '''Ram'''. |
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| 02:36 | | 02:36 | ||
− | | | + | |Let us call the method. |
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| 02:38 | | 02:38 | ||
− | | So before '''new '''type''' Student s | + | | So before '''new ''' type '''Student s''' is equal to '''new student'''. |
+ | |||
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| 02:45 | | 02:45 | ||
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|03:03 | |03:03 | ||
− | | Now | + | | Now let us define a '''constructor''' with no parameter. |
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| 03:07 | | 03:07 | ||
− | | So type, | + | | So type, '''Student''' parentheses. |
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| 03:12 | | 03:12 | ||
− | | | + | |Within curly brackets '''roll_number''' is equal to''' 0.''' |
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| 03:21 | | 03:21 | ||
− | | And | + | | And ''' name is equal to in double quotes hyphen''' that is no name |
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| 04:35 | | 04:35 | ||
− | | So type | + | | So type '''Student s3= new Student();''' |
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| 05:52 | | 05:52 | ||
− | |Then | + | |Then Within curly bracket, '''roll_number''' is equal to '''r_no.''' |
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| 06:05 | | 06:05 | ||
− | | And | + | | And '''name''' is equal to '''the_name.''' |
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| 06:24 | | 06:24 | ||
− | | So | + | | So '''s3''' ''dot'' '''studentDetail.''' |
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| 06:35 | | 06:35 | ||
− | |So we see the output'''45''' and '''Raju''' | + | |So we see the output '''45''' and '''Raju''' |
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| 07:05 | | 07:05 | ||
− | | So type | + | | So type '''Student''' within parentheses '''int num'''. |
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| 07:16 | | 07:16 | ||
− | | | + | | within curly brackets '''roll_number '''is equalto '''num'''. |
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| 07:25 | | 07:25 | ||
− | | | + | | And '''name''' is equal to '''no''' '''name'''. |
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| 07:43 | | 07:43 | ||
− | | So type | + | | So type '''Student''' '''s4''' ''is'' ''equalto'' '''new''' '''Student''' this time we will pass an single argument. So let us pass '''61''' |
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| 08:04 | | 08:04 | ||
− | | Then | + | | Then '''s4''' dot ''' studentDetail ''' |
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Revision as of 14:30, 23 September 2014
Time | Narration |
00:03 | Welcome to the Spoken Tutorial on constructor overloading in java. |
00:08 | In this tutorial we will learn
|
00:10 | what is constructor overloading
|
00:13 | And to overload constructor
|
00:16 | Here we are using
|
00:27 | To follow this tutorial you must know
|
00:30 | how to create constructors in java using eclipse.
|
00:34 | If not, for relevant tutorials please visit our website which is as shown,
(http://www.spoken-tutorial.org) |
00:40 | What is constructor overloading? |
00:43 | Define multiple constructors for a class. |
00:46 | They must differ in number or types of parameters. |
00:50 | Let us now see how to overload constructor.
|
00:54 | In eclipse, I have a class Student with two variables and a method. |
01:03 | Let us first create a parameterized constructor.
|
01:07 | So type, Student within parentheses int number comma String the_name.
|
01:26 | Within curly brackets, type roll_number is equal to number.
|
01:38 | And name is equal to the_name
|
01:46 | So we have a constructor with two parameters. |
01:51 | let us call this constructor.
|
01:53 | So in main method type new Student parentheses semi colon |
02:03 | We see an error, it states that constructor Student is undefined.
|
02:10 | This is simply because we have defined a constructor with two parameters.
|
02:16 | And we are calling a constructor without parameters. |
02:22 | So we need to pass arguments.
|
02:25 | So within parentheses type 22 comma in double quotes Ram.
|
02:33 | We see that the error is resolved. |
02:36 | Let us call the method.
|
02:38 | So before new type Student s is equal to new student. |
02:45 | Now using the object s we will call the method studentDetail() |
02:53 | Save the program and Run. |
02:58 | We see the output 22 and Ram. |
03:03 | Now let us define a constructor with no parameter.
|
03:07 | So type, Student parentheses.
|
03:12 | Within curly brackets roll_number is equal to 0.
|
03:21 | And name is equal to in double quotes hyphen that is no name |
03:30 | So now we can call the constructor with no parameters.
|
03:35 | So type Student s1 is equal to new Student parentheses semicolon. |
03:47 | This time we see no error, since we have define a constructor without parameter |
03:55 | Then s1 dot studentDetail. |
04:01 | Save and Run the program. |
04:04 | So in the output we see zero and dash when the default constructor is called.
|
04:11 | This is constructor overloading.
|
04:13 | We have two constructor with different parameter.
|
04:17 | Both the constructor obviously have same name.
|
04:20 | So depending on the type and number of parameter, the constructor is called. |
04:26 | Let us see the advantage of constructor overloading.
|
04:30 | Suppose now call a constructor with two parameters.
|
04:35 | So type Student s3= new Student(); |
04:51 | Now within parentheses, suppose i gave the name argument first and then the roll number. |
04:58 | let see what happens. |
04:59 | So in double quotes Raju comma 45 |
05:08 | We see an error which states that the constructor student with the parameter String comma int is undefined. |
05:18 | So let us define the constructor. |
05:22 | So type Student within parentheses String the_name comma int r_no |
05:42 | So over here first parameter is string and the second parameter is int' |
05:52 | Then Within curly bracket, roll_number is equal to r_no. |
06:05 | And name is equal to the_name. |
06:15 | Save the program. |
06:18 | Now we see that the error is resolved. |
06:22 | Let us call the method. |
06:24 | So s3 dot studentDetail. |
06:29 | Save the program and Run |
06:35 | So we see the output 45 and Raju |
06:40 | So here we see that when we call the constructor. |
06:43 | We do not have to worry about the parameters that we are passing. |
06:47 | This is simply because we have define multiple constructor with different parameters. |
06:54 | So the proper constructor is overloaded. |
06:57 | We can therefore now define a constructor which takes only one parameter. |
07:02 | That is roll number. |
07:05 | So type Student within parentheses int num. |
07:16 | within curly brackets roll_number is equalto num. |
07:25 | And name is equal to no name. |
07:33 | Now let us call this constructor |
07:43 | So type Student s4 is equalto new Student this time we will pass an single argument. So let us pass 61 |
08:04 | Then s4 dot studentDetail |
08:10 | Save and Run the program |
08:14 | So in the output we see the roll number as 61 and name as no name. |
08:21 | As we can see, the proper overloaded constructor is called when new is executed. |
08:27 | Based upon the parameters specified the proper constructor is overloaded. |
08:33 | This is how constructor overloading is done. |
08:40 | So in this tutorial, we have learnt |
08:42 | About the constructor overloading. |
08:45 | to overload constructor and the use of constructor overloading |
08:50 | For self assessment, create multiple constructors for class Employeeand Overload the constructor.
|
08:58 | To know more about the Spoken Tutorial Project |
09:00 | Watch the video available at http://spoken-tutorial.org/What_is_a_Spoken_Tutorial |
09:06 | It summarizes the Spoken Tutorial project |
09:09 | If you do not have good bandwidth, you can download and watch it
|
09:12 | The Spoken Tutorial Project Team |
09:15 | Conducts workshops using spoken tutorials |
09:17 | Gives certificates to those who pass an online test |
09:20 | For more details, please write to contact@spoken-tutorial.org
|
09:26 | Spoken Tutorial Project is a part of the Talk to a Teacher project |
09:30 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
09:35 | More information on this Mission is available at |
09:43 | This brings us to the end of the tutorial |
09:46 | Thanks for joining. |
09:47 | This is Prathamesh Salunke signing off. Jai Hind. |