Difference between revisions of "Java/C2/Parameterized-constructors/English-timed"
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|| '''Narration''' | || '''Narration''' | ||
|- | |- | ||
− | | | + | | 00:02 |
| Welcome to the Spoken Tutorial on '''parameterized''' '''constructor''' in''' java'''. | | Welcome to the Spoken Tutorial on '''parameterized''' '''constructor''' in''' java'''. | ||
|- | |- | ||
− | | | + | |00:08 |
− | | | + | |In this tutorial we will learn: |
|- | |- | ||
− | | | + | |00:10 |
− | |About a ''' | + | |About a '''parameterized''' '''constructor'''. |
|- | |- | ||
− | | | + | |00:13 |
− | | And to create a '''parameterized''' '''constructor''' | + | | And to create a '''parameterized''' '''constructor'''. |
− | + | ||
− | + | ||
− | + | ||
|- | |- | ||
| 00:17 | | 00:17 | ||
− | | | + | | Here we are using: |
− | + | '''Ubuntu version 11.10 OS''' | |
− | + | '''Java Development kit 1.6''' | |
− | + | And ''' Eclipse 3.7.0''' | |
− | + | ||
− | + | ||
− | + | ||
|- | |- | ||
− | | | + | |00:29 |
− | | | + | |To follow this tutorial, you must know |
|- | |- | ||
− | | | + | |00:32 |
|how to create a default '''constructor''' in '''java''' using '''eclipse'''. | |how to create a default '''constructor''' in '''java''' using '''eclipse'''. | ||
− | |||
|- | |- | ||
− | | | + | |00:37 |
− | |If not, for relevant tutorials please visit our website which is as shown | + | |If not, for relevant tutorials, please visit our website which is as shown.http://www.spoken-tutorial.org |
− | + | ||
− | + | ||
− | + | ||
|- | |- | ||
− | | | + | |00:44 |
|What is a '''parameterized''' '''constructor'''? | |What is a '''parameterized''' '''constructor'''? | ||
+ | |||
|- | |- | ||
− | | | + | |00:48 |
− | |A '''constructor''' that | + | |A '''constructor''' that has parameters is called a '''parameterized constructor'''. |
− | + | ||
|- | |- | ||
− | | | + | |00:55 |
− | |It can have one or more than one | + | |It can have one or more than one parameters. |
|- | |- | ||
− | | 00:59 | + | |00:59 |
− | | | + | |Let us now create a '''parameterized constructor.''' |
− | + | ||
|- | |- | ||
− | | | + | |01:03 |
− | |So in the eclipse, I have ''' Student.java '''file. | + | |So in the '''eclipse''', I have ''' Student.java '''file. |
|- | |- | ||
− | | | + | |01:09 |
|We created this file in the previous tutorial. | |We created this file in the previous tutorial. | ||
|- | |- | ||
− | | | + | |01:15 |
− | | Now | + | |Now, inside the '''constructor''' we will give the variables their default value. |
− | + | ||
|- | |- | ||
− | | | + | | 01:21 |
− | |So | + | |So '''roll_number '''is equal to zero instead of ten. |
|- | |- | ||
− | | | + | | 01:27 |
− | |And | + | |And '''name''' is equal to '''null''' instead of '''Raman'''. |
|- | |- | ||
− | | | + | |01:33 |
− | | | + | |Then type '''System '''dot''' out '''dot''' println "I am a default constructor".''' |
− | + | ||
|- | |- | ||
− | | | + | |01:55 |
− | |So we have created a '''constructor''' with no parameters. | + | |So, we have created a '''constructor''' with no '''parameters'''. |
|- | |- | ||
− | | | + | |02:00 |
− | |In java, such constructor is also called a '''default | + | |In java, such constructor is also called a '''default constructor'''. |
|- | |- | ||
− | | | + | |02:07 |
− | | | + | |Now we will create another '''constructor'''. |
|- | |- | ||
− | | | + | |02:11 |
− | |So type | + | |So, type: '''Student''' parentheses. |
|- | |- | ||
− | | | + | |02:17 |
− | |Inside | + | |Inside parenthesis '''int the_roll_number '''comma''' String the_name'''. |
|- | |- | ||
− | | | + | |02:36 |
− | | | + | |So, what we have done is declared a '''constructor''' with parameters. |
|- | |- | ||
− | | | + | |02:43 |
− | |The name of the '''constructor''' '''Student''' that is the class name. | + | |The name of the '''constructor''' is '''Student''' that is the '''class''' name. |
|- | |- | ||
− | | 02:49 | + | |02:49 |
− | | | + | |Inside the parentheses, we have given two parameters to the '''constructor'''. |
|- | |- | ||
− | | | + | |02:57 |
|We can give any number of parameters to the constructor. | |We can give any number of parameters to the constructor. | ||
|- | |- | ||
− | | | + | | 03:02 |
− | | Now inside curly brackets type | + | | Now, inside curly brackets type: |
|- | |- | ||
− | | | + | |03:05 |
− | | | + | |'''System '''dot''' out '''dot''' println "I am a parameterized constructor"'''. |
|- | |- | ||
− | | | + | |03:29 |
− | | Then | + | |Then, '''roll_number''' is equal to '''the_roll_number'''. |
|- | |- | ||
− | | | + | |03:43 |
− | |And | + | |And '''name''' is equal to '''the_name'''. |
+ | |- | ||
+ | |03:53 | ||
+ | |So, we have created a '''constructor''' with '''parameters'''. | ||
− | |||
− | |||
− | |||
|- | |- | ||
| 03:58 | | 03:58 | ||
Line 152: | Line 139: | ||
|- | |- | ||
| 04:02 | | 04:02 | ||
− | | So in the main method type | + | |So, in the '''main method''' type: '''student stu2 '''equal to''' new student''' within parentheses '''11''' comma in double quotes '''Raju'''. |
+ | |||
|- | |- | ||
| 04:28 | | 04:28 | ||
− | | Let's call the '''studentDetail ''' method. | + | |Let's call the '''studentDetail ''' method. |
+ | |||
|- | |- | ||
| 04:31 | | 04:31 | ||
− | | | + | | So, type: '''stu2.studentDetail'''. |
− | |||
|- | |- | ||
− | | | + | | 04:38 |
− | | | + | | '''Save''' and '''Run''' the program. |
|- | |- | ||
− | | | + | | 04:44 |
− | | | + | | We see the '''output''' on the console. |
|- | |- | ||
− | | | + | | 04:48 |
− | | | + | | The '''default constructor''' is called first. |
|- | |- | ||
− | | | + | | 04:52 |
− | |It initializes the variables to their default | + | |It initializes the variables to their default values. |
|- | |- | ||
− | | | + | | 04:56 |
|Then the '''parameterized''' '''constructor''' is called. | |Then the '''parameterized''' '''constructor''' is called. | ||
|- | |- | ||
− | | | + | | 05:00 |
− | |It initializes the variables to the values that are passed as the | + | |It initializes the variables to the values that are passed as the arguments. |
|- | |- | ||
− | | | + | |05:05 |
|That is 11 and Raju. | |That is 11 and Raju. | ||
|- | |- | ||
− | | | + | | 05:08 |
− | | | + | | Let us see how the '''parameterized''' '''constructor''' works. |
|- | |- | ||
− | | | + | | 05:12 |
|When we call the '''parameterized''' '''constructor''', we pass two values to it. | |When we call the '''parameterized''' '''constructor''', we pass two values to it. | ||
|- | |- | ||
− | | | + | | 05:18 |
− | |These are called arguments. | + | |These are called '''arguments'''. |
|- | |- | ||
− | | | + | | 05:22 |
− | | The value | + | | The value 11 is copied to the parameter '''the_roll_number'''. |
|- | |- | ||
− | | | + | | 05:31 |
− | |And the value | + | |And the value '''Raju''' is copied to the parameter '''the_name'''. |
|- | |- | ||
− | | | + | | 05:41 |
− | | | + | | Then the value of '''the_roll_number''' is assigned to '''roll_number'''. |
|- | |- | ||
− | | | + | |05:50 |
− | |And the value of | + | |And the value of '''the_name''' is assigned to '''name'''. |
|- | |- | ||
− | | | + | | 05:55 |
− | |Hence in the | + | |Hence, in the output we see '''11 ''' and ''' Raju.''' |
|- | |- | ||
− | | | + | |06:00 |
− | | | + | | Let us see the common errors when we call a '''parameterized''' '''constructor.''' |
+ | |- | ||
+ | | 06:07 | ||
+ | |Suppose, we pass a single argument to the '''constructor'''. | ||
|- | |- | ||
− | | | + | | 06:11 |
− | | | + | | So remove '''Raju'''. |
|- | |- | ||
− | | | + | | 06:15 |
− | | | + | | We get an error. It states that '''“The constructor Student with parameter (int) is undefined.”''' |
|- | |- | ||
− | | | + | | 06:24 |
− | | | + | |So, the number of arguments must match the number of parameters. |
|- | |- | ||
− | | | + | | 06:30 |
− | | | + | |Here we can retype '''Raju''' and resolve the error. |
|- | |- | ||
− | | | + | | 06:36 |
− | + | ||
− | + | ||
− | + | ||
| Alternatively, what we can do is define another '''constructor''' with a single parameter. | | Alternatively, what we can do is define another '''constructor''' with a single parameter. | ||
|- | |- | ||
| 06:42 | | 06:42 | ||
− | | | + | | Let us do that. |
|- | |- | ||
− | | | + | |06:45 |
− | |So | + | |So,''' Student '''within parentheses''' int '''r_ number'''. |
|- | |- | ||
− | | 07:01 | + | |07:01 |
− | |Inside | + | |Inside curly brackets, type: ''' System '''dot''' out '''dot''' println''' |
|- | |- | ||
− | | | + | |07:13 |
− | | | + | |'''"I am a constructor with a single parameter"'''. |
|- | |- | ||
− | | | + | |07:29 |
− | |Then | + | |Then '''roll_number''' is equal to''' r_ number'''. |
|- | |- | ||
− | | 07:48 | + | |07:48 |
− | | | + | | '''Save''' the file. |
|- | |- | ||
− | | | + | | 07:51 |
|We see that the error is resolved when we define the '''constructor'''. | |We see that the error is resolved when we define the '''constructor'''. | ||
Line 283: | Line 271: | ||
|- | |- | ||
| 08:02 | | 08:02 | ||
− | | | + | | On the console we see that the roll number is assigned the value '''11.''' |
|- | |- | ||
− | | | + | | 08:08 |
− | |While name is | + | |While name is '''null''' since the '''constructor''' takes only one argument. |
|- | |- | ||
− | | | + | | 08:18 |
− | | | + | | Let us now call back our constructor with two parameters. |
|- | |- | ||
− | | | + | |08:23 |
− | |So type | + | |So, type''' Student stu3 '''is equal to''' new Student.''' |
|- | |- | ||
| 08:40 | | 08:40 | ||
− | | ''' 11 '''comma''' Raju. | + | | '''11 '''comma''' Raju.''' |
|- | |- | ||
− | | | + | |08:46 |
− | |Then | + | |Then '''Stu3 '''dot''' studentDetail'''. |
− | | | + | | |
− | | | + | |08:58 |
− | | | + | |Suppose here we pass '''11''' as '''String''',so add double quotes. |
|- | |- | ||
− | | | + | |09:08 |
|We get an error. | |We get an error. | ||
|- | |- | ||
− | | | + | | 09:10 |
− | |It states that '''“The constructor Student String | + | |It states that '''“The constructor Student String comma String is undefined.”''' |
|- | |- | ||
− | | | + | | 09:17 |
− | |So even the | + | |So even the data type of the argument must match with that of the parameter. |
|- | |- | ||
− | | | + | | 09:25 |
− | | So now remove the | + | | So now remove the quotes and '''Save''' the file. |
|- | |- | ||
− | | | + | |09:32 |
|Now we do not see an error. | |Now we do not see an error. | ||
|- | |- | ||
− | | | + | | 09:35 |
| So '''Run''' the program. | | So '''Run''' the program. | ||
|- | |- | ||
− | | | + | | 09:38 |
− | | | + | | In the output we see three '''constructors.''' |
|- | |- | ||
− | | | + | | 09:42 |
|The first one is the '''default''' '''constructor.''' | |The first one is the '''default''' '''constructor.''' | ||
|- | |- | ||
− | | | + | | 09:45 |
− | |The second one is the'''Constructor''' with one parameter. | + | |The second one is the '''Constructor''' with one parameter. |
|- | |- | ||
− | | | + | | 09:50 |
− | |And this third one is the'''Constructor''' with two parameters. | + | |And this third one is the '''Constructor''' with two parameters. |
|- | |- | ||
− | | | + | | 09:56 |
− | |This is how we create''' | + | |This is how we create '''parameterized constructor''' in java. |
− | + | ||
|- | |- | ||
− | | | + | | 10:05 |
| Why '''constructor'''? | | Why '''constructor'''? | ||
+ | |||
|- | |- | ||
− | | | + | | 10:07 |
− | | | + | |The variables in a class must be initialized each time an instance is created. |
− | + | ||
|- | |- | ||
− | | | + | |10:13 |
|It can be tedious to initialize all the variables. | |It can be tedious to initialize all the variables. | ||
− | |||
|- | |- | ||
− | | | + | |10:18 |
− | |So java allows objects to initialize themselves when they are created. | + | |So, java allows objects to initialize themselves when they are created. |
− | + | ||
|- | |- | ||
− | | | + | |10:25 |
|This is performed through the use of a '''constructor'''. | |This is performed through the use of a '''constructor'''. | ||
|- | |- | ||
− | | | + | |10:30 |
− | | So in this tutorial, we have learnt | + | |So in this tutorial, we have learnt: |
|- | |- | ||
− | | | + | |10:33 |
− | |To create '''parameterized''' '''constructor.''' | + | | To create '''parameterized''' '''constructor.''' |
|- | |- | ||
− | | | + | |10:36 |
|Functionality of '''parameterized''' '''constructor.''' | |Functionality of '''parameterized''' '''constructor.''' | ||
|- | |- | ||
− | | | + | |10:39 |
|And the advantage of using '''constructor.''' | |And the advantage of using '''constructor.''' | ||
|- | |- | ||
− | | 10:44 | + | |10:44 |
− | | | + | |For self assessment, create a class '''Employee'''. |
|- | |- | ||
− | | | + | |10:48 |
|Create '''constructors''' with different number of parameters. | |Create '''constructors''' with different number of parameters. | ||
|- | |- | ||
|10:53 | |10:53 | ||
− | |To know more about the Spoken Tutorial | + | |To know more about the Spoken Tutorial project, |
+ | |||
|- | |- | ||
− | | | + | |10:56 |
− | | | + | |watch the video available at [http://spoken-tutorial.org/What_is_a_Spoken_Tutorial]. |
+ | |||
|- | |- | ||
− | | | + | |11:02 |
− | | It summarizes the Spoken Tutorial project | + | | It summarizes the Spoken Tutorial project. |
|- | |- | ||
− | | | + | |11:06 |
− | |If you do not have good bandwidth, you can download and watch it | + | |If you do not have good bandwidth, you can download and watch it. |
− | + | ||
− | + | ||
|- | |- | ||
− | | | + | | 11:10 |
− | | | + | | The Spoken Tutorial project team: |
|- | |- | ||
− | | | + | | 11:12 |
− | | Conducts workshops using spoken tutorials | + | | Conducts workshops using spoken tutorials. |
|- | |- | ||
− | | | + | | 11:14 |
− | | Gives certificates | + | | Gives certificates to those who pass an online test. |
|- | |- | ||
− | | | + | | 11:18 |
|For more details, please write to contact@spoken-tutorial.org | |For more details, please write to contact@spoken-tutorial.org | ||
− | |||
− | |||
|- | |- | ||
− | | | + | | 11:24 |
− | | Spoken Tutorial Project is a part of the Talk to a Teacher project | + | | Spoken Tutorial Project is a part of the Talk to a Teacher project. |
|- | |- | ||
− | | | + | | 11:28 |
− | | It is supported by the National | + | | It is supported by the National mission on Education through ICT, MHRD, Government of India. |
|- | |- | ||
− | | | + | | 11:34 |
− | | More information on this | + | |More information on this mission is available at: [http://spoken-tutorial.org/NMEICT-Intro]. |
− | + | ||
− | + | ||
− | + | ||
− | + | ||
|- | |- | ||
− | | 11:43 | + | |11:43 |
− | | | + | |This brings us to the end of the tutorial. |
|- | |- | ||
− | | | + | |11:46 |
− | |Thanks for joining. | + | |Thanks for joining.This is Prathamesh Salunke, signing off. |
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
Jai Hind. | Jai Hind. | ||
|} | |} |
Latest revision as of 16:04, 9 March 2017
Time | Narration | |||
00:02 | Welcome to the Spoken Tutorial on parameterized constructor in java. | |||
00:08 | In this tutorial we will learn: | |||
00:10 | About a parameterized constructor. | |||
00:13 | And to create a parameterized constructor. | |||
00:17 | Here we are using:
Ubuntu version 11.10 OS Java Development kit 1.6 And Eclipse 3.7.0 | |||
00:29 | To follow this tutorial, you must know | |||
00:32 | how to create a default constructor in java using eclipse. | |||
00:37 | If not, for relevant tutorials, please visit our website which is as shown.http://www.spoken-tutorial.org | |||
00:44 | What is a parameterized constructor? | |||
00:48 | A constructor that has parameters is called a parameterized constructor. | |||
00:55 | It can have one or more than one parameters. | |||
00:59 | Let us now create a parameterized constructor. | |||
01:03 | So in the eclipse, I have Student.java file. | |||
01:09 | We created this file in the previous tutorial. | |||
01:15 | Now, inside the constructor we will give the variables their default value. | |||
01:21 | So roll_number is equal to zero instead of ten. | |||
01:27 | And name is equal to null instead of Raman. | |||
01:33 | Then type System dot out dot println "I am a default constructor". | |||
01:55 | So, we have created a constructor with no parameters. | |||
02:00 | In java, such constructor is also called a default constructor. | |||
02:07 | Now we will create another constructor. | |||
02:11 | So, type: Student parentheses. | |||
02:17 | Inside parenthesis int the_roll_number comma String the_name. | |||
02:36 | So, what we have done is declared a constructor with parameters. | |||
02:43 | The name of the constructor is Student that is the class name. | |||
02:49 | Inside the parentheses, we have given two parameters to the constructor. | |||
02:57 | We can give any number of parameters to the constructor. | |||
03:02 | Now, inside curly brackets type: | |||
03:05 | System dot out dot println "I am a parameterized constructor". | |||
03:29 | Then, roll_number is equal to the_roll_number. | |||
03:43 | And name is equal to the_name. | |||
03:53 | So, we have created a constructor with parameters. | |||
03:58 | Now let's call this constructor. | |||
04:02 | So, in the main method type: student stu2 equal to new student within parentheses 11 comma in double quotes Raju. | |||
04:28 | Let's call the studentDetail method. | |||
04:31 | So, type: stu2.studentDetail. | |||
04:38 | Save and Run the program. | |||
04:44 | We see the output on the console. | |||
04:48 | The default constructor is called first. | |||
04:52 | It initializes the variables to their default values. | |||
04:56 | Then the parameterized constructor is called. | |||
05:00 | It initializes the variables to the values that are passed as the arguments. | |||
05:05 | That is 11 and Raju. | |||
05:08 | Let us see how the parameterized constructor works. | |||
05:12 | When we call the parameterized constructor, we pass two values to it. | |||
05:18 | These are called arguments. | |||
05:22 | The value 11 is copied to the parameter the_roll_number. | |||
05:31 | And the value Raju is copied to the parameter the_name. | |||
05:41 | Then the value of the_roll_number is assigned to roll_number. | |||
05:50 | And the value of the_name is assigned to name. | |||
05:55 | Hence, in the output we see 11 and Raju. | |||
06:00 | Let us see the common errors when we call a parameterized constructor. | |||
06:07 | Suppose, we pass a single argument to the constructor. | |||
06:11 | So remove Raju. | |||
06:15 | We get an error. It states that “The constructor Student with parameter (int) is undefined.” | |||
06:24 | So, the number of arguments must match the number of parameters. | |||
06:30 | Here we can retype Raju and resolve the error. | |||
06:36 | Alternatively, what we can do is define another constructor with a single parameter. | |||
06:42 | Let us do that. | |||
06:45 | So, Student within parentheses int r_ number. | |||
07:01 | Inside curly brackets, type: System dot out dot println | |||
07:13 | "I am a constructor with a single parameter". | |||
07:29 | Then roll_number is equal to r_ number. | |||
07:48 | Save the file. | |||
07:51 | We see that the error is resolved when we define the constructor. | |||
07:58 | Let's Run the program. | |||
08:02 | On the console we see that the roll number is assigned the value 11. | |||
08:08 | While name is null since the constructor takes only one argument. | |||
08:18 | Let us now call back our constructor with two parameters. | |||
08:23 | So, type Student stu3 is equal to new Student. | |||
08:40 | 11 comma Raju. | |||
08:46 | Then Stu3 dot studentDetail. | 08:58 | Suppose here we pass 11 as String,so add double quotes. | |
09:08 | We get an error. | |||
09:10 | It states that “The constructor Student String comma String is undefined.” | |||
09:17 | So even the data type of the argument must match with that of the parameter. | |||
09:25 | So now remove the quotes and Save the file. | |||
09:32 | Now we do not see an error. | |||
09:35 | So Run the program. | |||
09:38 | In the output we see three constructors. | |||
09:42 | The first one is the default constructor. | |||
09:45 | The second one is the Constructor with one parameter. | |||
09:50 | And this third one is the Constructor with two parameters. | |||
09:56 | This is how we create parameterized constructor in java. | |||
10:05 | Why constructor? | |||
10:07 | The variables in a class must be initialized each time an instance is created. | |||
10:13 | It can be tedious to initialize all the variables. | |||
10:18 | So, java allows objects to initialize themselves when they are created. | |||
10:25 | This is performed through the use of a constructor. | |||
10:30 | So in this tutorial, we have learnt: | |||
10:33 | To create parameterized constructor. | |||
10:36 | Functionality of parameterized constructor. | |||
10:39 | And the advantage of using constructor. | |||
10:44 | For self assessment, create a class Employee. | |||
10:48 | Create constructors with different number of parameters. | |||
10:53 | To know more about the Spoken Tutorial project, | |||
10:56 | watch the video available at [1]. | |||
11:02 | It summarizes the Spoken Tutorial project. | |||
11:06 | If you do not have good bandwidth, you can download and watch it. | |||
11:10 | The Spoken Tutorial project team: | |||
11:12 | Conducts workshops using spoken tutorials. | |||
11:14 | Gives certificates to those who pass an online test. | |||
11:18 | For more details, please write to contact@spoken-tutorial.org | |||
11:24 | Spoken Tutorial Project is a part of the Talk to a Teacher project. | |||
11:28 | It is supported by the National mission on Education through ICT, MHRD, Government of India. | |||
11:34 | More information on this mission is available at: [2]. | |||
11:43 | This brings us to the end of the tutorial. | |||
11:46 | Thanks for joining.This is Prathamesh Salunke, signing off.
Jai Hind. |