Difference between revisions of "Java/C2/Switch-Case/English-timed"
From Script | Spoken-Tutorial
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− | | Welcome to the spoken tutorial on '''Switch | + | | Welcome to the spoken tutorial on '''Switch Case in Java'''. |
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| 00:11 | | 00:11 | ||
− | | For this tutorial we are using | + | | For this tutorial, we are using |
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* '''Ubuntu v 11.10''' | * '''Ubuntu v 11.10''' | ||
* '''JDK 1.6''' and | * '''JDK 1.6''' and | ||
* '''Eclipse 3.7.0''' | * '''Eclipse 3.7.0''' | ||
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| 00:21 | | 00:21 | ||
| For this tutorial, you should have knowledge of if else statement in Java. | | For this tutorial, you should have knowledge of if else statement in Java. | ||
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| 00:25 | | 00:25 | ||
− | | If not, please go through the tutorials on these topics available at our website which is as shown [http://spoken-tuitorial. | + | | If not, please go through the tutorials on these topics available at our website which is as shown [http://spoken-tuitorial.org] |
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| 00:32 | | 00:32 | ||
− | | A switch case is used to perform actions based on the value of a variable. | + | | A '''switch case''' is used to perform actions based on the value of a variable. |
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| 00:39 | | 00:39 | ||
| Here is the syntax for a '''switch case statement'''. | | Here is the syntax for a '''switch case statement'''. | ||
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| 00:47 | | 00:47 | ||
| I already have '''Eclipse''' opened. | | I already have '''Eclipse''' opened. | ||
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| 00:49 | | 00:49 | ||
| I have created a '''class''' named '''SwitchCaseDemo.''' | | I have created a '''class''' named '''SwitchCaseDemo.''' | ||
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| 00:57 | | 00:57 | ||
| Inside the main method, we will create a '''variable day''' of type '''int'''. | | Inside the main method, we will create a '''variable day''' of type '''int'''. | ||
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| 01:02 | | 01:02 | ||
| So type inside the main method''' int day '''and we can give it a value '''equal to''' '''3''' semi-colon. | | So type inside the main method''' int day '''and we can give it a value '''equal to''' '''3''' semi-colon. | ||
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| 01:12 | | 01:12 | ||
| Now, let us create a '''variable dName''' of type '''String.''' | | Now, let us create a '''variable dName''' of type '''String.''' | ||
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| 01:18 | | 01:18 | ||
| String dName we can linitialize it to null. | | String dName we can linitialize it to null. | ||
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| 01:25 | | 01:25 | ||
| Here '''dName '''is a '''variable '''to hold the names of the days of a week. | | Here '''dName '''is a '''variable '''to hold the names of the days of a week. | ||
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| 01:34 | | 01:34 | ||
| '''day''' stores the '''day number'''. | | '''day''' stores the '''day number'''. | ||
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| 01:36 | | 01:36 | ||
| Now, we will type the '''switch case statement.'''So next line type | | Now, we will type the '''switch case statement.'''So next line type | ||
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| 01:43 | | 01:43 | ||
| '''switch '''within brackets''' day , '''then open curly brackets... Press enter | | '''switch '''within brackets''' day , '''then open curly brackets... Press enter | ||
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| 01:59 | | 01:59 | ||
| Next line '''type ''' | | Next line '''type ''' | ||
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| 02:01 | | 02:01 | ||
| '''case 0 '''''colon'' | | '''case 0 '''''colon'' | ||
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| 02:04 | | 02:04 | ||
|Next line '''dName '''''equal to within double quotes''''' Sunday '''''semicolon'' | |Next line '''dName '''''equal to within double quotes''''' Sunday '''''semicolon'' | ||
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| 02:14 | | 02:14 | ||
| Then type Next line'''break ''''' | | Then type Next line'''break ''''' | ||
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| 02:17 | | 02:17 | ||
| This statement says that if the day is 0, then '''dName''' must be set to '''Sunday.''' | | This statement says that if the day is 0, then '''dName''' must be set to '''Sunday.''' | ||
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| 02:26 | | 02:26 | ||
| Note that a '''break''' statement must be used at the end of each case. | | Note that a '''break''' statement must be used at the end of each case. | ||
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| 02:31 | | 02:31 | ||
| without the break statement, the switch-case functions in a complex fashion. | | without the break statement, the switch-case functions in a complex fashion. | ||
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| 02:40 | | 02:40 | ||
| Similarly, let us type the remaining cases. | | Similarly, let us type the remaining cases. | ||
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| 04:07 | | 04:07 | ||
| So next line Type '''System '''''dot '''''out '''''dot '''''println '''''within brackets '''''dName ''''' then semicolon.'' | | So next line Type '''System '''''dot '''''out '''''dot '''''println '''''within brackets '''''dName ''''' then semicolon.'' | ||
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| 04:16 | | 04:16 | ||
| Now '''Save''' and run the file. | | Now '''Save''' and run the file. | ||
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| 04:20 | | 04:20 | ||
| Now press Ctrl S and Ctrl F11 keys | | Now press Ctrl S and Ctrl F11 keys | ||
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| 04:25 | | 04:25 | ||
| we get the output as '''Wednesday'''which is corresponding to the case '''3.''' | | we get the output as '''Wednesday'''which is corresponding to the case '''3.''' | ||
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| 04:35 | | 04:35 | ||
| SoChange '''3''' to '''0''' | | SoChange '''3''' to '''0''' | ||
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| 04:38 | | 04:38 | ||
− | | | + | | Now '''Save''' and '''Run''' that file. |
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| 04:40 | | 04:40 | ||
− | | As we can see, the output is '''Sunday''' corresponding to the | + | | As we can see, the output is '''Sunday''' corresponding to the '''case 0'''. |
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| 04:46 | | 04:46 | ||
− | | Now what if there is no case corresponding to the value. So Let us see that | + | | Now, what if there is no '''case''' corresponding to the value. So Let us see that. |
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| 04 :52 | | 04 :52 | ||
− | | | + | | Change '''day''' equal to '''-1''' '''Save''' and '''run''' the file. |
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| 04:58 | | 04:58 | ||
| As we can see, there is no output. | | As we can see, there is no output. | ||
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| 05:01 | | 05:01 | ||
− | | But it would be better if we could have a case for all other values. | + | | But it would be better if we could have a '''case''' for all other values. |
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| 05:09 | | 05:09 | ||
− | |So | + | |So, after the last '''case''', type: |
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| 05:12 | | 05:12 | ||
− | | '''default | + | | '''default ''' colon |
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| 05:14 | | 05:14 | ||
− | |Next line '''dName | + | |Next line, '''dName''' equal to within double quotes '''Wrong Choice''' then semicolon |
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| 05:24 | | 05:24 | ||
− | |Next line '''break | + | |Next line, '''break ''' semicolon |
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| 05:27 | | 05:27 | ||
| We do not say '''case default'''; | | We do not say '''case default'''; | ||
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| 05:30 | | 05:30 | ||
− | | Note that we simply use the keyword '''default''' . | + | | Note that we simply use the keyword '''default'''. |
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| 05:34 | | 05:34 | ||
− | | Now let us run the code. So save and run the file | + | | Now, let us '''run''' the code. So '''save''' and '''run''' the file. |
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| 05:38 | | 05:38 | ||
− | | As we can see, the default case is executed and the required message '''Wrong choice''' is printed. | + | | As we can see, the default '''case''' is executed and the required message '''Wrong choice''' is printed. |
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| 05:48 | | 05:48 | ||
− | | Change '''-1''' to '''15''' | + | | Change '''-1''' to '''15'''. |
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| 05:51 | | 05:51 | ||
− | | As we can see, again the default case is executed. | + | | As we can see, again the default '''case''' is executed. |
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| 05:57 | | 05:57 | ||
− | | | + | | Now, let us see what happens if we remove the '''break''' statement. |
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| 06:01 | | 06:01 | ||
− | | So Let us change '''day = 15''' to '''day = 4''' | + | | So, Let us change '''day = 15''' to '''day = 4''', |
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| 06:07 | | 06:07 | ||
− | | remove the corresponding break statement for '''day =4''' | + | | remove the corresponding '''break''' statement for '''day =4'''. |
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| 06:12 | | 06:12 | ||
− | | Now Save and run | + | | Now '''Save''' and '''run'''. |
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| 06:15 | | 06:15 | ||
− | | Although the case is 4, we get the output as''' Friday''' and not '''Thursday.''' | + | | Although the '''case''' is 4, we get the output as '''Friday''' and not '''Thursday.''' |
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| 06:20 | | 06:20 | ||
− | | because of the way switch case works. | + | | because of the way '''switch case''' works. |
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| 06:24 | | 06:24 | ||
− | | First the value of day is compared with 0. | + | | First the value of '''day''' is compared with 0. |
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| 06:29 | | 06:29 | ||
− | | Then with 1 | + | | Then with 1, then with 2 and so on with all the possible '''cases'''. |
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| 06:34 | | 06:34 | ||
− | | When a match is found, it executes all the case from the match onwards. | + | | When a match is found, it executes all the '''case''' from the match onwards. |
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| 06:42 | | 06:42 | ||
− | | In our case, it executed case 5 after case 4 . | + | | In our case, it executed '''case 5''' after '''case 4'''. |
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| 06:47 | | 06:47 | ||
− | | Then it stops because of the break statement in case 5. | + | | Then it stops because of the '''break''' statement in '''case 5'''. |
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| 06:53 | | 06:53 | ||
− | |To avoid that, we need to add a '''break''' statement in each case. | + | |To avoid that, we need to add a '''break''' statement in each '''case'''. |
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| 06:57 | | 06:57 | ||
− | | | Let us now add the break statement we have removed. | + | | | Let us now add the '''break''' statement we have removed. |
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| 07:00 | | 07:00 | ||
− | | So type ''' break | + | | So, type: '''break''' semicolon. |
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| 07:05 | | 07:05 | ||
− | | Now let us run the code. | + | | Now let us '''run''' the code. |
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| 07:08 | | 07:08 | ||
| As we can see, now only '''case 4''' is executed. | | As we can see, now only '''case 4''' is executed. | ||
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| 07:13 | | 07:13 | ||
− | | As a rule, remember to use a '''break''' statement in every case to avoid errors. | + | | As a rule, remember to use a '''break''' statement in every '''case''', to avoid errors. |
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| 07:20 | | 07:20 | ||
| We have come to the end of this tutorial. | | We have come to the end of this tutorial. | ||
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| 07:22 | | 07:22 | ||
− | | In this tutorial we have learnt how to ''' | + | | In this tutorial, we have learnt how to use '''switch case construct''' and how to use '''break statement.''' |
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| 07:30 | | 07:30 | ||
− | | As an | + | | As an assignment, write a program that has a name and gender as a variable. Use a '''switch case''' statement that prints “Hello Mr....” for males and “Hello Ms...” for females. |
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| 07:44 | | 07:44 | ||
− | | To know more about the | + | | To know more about the Spoken Tutorial project, watch the video available at the following link, it summarizes the spoken-tutorial project. |
|- | |- | ||
| 07:53 | | 07:53 | ||
− | | 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. |
|- | |- | ||
| 07:58 | | 07:58 | ||
− | | The Spoken Tutorial Project Team. Conducts workshops using | + | | The Spoken Tutorial Project Team. Conducts workshops using spoken tutorials and gives certificates for those who pass an online test. |
− | + | ||
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| 08:12 | | 08:12 | ||
− | | | + | | Spoken Tutorial Project is a part of the Talk to a Teacher project and it is supported by the |
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| 08:17 | | 08:17 | ||
− | | | + | | National Mission on Education through ICT, MHRD, Government of India. |
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| 08:22 | | 08:22 | ||
− | | | + | | More information on this mission is available at '''spoken HYPHEN tutorial DOT org SLASH NMEICT HYPHEN Intro'''. |
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| 08:31 | | 08:31 | ||
| | This tutorial has been contributed by '''TalentSprint'''. Thanks for joining. | | | This tutorial has been contributed by '''TalentSprint'''. Thanks for joining. | ||
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|} | |} |
Revision as of 15:10, 25 March 2015
Time | Narration |
00:02 | Welcome to the spoken tutorial on Switch Case in Java. |
00:06 | In this tutorial, you will learn how to use the switch case construct in Java |
00:11 | For this tutorial, we are using
|
00:21 | For this tutorial, you should have knowledge of if else statement in Java. |
00:25 | If not, please go through the tutorials on these topics available at our website which is as shown [1] |
00:32 | A switch case is used to perform actions based on the value of a variable. |
00:39 | Here is the syntax for a switch case statement. |
00:44 | Let us use it now. |
00:47 | I already have Eclipse opened. |
00:49 | I have created a class named SwitchCaseDemo. |
00:53 | Now Let us add some variables. |
00:57 | Inside the main method, we will create a variable day of type int. |
01:02 | So type inside the main method int day and we can give it a value equal to 3 semi-colon. |
01:12 | Now, let us create a variable dName of type String. |
01:18 | String dName we can linitialize it to null. |
01:25 | Here dName is a variable to hold the names of the days of a week. |
01:34 | day stores the day number. |
01:36 | Now, we will type the switch case statement.So next line type |
01:43 | switch within brackets day , then open curly brackets... Press enter |
01:52 | This statement defines which variable is under consideration for the cases. |
01:59 | Next line type |
02:01 | case 0 colon |
02:04 | Next line dName equal to within double quotes Sunday semicolon |
02:14 | Then type Next linebreak |
02:17 | This statement says that if the day is 0, then dName must be set to Sunday. |
02:26 | Note that a break statement must be used at the end of each case. |
02:31 | without the break statement, the switch-case functions in a complex fashion. |
02:35 | It will be explained in subsequent part of the tutorial. |
02:40 | Similarly, let us type the remaining cases. |
02:45 | Next line type case 1 colon |
02:50 | next line dName equal to within double quotes Monday semicolon |
02:56 | Next line type break |
02:58 | Then type case 2 colon |
03:01 | Next line dName equal to Tuesday then semicolon |
03:06 | Next line type break |
03:08 | Then next line case 3 colon |
03:12 | Next line type dName equal to within double quotes Wednesday then semicolon |
03:18 | Next line type break ' |
03:20 | Thencase 4 colon |
03:24 | Next line dName equal to within double quotes Thursday then semicolon |
03:32 | Thenbreak |
03:24 | Then next line typecase 5 colon |
03:37 | dName equal to within double quotes Friday then semicolon |
03:41 | Thenbreak |
03:43 | Then case 6 colon |
03:47 | Next line type dName equal to within double quotes Saturday then semicolon |
03:55 | Then type break semicolon |
03:59 | Then close the brackets. |
04:03 | now Let us add a print statement and see the code in action. |
04:07 | So next line Type System dot out dot println within brackets dName then semicolon. |
04:16 | Now Save and run the file. |
04:20 | Now press Ctrl S and Ctrl F11 keys |
04:25 | we get the output as Wednesdaywhich is corresponding to the case 3. |
04:31 | Now Let us change the value of the day and see the result |
04:35 | SoChange 3 to 0 |
04:38 | Now Save and Run that file. |
04:40 | As we can see, the output is Sunday corresponding to the case 0. |
04:46 | Now, what if there is no case corresponding to the value. So Let us see that. |
04 :52 | Change day equal to -1 Save and run the file. |
04:58 | As we can see, there is no output. |
05:01 | But it would be better if we could have a case for all other values. |
05:06 | That is done by using the default keyword. |
05:09 | So, after the last case, type: |
05:12 | default colon |
05:14 | Next line, dName equal to within double quotes Wrong Choice then semicolon |
05:24 | Next line, break semicolon |
05:27 | We do not say case default; |
05:30 | Note that we simply use the keyword default. |
05:34 | Now, let us run the code. So save and run the file. |
05:38 | As we can see, the default case is executed and the required message Wrong choice is printed. |
05:45 | Let us try with another random value. |
05:48 | Change -1 to 15. |
05:51 | As we can see, again the default case is executed. |
05:57 | Now, let us see what happens if we remove the break statement. |
06:01 | So, Let us change day = 15 to day = 4, |
06:07 | remove the corresponding break statement for day =4. |
06:12 | Now Save and run. |
06:15 | Although the case is 4, we get the output as Friday and not Thursday. |
06:20 | because of the way switch case works. |
06:24 | First the value of day is compared with 0. |
06:29 | Then with 1, then with 2 and so on with all the possible cases. |
06:34 | When a match is found, it executes all the case from the match onwards. |
06:42 | In our case, it executed case 5 after case 4. |
06:47 | Then it stops because of the break statement in case 5. |
06:53 | To avoid that, we need to add a break statement in each case. |
06:57 | Let us now add the break statement we have removed. |
07:00 | So, type: break semicolon. |
07:05 | Now let us run the code. |
07:08 | As we can see, now only case 4 is executed. |
07:13 | As a rule, remember to use a break statement in every case, to avoid errors. |
07:20 | We have come to the end of this tutorial. |
07:22 | In this tutorial, we have learnt how to use switch case construct and how to use break statement. |
07:30 | As an assignment, write a program that has a name and gender as a variable. Use a switch case statement that prints “Hello Mr....” for males and “Hello Ms...” for females. |
07:44 | To know more about the Spoken Tutorial project, watch the video available at the following link, it summarizes the spoken-tutorial project. |
07:53 | If you do not have good bandwidth, you can download and watch it. |
07:58 | The Spoken Tutorial Project Team. Conducts workshops using spoken tutorials and gives certificates for those who pass an online test. |
08:06 | For more details, please write to contact AT spoken HYPHEN tutorial DOT org. |
08:12 | Spoken Tutorial Project is a part of the Talk to a Teacher project and it is supported by the |
08:17 | National Mission on Education through ICT, MHRD, Government of India. |
08:22 | More information on this mission is available at spoken HYPHEN tutorial DOT org SLASH NMEICT HYPHEN Intro. |
08:31 | This tutorial has been contributed by TalentSprint. Thanks for joining. |