Difference between revisions of "Java/C2/Switch-Case/English-timed"
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| − | | Welcome to the spoken tutorial on '''Switch Case | + | | Welcome to the spoken tutorial on '''Switch Case''' in Java. |
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| 00:06 | | 00:06 | ||
| − | | In this tutorial, you will learn how to use the '''switch case construct | + | | In this tutorial, you will learn how to use the '''switch case construct''' in Java. |
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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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| 00:57 | | 00:57 | ||
| − | | Inside the main method, we will create a ''' | + | | 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 | + | | 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 ''' | + | | Now, let us create a variable '''dName''' of '''type String.''' |
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| 01:18 | | 01:18 | ||
| − | | String dName | + | | String '''dName''' we can initialize 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''' stores the day number. |
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| 01:36 | | 01:36 | ||
| − | | Now, we will type the '''switch case | + | | 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. |
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| 01:52 | | 01:52 | ||
| − | | This statement defines which variable is under consideration for the cases. | + | | This statement defines which variable is under consideration for the '''cases'''. |
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| 01:59 | | 01:59 | ||
| − | | Next line | + | | Next line, type: |
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| 02:01 | | 02:01 | ||
| − | | '''case 0 | + | | '''case 0''' colon |
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| 02:04 | | 02:04 | ||
| − | |Next line '''dName | + | |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 | + | | 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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| Line 121: | Line 121: | ||
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| 02:40 | | 02:40 | ||
| − | | | + | | Similarly, let us type the remaining '''cases'''. |
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| 02:45 | | 02:45 | ||
| − | | | + | |Next line, type: '''case 1''' colon. |
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| 02:50 | | 02:50 | ||
| − | | | + | | Next line, '''dName''' equal to within double quotes '''Monday''' semicolon |
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| 02:56 | | 02:56 | ||
| − | | Next line type '''break ''' | + | | Next line, type '''break''' |
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| 02:58 | | 02:58 | ||
| − | |Then type | + | |Then type: '''case 2''' colon |
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| 03:01 | | 03:01 | ||
| − | |Next line | + | |Next line, '''dName''' equal to ''' Tuesday''' then semicolon |
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| 03:06 | | 03:06 | ||
| − | | Next line type '''break ''' | + | | Next line, type '''break''' |
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| 03:08 | | 03:08 | ||
| − | | Then next line '''case 3 | + | | Then next line, '''case 3''' colon |
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| 03:12 | | 03:12 | ||
| − | | Next line type '''dName | + | | Next line, type: '''dName''' equal to within double quotes '''Wednesday''' then semicolon |
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| 03:18 | | 03:18 | ||
| − | |Next line | + | |Next line, type '''break''' |
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| 03:20 | | 03:20 | ||
| − | | Then'''case 4 | + | | Then '''case 4''' colon |
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| 03:24 | | 03:24 | ||
| − | |Next line '''dName | + | |Next line, '''dName''' equal to within double quotes '''Thursday''' then semicolon |
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| 03:32 | | 03:32 | ||
| − | | Then'''break ''' | + | | Then '''break '''. |
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| 03:24 | | 03:24 | ||
| − | | Then next line type'''case 5 | + | | Then next line, type: '''case 5''' colon |
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| 03:37 | | 03:37 | ||
| − | | '''dName | + | | '''dName''' equal to within double quotes '''Friday''' then semicolon. |
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| 03:41 | | 03:41 | ||
| − | | Then'''break ''' | + | | Then '''break'''. |
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| 03:43 | | 03:43 | ||
| − | |Then ''' case 6 | + | |Then '''case 6''' colon |
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| 03:47 | | 03:47 | ||
| − | |Next line type | + | |Next line, type: '''dName''' equal to within double quotes '''Saturday''' then semicolon |
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| 03:55 | | 03:55 | ||
| − | |Then type | + | |Then type: '''break''' semicolon. |
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| 04:03 | | 04:03 | ||
| − | | | + | | Now Let us add a print statement and see the code in action. |
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| 04:07 | | 04:07 | ||
| − | | | + | | 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.''' |
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| 04:31 | | 04:31 | ||
| − | | Now Let us change the value of the day and see the result | + | | Now Let us change the value of the day and see the result. |
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| 04:35 | | 04:35 | ||
| − | | | + | | So change '''3''' to '''0'''. |
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| 04:46 | | 04:46 | ||
| − | | Now, what if there is no '''case''' corresponding to the value. So | + | | Now, what if there is no '''case''' corresponding to the value. So, let us see that. |
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Revision as of 20:06, 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 initialize 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 line break |
| 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 | Then case 4 colon |
| 03:24 | Next line, dName equal to within double quotes Thursday then semicolon |
| 03:32 | Then break . |
| 03:24 | Then next line, type: case 5 colon |
| 03:37 | dName equal to within double quotes Friday then semicolon. |
| 03:41 | Then break. |
| 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: Wednesday which is corresponding to the case 3. |
| 04:31 | Now Let us change the value of the day and see the result. |
| 04:35 | So change 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. |
