Difference between revisions of "Java/C2/Switch-Case/English-timed"
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Latest revision as of 15:07, 28 March 2017
| 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 Ubuntu v 11.10, JDK 1.6 and Eclipse 3.7.0 |
| 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 | switch case: The 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 semicolon. |
| 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 name 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 . |
| 03:34 | 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 the file. |
| 06:15 | Although the case is 4, we get the output as Friday and not Thursday. |
| 06:20 | This is 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 to 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. |
