Difference between revisions of "Java/C2/Switch-Case/English-timed"

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Revision as of 14:34, 9 July 2014

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 http://spoken-tutorial.org
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 NowSave and Run tht 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 assignemet 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 summarises 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.



Contributors and Content Editors

Gaurav, PoojaMoolya, Sandhya.np14, Sneha