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

|  Welcome to the spoken tutorial on '''Switch case in Java'''.

|  In this tutorial, you will learn how to use the '''switch case construct in Java'''

|  For this tutorial we are using  

 

* '''Ubuntu v 11.10'''

* '''JDK 1.6''' and  

* '''Eclipse 3.7.0'''

 

 

| For this tutorial, you should have knowledge of if else statement in Java.

 

 

| If not, please go through the tutorials on these topics available at our website which is as shown [http://spoken-tuitorial.org/ http][http://spoken-tuitorial.org/ ://][http://spoken-tuitorial.org/ spoken][http://spoken-tuitorial.org/ -][http://spoken-tuitorial.org/ tutorial][http://spoken-tuitorial.org/ .][http://spoken-tuitorial.org/ org]

| A switch case is used to perform actions based on the value of a variable.

 

 

| Here is the syntax for a '''switch case statement'''.  

 

 

|   00:47

|   I already have '''Eclipse''' opened.

 

 

| Now Let us add some variables.

|  Inside the main method, we will create a '''variable day''' of type '''int'''.

 

 

| So type inside the main method''' int day '''and we can give it a value '''equal to''' '''3''' semi-colon.

 

 

| Now, let us create a '''variable dName''' of type '''String.'''

 

| String dName   we can linitialize it to null.  

 

 

 

| Here '''dName '''is a '''variable '''to hold the names of the days of a week.

 

 

| 01:34

|  '''day''' stores the '''day number'''.

 

| Now, we will type the '''switch case statement.'''So next line type

 

 

|   '''switch '''within brackets''' day , '''then open curly brackets... Press enter

 

 

 

|  This statement defines which variable is under consideration for the cases.

|  Next line '''type '''

 

 

| '''case 0 '''''colon''

 

|Next line '''dName '''''equal to within double quotes''''' Sunday '''''semicolon''

 

| Then type Next line'''break '''''

 

 

| This statement says that if the   day is 0,  then     '''dName''' must be set to '''Sunday.'''

 

 

| Note that a '''break''' statement must be used at the end of each case.

 

 

| without the break statement, the switch-case functions in a complex fashion.

 

 

|   Similarly, let us type the remaining cases.

 

| Next line type '''case 1 '''''colon''

| next line '''dName '''''equal to within double quotes''''' Monday '''''semicolon''

| Next line type '''break '''

|Then type '''case 2 '''''colon''

|Next line '''dName '''''equal to ''''' Tuesday ''''' then semicolon''

| Next line type '''break '''

| Then next line '''case 3 '''''colon''

| Next line type '''dName '''''equal to within double quotes''''' Wednesday ''''' then semicolon''

|Next line type '''break ''''

|  Then'''case 4 '''''colon''

|Next line '''dName '''''equal to within double quotes''''' Thursday ''''' then semicolon''

| Then'''break '''

| 03:24

| Then next line type'''case 5 '''''colon''

| '''dName '''''equal to within double quotes''''' Friday '''''then semicolon''

| Then'''break '''  

|Then ''' case 6 '''''colon''

|Next line type '''dName '''''equal to within double quotes''''' Saturday ''''' then semicolon''

|Then type '''break ''' semicolon

|   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.''

 

 

| Now '''Save''' and run the file.

 

| Now press Ctrl S and Ctrl F11 keys

 

 

| we get the output as '''Wednesday'''which is corresponding to the case '''3.'''

 

 

| Now Let us change the value of the  day and see the result

|  SoChange '''3''' to '''0'''

 

 

| NowSave and Run tht file  

 

 

| As we can see, the output is '''Sunday''' corresponding to the case '''0'''

 

 

| 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

| But it would be better if we could have a case for all other values.

 

 

|So After the last case, type

 

| '''default '''''colon''

|Next line '''dName '''''equal to within double quotes '''''Wrong Choice''''' then semicolon''

|Next line '''break '''''semicolon''

| Note that we simply use the keyword '''default''' .

 

| Now let us run the code. So save and run the file  

 

| As we can see, the default case is executed and the required message '''Wrong choice''' is printed.

 

 

|  Change '''-1''' to '''15'''

 

| As we can see, again the default case is executed.

|   Now let us see what happens if we remove the break statement.

|  So Let us change '''day = 15''' to '''day = 4'''

 

 

|  remove the corresponding break statement for '''day =4'''

 

 

|  Now Save and run

| Although the case is 4, we get the output as''' Friday''' and not '''Thursday.'''

|   because of the way switch case works.  

 

 

| First the value of day is compared with 0.

 

 

| Then with 1 then with 2 and so on with all the possible cases.

|  When a match is found, it executes all the case from the match onwards.

 

 

| In our case, it executed case 5 after case 4 .

 

| Then it stops because of the break statement in case 5.

|To avoid that, we need to add a '''break''' statement in each case.

|  | Let us now add the break statement we have removed.  

 

 

| So type ''' break '''''semicolon.''

 

 

| Now let us run the code.

| As a rule, remember to use a '''break''' statement in every case to avoid errors.

| In this tutorial we have learnt how to '''use switch case construct''' and '''how to use break statement.'''

|  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.

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|  | This tutorial has been contributed by '''TalentSprint'''. Thanks for joining.