switch provides a better alternative for a large series of if-else-if ladder. 'switch' is another 'Control Flow' statement.
| Program to demonstrate the 'switch' selection |
class SwitchDemo { public static void main(String args[]) { int a=2; switch(a) { case 0: System.out.println("The value of a is zero"); break; case 1: System.out.println("The value of a is one"); break; case 2: System.out.println("The value of a is two"); break; default: System.out.println("The value of a is "+a); } } } Output of this program: The value of a is two switch(a) i.e. switch(2) in this example : As we have mentioned switch(2), the program will directly go to case 2: and execute all the statements under case 2 i..e first it will print 'The value of a is two' and will execute the break; statement ( break; will make the program execution come out of the switch case without executing the next cases) |
| Program to demonstrate what happens when we don't write break; statement for all the cases |
class SwitchWithoutBreak { public static void main(String args[]) { int a=0; switch(a) { case 0: System.out.println("The value of a is zero"); case 1: System.out.println("The value of a is one"); case 2: System.out.println("The value of a is two"); default: System.out.println("The value of a is "+a); } } } Output of this program: The value of a is zero The value of a is one The value of a is two The value of a is 0 switch(a) i.e. switch(0) in this example: As we've mentioned switch(0), the program execution will go to case 0: and execute all the statements under case 0, i.e. it will print "The value of a is zero". Since we've not written break; statement under case 0, the program execution will go to next case i.e. case 1 and will print :The value of a is one". Since the break; statement is not written under case 1, the program execution will go to case 2 and prints "The value of a is two". Since the break; statement is not provided in the case 2, the program execution will go to case default and prints "The value of a is 0". |
| Program to demonstrate what happens when the expression provided don't match any case |
class SwitchExpressionDontMatch { public static void main(String args[]) { int a=5; switch(a) // switch(a) i.e switch(5), there is no case 5 below { case 0: System.out.println("The value of a is zero"); case 1: System.out.println("The value of a is one"); case 2: System.out.println("The value of a is two"); default: System.out.println("The value of a is "+a); } } } Output of this program: The value of a is 5 switch(a) i.e. switch(5): After executing switch(5) in this program, the program searches for case 5 for directly jumping to that case and executing the steps under case 5. But as we don't have case 5 written in this example, the program will jump to case default and execute the statements under it i.e. in this example the program prints "The value of a is 5" |
| Program to demonstrate the switch with a different expression |
class SwitchExpression { public static void main(String args[]) { int a=1,b=1; switch(a+b) //Used expression 'a+b' instead of simple variable 'a' here { case 0: System.out.println("The value of a+b is zero"); break; case 1: System.out.println("The value of a+b is one"); break; case 2: System.out.println("The value of a+b is two"); break; default: System.out.println("The value of a+b is "+(a+b)); } } }
Output of this program:
The value of a+b is two
switch(a+b) -> switch(1+1) -> switch(2): Switch(2) will jump directly to case 2 and execute the statements under case 2. Hence this program printed "The value of a+b is two" and executed break; to get out of the switch.
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