Conditional Structures and Loops - A Concise and Practical Introduction to Programming Algorithms in Java - page 39

2.2.5 Multiple choices: switch case

The nested if else conditional instructions presented in 2.2.3 are somehow

dicult to use in case one would like to check that a given variable is equal
to such or such a value. Indeed, nested blocks of instructions are dicult to
properly visualize on the screen. In the case of multiple choices , it is better
to use the switch case structure that branches on the appropriate set of
instructions depending on the value of a given expression. For example, consider
the code:

§

class ProgSwitch
{ public static void main( String arg [ ] ) {
System . out . print ( "Input a digit in [0..9]:" );
Scanner keyboard= new Scanner(System . in ) ;
int n=keyboard . nextInt () ;
switch (n)
case 0: System . out . println ( "zero" ); break ;
case 1: System . out . println ( "one" ); break ;
case 2: System . out . println ( "two" ); break ;
case 3: System . out . println ( "three" ); break ;
default :System.out.println( "Above three!" );
break ;
}}}

The conditional statement switch consider the elementary expression n of type
int and compare it successively with the first case: case 0 . This means that
if (n==0)Block1 else \{ ... \} . The set of instructions in a case should end
with the keyword break . Note that there is also the default case that contains
the set of instructions to execute when none of the former cases were met. The
formal syntax of the multiple choice switch case is thus:
switch (TypedExpression)
case C1 :

SetOfInstructions1 ;
break ;

case C2 :

SetOfInstructions2 ;
break ;

...
case Cn :

SetOfInstructionsn ;
break ;

default :

SetOfDefaultInstructions ;

}
}