More Conditionals and Loops - Java Software Solutions: Foundations of Program Design - page 270

6.1 The switch Statement

switch statement, which causes
the executing program to follow one of several paths based on a single value.
Similar logic could be constructed with multiple if statements, but in the cases
where it is warranted, a switch statement usually makes code easier to read.
The switch statement evaluates an expression to determine a value and then
matches that value with one of several possible cases. Each case has statements
associated with it. After evaluating the expression, control jumps to the state-
ment associated with the first case that matches the value. Consider the following
example:

Another conditional statement in Java is called the

switch (idChar)
{
case 'A':
aCount = aCount + 1;
break ;
case 'B':
bCount = bCount + 1;
break ;
case 'C':
cCount = cCount + 1;
break ;
default :
System.out.println ("Error in Identification Character.");
}

First, the expression is evaluated. In this example, the expression is a simple
char variable called idChar . Execution then transfers to the first statement after
the case value that matches the result of the expression. Therefore,
if idChar contains an 'A' , the variable aCount is incremented. If it
contains a 'B' , the case for 'A' is skipped and processing continues
where bCount is incremented. Likewise, if idChar contains a 'C' ,
that case is processed.
If no case value matches that of the expression, execution continues with the
optional default case, indicated by the reserved word default . If no default case
exists, no statements in the switch statement are executed and processing con-
tinues with the statement after the switch statement. It is often a good idea to
include a default case, even if you don't expect it to be executed.
When a break statement is encountered, processing jumps to the statement fol-
lowing the switch statement. A break statement is usually used to break out of
each case of a switch statement. Without a break statement, processing continues
into the next case of the switch . Therefore, if the break statement at the end of

KEY CONCEPT
A switch statement matches a
character or integer value to one of
several possible cases.