SELECTIONS - Introduction to Java Programming - page 108

The program generates a lottery using the random() method (line 6) and prompts the user
to enter a guess (line 11). Note that guess % 10 obtains the last digit from guess and guess
/ 10 obtains the first digit from guess , since guess is a two-digit number (lines 18-19).
The program checks the guess against the lottery number in this order:
1. First, check whether the guess matches the lottery exactly (line 24).
2. If not, check whether the reversal of the guess matches the lottery (lines 26-27).
3. If not, check whether one digit is in the lottery (lines 29-32).
4. If not, nothing matches and display "Sorry, no match" (lines 34-35).

3.14 switch Statements
A switch statement executes statements based on the value of a variable or an expression.

Key
Point

The if statement in Listing 3.6, ComputeTax.java, makes selections based on a single true
or false condition. There are four cases for computing taxes, which depend on the value of
status . To fully account for all the cases, nested if statements were used. Overuse of nested
if statements makes a program difficult to read. Java provides a switch statement to sim-
plify coding for multiple conditions. You can write the following switch statement to replace
the nested if statement in Listing 3.6:

switch (status) {
case 0 : compute tax for single filers;
break ;
case 1 : compute tax for married jointly or qualifying widow(er);
break ;
case 2 : compute tax for married filing separately;
break ;
case 3 : compute tax for head of household;
break ;
default : System.out.println( "Error: invalid status" );
System.exit( 1 );

}

The flowchart of the preceding switch statement is shown in Figure 3.6.

status is 0

Compute tax for single filers break

status is 1

Compute tax for married jointly or qualifying widow(er) break

status is 2

Compute tax for married filing separately break

status is 3

Compute tax for head of household break

default

Default actions

F IGURE 3.6 The switch statement checks all cases and executes the statements in the
matched case.