Java Reference
In-Depth Information
7-3. Executing Code Based on a Specified
Value
Problem
You want to execute different blocks of code based on the value of a singular expres-
sion.
Solution
Consider using a
switch
statement if your variable or expression result is one of the
allowed
switch
types and you want to test for equality against a type-compatible
constant. These examples show various ways to use the
switch
statement, including
a new feature that became available in Java 7: the ability to switch on
Strings
. First,
let's play some Rock-Paper-Scissors! The
RockPaperScissors
class shows two
different
switch
statements: one using an
int
as the
switch
expression type, and
the other using an
enum
type.
// See RockPaperScissors.java
public class RockPaperScissors {
enum Hand { ROCK, PAPER, SCISSORS, INVALID };
private static void getHand(int handVal) {
Hand hand;
try {
hand = Hand.values()[handVal - 1];
}
catch (ArrayIndexOutOfBoundsException ex) {
hand = Hand.INVALID;
}
switch (hand) {
case ROCK:
System.out.println("Rock");
break;
case PAPER:
