Lists, Logic, and Loops - Java 6 - page 93

else if (operation == '-')
subtract(object1, object2);
else if (operation == '*')
multiply(object1, object2);
else if (operation == '/')
divide(object1, object2);

This use of if statements is called a nested if statement because each else statement
contains another if until all possible tests have been made.

In some languages, a shorthand mechanism that you can use for nested if statements is
to group tests and actions together in a single statement. In Java, you can group actions
together with the switch statement. The following example demonstrates switch usage:

switch (grade) {
case 'A':
System.out.println(“Great job!”);
break;
case 'B':
System.out.println(“Good job!”);
break;
case 'C':
System.out.println(“You can do better!”);
break;
default:
System.out.println(“Consider cheating!”);

4

}

A switch statement is built on a test variable; in the preceding example, the variable is
the value of the grade variable, which holds a char value.

The test variable, which can be the primitive types byte , char , short , or int , is com-
pared in turn with each of the case values. If a match is found, the statement or state-
ments after the test are executed.

If no match is found, the default statement or statements are executed. Providing a
default statement is optional—if it is omitted and there is no match for any of the case
statements, the switch statement might complete without executing anything.

The Java implementation of switch is limited—tests and values can be only simple
primitive types that can be cast to an int . You cannot use larger primitive types such as
long or float , strings, or other objects within a switch , nor can you test for any rela-
tionship other than equality. These restrictions limit switch to the simplest cases. In con-
trast, nested if statements can work for any kind of test on any possible type.