Conditional Execution - Building Java Programs: A Back to Basics Approach - page 234

if (number > 0) {
System.out.println("Number is positive.");

}
if (number == 0) {
System.out.println("Number is zero.");

}
if (number < 0) {
System.out.println("Number is negative.");

}

No Ye s

Is test1 true?

statement1

No Ye s

Is test2 true?

statement3 statement2

Figure 4.5

Flow of nested if s ending in else

To determine how many of the println s are potentially executed, you have
to stop and think about the tests being performed. But you shouldn't have to put that
much effort into understanding this code. The code is clearer if you nest the if
statements:

if (number > 0) {
System.out.println("Number is positive.");
} else if (number == 0) {
System.out.println("Number is zero.");
} else if (number < 0) {
System.out.println("Number is negative.");

}

This solution has a problem, however. You know that you want to execute one and
only one println statement, but this nested structure does not preclude the possibil-
ity of no statement being executed (which would happen if all three tests failed).
Of course, with these particular tests that will never happen: If a number is neither
positive nor zero, it must be negative. Thus, the final test here is unnecessary and