When Java evaluates this assignment expression, it first looks at the expression to the left of
the question mark. If denom equals zero, then the expression between the question mark and
the colon is evaluated and used as the value of the entire ? expression. If denom does not
equal zero, then the expression after the colon is evaluated and used for the value of the
entire ? expression. The result produced by the ? operator is then assigned to ratio.
Here is a program that demonstrates the ? operator. It uses it to obtain the absolute
value of a variable.
// Demonstrate ?.
class Ternary {
public static void main(String args[]) {
int i, k;
i = 10;
k = i < 0 ? -i : i; // get absolute value of i
System.out.print("Absolute value of ");
System.out.println(i + " is " + k);
i = -10;
k = i < 0 ? -i : i; // get absolute value of i
System.out.print("Absolute value of ");
System.out.println(i + " is " + k);
}
}
The output generated by the program is shown here:
Absolute value of 10 is 10
Absolute value of -10 is 10
Operator Precedence
Table 4-1 shows the order of precedence for Java operators, from highest to lowest. Notice
that the first row shows items that you may not normally think of as operators: parentheses,
square brackets, and the dot operator. Technically, these are called separators, but they act
like operators in an expression. Parentheses are used to alter the precedence of an operation.
As you know from the previous chapter, the square brackets provide array indexing. The dot
operator is used to dereference objects and will be discussed later in this topic.
Using Parentheses
Parentheses raise the precedence of the operations that are inside them. This is often necessary
to obtain the result you desire. For example, consider the following expression:
a >> b + 3
This expression first adds 3 to b and then shifts a right by that result. That is, this expression
can be rewritten using redundant parentheses like this:
a >> (b + 3)
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