CONTROL STRUCTURES I: SELECTION - Java Programming: From Problem Analysis to Program Design - page 185

Table 4-7 defines the operator || (or). From this table, it follows that Expression1 ||
Expression2 is true if and only if at least one of the expressions, Expression1 or
Expression2 ,is true ;otherwise, Expression1 || Expression2 evaluates to false .Table
4-7 is called the truth table of the operator || . Example 4-3 gives examples of the || operator.

TABLE 4-7 || (or) Operator

Expression1 Expression2 Expression1 || Expression2

4

true true true

true false true

false true true

false false false

EXAMPLE 4-3

Expression Value Explanation

true Because (14 >= 5) is true ,

('A' > 'B') is false , and
true || false is true , the
expression evaluates to true .

(14 >= 5) || ('A' > 'B')

false Because (24 >= 35) is false ,

('A' > 'B') is false ,and
false || false is false ,the
expression evaluates to false .

(24 >= 35) || ('A' > 'B')

('A' <= 'a') || (7 != 7) true

Because ('A' <= 'a') is
true , (7 != 7) is false , and
true || false is true , the
expression evaluates to true .

Order of Precedence
To work with complex logical expressions, there must be some priority scheme for
determining which operators to evaluate first. Because an expression might contain
arithmetic, relational, and logical operators, as in the expression 5 + 3 <= 9 && 2 > 3 ,
an order of precedence for the Java operators must be established. Table 4-8 shows the
order of precedence of some Java operators, including the arithmetic, relational, and
logical operators. (See Appendix B for the precedence of all Java operators.)