Compound assignment operators for the boolean logical operators are defined in Table 511 The left-hand operand must be a boolean variable, and the right-hand operand must be a boolean expression An identity conversion is applied implicitly on assignment

Boolean Logical Compound Assignment Operators Expression:

Given b and a Are of Type Boolean, the Expression Is Evaluated as:

b = (b & (a)) b = (b ^ (a)) b = (b | (a))

See also the discussion on arithmetic compound assignment operators in Section 56, p 182 Here are some examples to illustrate the behavior of boolean logical compound assignment operators:

boolean b1 = false, b2 = false, b3 = false; Boolean b4 = false; b1 |= true; // true b4 ^= b1; // (1) true, unboxing in (b4 ^ b1), boxing on assignment b3 &= b1 | b2; // (2) false b3 = (b3 & (b1 | b2)) b3 = b3 & b1 | b2; // (3) true b3 = ((b3 & b1) | b2)

The assignment at (1) entails unboxing to evaluate the expression on the righthand side, followed by boxing to assign the boolean result It is also instructive to compare how the assignments at (2) and (3) above are performed, giving different results for the same value of the operands, showing how the precedence affects the evaluation

The conditional operators && and || are similar to their counterpart logical operators & and |, except that their evaluation is short-circuited Given that x and y represent values of boolean or Boolean expressions, the conditional operators are defined in Table 512 In the table, the operators are listed in decreasing precedence order

true if both operands are true; otherwise, false true if either or both operands are true; otherwise, false

Unlike their logical counterparts & and |, which can also be applied to integral operands for bitwise operations, the conditional operators && and || can only be applied to boolean operands Their evaluation results in a boolean value Truthvalues for conditional operators are shown in Table 513 Not surprisingly, they have the same truth-values as their counterpart logical operators

Note that, unlike their logical counterparts, there are no compound assignment operators for the conditional operators

In evaluation of boolean expressions involving conditional AND and OR, the lefthand operand is evaluated before the right one, and the evaluation is shortcircuited (ie, if the result of the boolean expression can be determined from the left-hand operand, the right-hand operand is not evaluated) In other words, the right-hand operand is evaluated conditionally The binary conditional operators have precedence lower than either arithmetic, relational, or logical operators, but higher than assignment operators Unboxing of the operand value takes place when necessary, before the operation is performed The following examples illustrate usage of conditional operators:

Boolean b1 = 4 == 2 && 1 < 4; boolean b2 = !b1 || 25 > 8; Boolean b3 = !(b1 && b2); boolean b4 = b1 || !b3 && b2; // // // // // // // false, short-circuit evaluated as (b1 = ((4 == 2) && (1 < 4))) true, short-circuit evaluated as (b2 = ((!b1) || (25 > 8))) true false, short-circuit evaluated as (b4 = (b1 || ((!b3) && b2)))

The order of evaluation for computing the value of boolean variable b4 proceeds as follows:

(b4 = (b1 || ((!b3) && b2))) (b4 = (false || ((!b3) && b2))) (b4 = (false || ((!true) && b2))) (b4 = (false || ((false) && b2))) (b4 = (false || false)) (b4 = false)

Note that b2 is not evaluated, short-circuiting the evaluation Example 53 illustrates the short-circuit evaluation of the initialization expressions in the declaration statements above In addition, it shows an evaluation (see the declaration of b5) involving boolean logical operators that always evaluate both operands See also Example 51 that uses a similar approach to illustrate the order of operand evaluation in arithmetic expressions