EXPRESSIONS

Conditional Operator

? :

15.24

Each operand of

||

 must be of type

boolean,

 or a compile time error occurs.

The type of a conditional or expression is always

boolean

.

At run time, the left hand operand expression is evaluated first; if its value is

true

, the value of the conditional or expression is

true

 and the right hand oper 

and expression is not evaluated. If the value of the left hand operand is

false

,

then the right hand expression is evaluated and its value becomes the value of the

conditional or expression. Thus,

||

 computes the same result as

|

 on

boolean

operands. It differs only in that the right hand operand expression is evaluated

conditionally rather than always.

15.24   Conditional Operator

? :

The conditional operator

? :

 uses the boolean value of one expression to decide

which of two other expressions should be evaluated.

The conditional operator is syntactically right associative (it groups right to 

left), so that

a?b:c?d:e?f:g

 means the same as

a?b:(c?d:(e?f:g))

.

ConditionalExpression:

ConditionalOrExpression

ConditionalOrExpression

 ?

Expression

 :

ConditionalExpression

The conditional operator has three operand expressions;

?

 appears between

the first and second expressions, and

:

 appears between the second and third

expressions.

The first expression must be of type

boolean

, or a compile time error occurs.

The conditional operator may be used to choose between second and third

operands of numeric type, or second and third operands of type

boolean

, or sec 

ond and third operands that are each of either reference type or the null type. All

other cases result in a compile time error.

Note that it is not permitted for either the second or the third operand expres 

sion to be an invocation of a

void

 method. In fact, it is not permitted for a condi 

tional expression to appear in any context where an invocation of a

void

 method

could appear ( 14.7).

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