have the same truth value.

The equality operators may be used to compare two operands of numeric

type, or two operands of type

boolean

, or two operands that are each of either ref 

erence type or the null type. All other cases result in a compile time error. The

type of an equality expression is always

boolean

.

In all cases,

a!=b

 produces the same result as

!(a==b)

. The equality opera 

tors are commutative if the operand expressions have no side effects.

15.20.1   Numerical Equality Operators

==

and

!=

If the operands of an equality operator are both of primitive numeric type, binary

numeric promotion is performed on the operands ( 5.6.2). If the promoted type of

the operands is

int

 or

long

, then an integer equality test is performed; if the pro 

moted type is

float

 or

double

, then a floating point equality test is performed.

Floating point equality testing is performed in accordance with the rules of

the IEEE 754 standard:

If either operand is NaN, then the result of

==

 is

false

 but the result of

!=

 is

true

. Indeed, the test

x!=x

 is true if and only if the value of

x

 is NaN. (The

methods

Float.isNaN

 ( 20.9.19) and

Double.isNaN

 ( 20.10.17) may also

be used to test whether a value is NaN.)

Positive zero and negative zero are considered equal. Therefore,

 0.0==0.0

 is

true

, for example.

Otherwise, two distinct floating point values are considered unequal by the

equality operators. In particular, there is one value representing positive infin 

ity and one value representing negative infinity; each compares equal only to

itself, and each compares unequal to all other values.

Subject to these considerations for floating point numbers, the following rules

then hold for integer operands or for floating point operands other than NaN:

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