20.9

java.lang.Float

THE PACKAGE JAVA.LANG

20.9.15

public double doubleValue()

The

float

 value represented by this

Float

 object is converted ( 5.1.2) to type

double

 and the result of the conversion is returned.

Overrides the

doubleValue

 method of

Number

 ( 20.6.4).

20.9.16

public static String toString(float f)

The argument is converted to a readable string format as follows. All characters

and characters in strings mentioned below are ASCII characters.

If the argument is NaN, the result is the string

"NaN"

.

Otherwise, the result is a string that represents the sign and magnitude (abso 

lute value) of the argument. If the sign is negative, the first character of the

result is

 (

 \u002d 

); if the sign is positive, no sign character appears in

the result. As for the magnitude

m

:

N

If

m

 is infinity, it is represented by the characters  

Infinity

 ; thus, positive

infinity produces the result

"Infinity"

 and negative infinity produces the

result

" Infinity"

.

N

If

m

 is zero, it is represented by the characters

"0.0"

; thus, negative zero

produces the result

" 0.0"

 and positive zero produces the result

"0.0"

.

N

If

m

 is greater than or equal to 10

3

 but less than 10

7

, then it is represented

as the integer part of

m

, in decimal form with no leading zeroes, followed by

 . 

  (

\u002E

), followed by one or more decimal digits representing the

fractional part of

m

.

N

If

m

 is less than 10

3

 or not less than 10

7

, then it is represented in so called

 computerized scientific notation.  Let

n

 be the unique integer such that

10

n

m

<

10

n

+ 1

; then let

a

 be the mathematically exact quotient of

m

 and

10

n

 so that 1

a

<

10 . The magnitude is then represented as the integer part

of

a

, as a single decimal digit, followed by

 . 

 (

\u002E

), followed by deci 

mal digits representing the fractional part of

a

, followed by the letter

 E 

(

\u0045

), followed by a representation of

n

 as a decimal integer, as pro 

duced by the method

Integer.toString

 of one argument ( 20.7.12).

How many digits must be printed for the fractional part of

m

 or

a

? There must

be at least one digit to represent the fractional part, and beyond that as many, but

only as many, more digits as are needed to uniquely distinguish the argument

value from adjacent values of type

float

. That is, suppose that

x

 is the exact

mathematical value represented by the decimal representation produced by this

506