Float (Java 2 Platform SE v1.4.1_"07")

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## java.lang
Class Float

    java.lang.Object
      |
      +--java.lang.Number
            |
            +--java.lang.Float

All Implemented Interfaces:
  Comparable, Serializable

public final class Float
extends Number
implements Comparable

The `Float` class wraps a value of primitive type `float` in an object. An object of type `Float` contains a single field whose type is `float`.

In addition, this class provides several methods for converting a `float` to a `String` and a `String` to a `float`, as well as other constants and methods useful when dealing with a `float`.

Since:
  JDK1.0
See Also:
  Serialized Form

Field Summary
`static float` | `MAX_VALUE` A constant holding the largest positive finite value of type `float`, (2-2-23)·2127.
`static float` | `MIN_VALUE` A constant holding the smallest positive nonzero value of type `float`, 2-149.
`static float` | `NaN` A constant holding a Not-a-Number (NaN) value of type `float`.
`static float` | `NEGATIVE_INFINITY` A constant holding the negative infinity of type `float`.
`static float` | `POSITIVE_INFINITY` A constant holding the positive infinity of type `float`.
`static Class` | `TYPE` The `Class` instance representing the primitive type `float`.

Constructor Summary
`Float(double value)` Constructs a newly allocated `Float` object that represents the argument converted to type `float`.
`Float(float value)` Constructs a newly allocated `Float` object that represents the primitive `float` argument.
`Float(String s)` Constructs a newly allocated `Float` object that represents the floating-point value of type `float` represented by the string.

Method Summary
`byte` | `byteValue()` Returns the value of this `Float` as a `byte` (by casting to a `byte`).
`static int` | `compare(float f1, float f2)` Compares the two specified `float` values.
`int` | `compareTo(Float anotherFloat)` Compares two `Float` objects numerically.
`int` | `compareTo(Object o)` Compares this `Float` object to another object.
`double` | `doubleValue()` Returns the `double` value of this `Float` object.
`boolean` | `equals(Object obj)` Compares this object against the specified object.
`static int` | `floatToIntBits(float value)` Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "single format" bit layout.
`static int` | `floatToRawIntBits(float value)` Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "single format" bit layout, preserving Not-a-Number (NaN) values.
`float` | `floatValue()` Returns the `float` value of this `Float` object.
`int` | `hashCode()` Returns a hash code for this `Float` object.
`static float` | `intBitsToFloat(int bits)` Returns the `float` value corresponding to a given bit represention.
`int` | `intValue()` Returns the value of this `Float` as an `int` (by casting to type `int`).
`boolean` | `isInfinite()` Returns `true` if this `Float` value is infinitely large in magnitude, `false` otherwise.
`static boolean` | `isInfinite(float v)` Returns `true` if the specified number is infinitely large in magnitude, `false` otherwise.
`boolean` | `isNaN()` Returns `true` if this `Float` value is a Not-a-Number (NaN), `false` otherwise.
`static boolean` | `isNaN(float v)` Returns `true` if the specified number is a Not-a-Number (NaN) value, `false` otherwise.
`long` | `longValue()` Returns value of this `Float` as a `long` (by casting to type `long`).
`static float` | `parseFloat(String s)` Returns a new `float` initialized to the value represented by the specified `String`, as performed by the `valueOf` method of class `Float`.
`short` | `shortValue()` Returns the value of this `Float` as a `short` (by casting to a `short`).
`String` | `toString()` Returns a string representation of this `Float` object.
`static String` | `toString(float f)` Returns a string representation of the `float` argument.
`static Float` | `valueOf(String s)` Returns a `Float` object holding the `float` value represented by the argument string `s`.

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

Field Detail

### POSITIVE_INFINITY

    public static final float POSITIVE_INFINITY

  A constant holding the positive infinity of type `float`. It is equal to the value returned by `Float.intBitsToFloat(0x7f800000)`.

  See Also:
    Constant Field Values

### NEGATIVE_INFINITY

    public static final float NEGATIVE_INFINITY

  A constant holding the negative infinity of type `float`. It is equal to the value returned by `Float.intBitsToFloat(0xff800000)`.

  See Also:
    Constant Field Values

### NaN

    public static final float NaN

  A constant holding a Not-a-Number (NaN) value of type `float`. It is equivalent to the value returned by `Float.intBitsToFloat(0x7fc00000)`.

  See Also:
    Constant Field Values

### MAX_VALUE

    public static final float MAX_VALUE

  A constant holding the largest positive finite value of type `float`, (2-2-23)·2127. It is equal to the value returned by `Float.intBitsToFloat(0x7f7fffff)`.

  See Also:
    Constant Field Values

### MIN_VALUE

    public static final float MIN_VALUE

  A constant holding the smallest positive nonzero value of type `float`, 2-149. It is equal to the value returned by `Float.intBitsToFloat(0x1)`.

  See Also:
    Constant Field Values

### TYPE

    public static final Class TYPE

  The `Class` instance representing the primitive type `float`.

  Since:
    JDK1.1

Constructor Detail

### Float

    public Float(float value)

  Constructs a newly allocated `Float` object that represents the primitive `float` argument.

Parameters:
  `value` - the value to be represented by the `Float`.

### Float

    public Float(double value)

  Constructs a newly allocated `Float` object that represents the argument converted to type `float`.

Parameters:
  `value` - the value to be represented by the `Float`.

### Float

    public Float(String s)
          throws NumberFormatException

  Constructs a newly allocated `Float` object that represents the floating-point value of type `float` represented by the string. The string is converted to a `float` value as if by the `valueOf` method.

Parameters:
  `s` - a string to be converted to a `Float`.
Throws:
  `NumberFormatException` - if the string does not contain a parsable number.
See Also:
  `valueOf(java.lang.String)`

Method Detail

### toString

    public static String toString(float f)

  Returns a string representation of the `float` argument. All characters 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 (absolute 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:
    - 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"`.
    - 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"`.
    - If m is greater than or equal to 10-3 but less than 107, 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.
    - If m is less than 10-3 or greater than or equal to 107, then it is represented in so-called "computerized scientific notation." Let n be the unique integer such that 10n <= m < 10n+1; then let a be the mathematically exact quotient of m and 10n 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 decimal digits representing the fractional part of a, followed by the letter '`E`' (`'\u0045'`), followed by a representation of n as a decimal integer, as produced by the method ``Integer.toString(int)``.
  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 method for a finite nonzero argument f. Then f must be the `float` value nearest to x; or, if two `float` values are equally close to x, then f must be one of them and the least significant bit of the significand of f must be `0`.

  To create localized string representations of a floating-point value, use subclasses of `NumberFormat`.

  Parameters:
    `f` - the float to be converted.
  Returns:
    a string representation of the argument.

### valueOf

    public static Float valueOf(String s)
                         throws NumberFormatException

  Returns a `Float` object holding the `float` value represented by the argument string `s`.

  If `s` is `null`, then a `NullPointerException` is thrown.

  Leading and trailing whitespace characters in `s` are ignored. The rest of `s` should constitute a FloatValue as described by the lexical syntax rules:

  > FloatValue:
  >   Signopt `NaN`
  >   Signopt `Infinity`
  >   Signopt FloatingPointLiteral

  where Sign and FloatingPointLiteral are as defined in §3.10.2 of the Java Language Specification. If `s` does not have the form of a FloatValue, then a `NumberFormatException` is thrown. Otherwise, `s` is regarded as representing an exact decimal value in the usual "computerized scientific notation"; this exact decimal value is then conceptually converted to an "infinitely precise" binary value that is then rounded to type `float` by the usual round-to-nearest rule of IEEE 754 floating-point arithmetic, which includes preserving the sign of a zero value. Finally, a `Float` object representing this `float` value is returned.

  To interpret localized string representations of a floating-point value, use subclasses of `NumberFormat`.

  Parameters:
    `s` - the string to be parsed.
  Returns:
    a `Float` object holding the value represented by the `String` argument.
  Throws:
    `NumberFormatException` - if the string does not contain a parsable number.

### parseFloat

    public static float parseFloat(String s)
                            throws NumberFormatException

  Returns a new `float` initialized to the value represented by the specified `String`, as performed by the `valueOf` method of class `Float`.

  Parameters:
    `s` - the string to be parsed.
  Returns:
    the `float` value represented by the string argument.
  Throws:
    `NumberFormatException` - if the string does not contain a parsable `float`.
  Since:
    1.2
  See Also:
    `valueOf(String)`

### isNaN

    public static boolean isNaN(float v)

  Returns `true` if the specified number is a Not-a-Number (NaN) value, `false` otherwise.

  Parameters:
    `v` - the value to be tested.
  Returns:
    `true` if the argument is NaN; `false` otherwise.

### isInfinite

    public static boolean isInfinite(float v)

  Returns `true` if the specified number is infinitely large in magnitude, `false` otherwise.

  Parameters:
    `v` - the value to be tested.
  Returns:
    `true` if the argument is positive infinity or negative infinity; `false` otherwise.

### isNaN

    public boolean isNaN()

  Returns `true` if this `Float` value is a Not-a-Number (NaN), `false` otherwise.

  Returns:
    `true` if the value represented by this object is NaN; `false` otherwise.

### isInfinite

    public boolean isInfinite()

  Returns `true` if this `Float` value is infinitely large in magnitude, `false` otherwise.

  Returns:
    `true` if the value represented by this object is positive infinity or negative infinity; `false` otherwise.

### toString

    public String toString()

  Returns a string representation of this `Float` object. The primitive `float` value represented by this object is converted to a `String` exactly as if by the method `toString` of one argument.

  Overrides:
    `toString` in class `Object`
  Returns:
    a `String` representation of this object.
  See Also:
    `toString(float)`

### byteValue

    public byte byteValue()

  Returns the value of this `Float` as a `byte` (by casting to a `byte`).

  Overrides:
    `byteValue` in class `Number`
  Returns:
    the `float` value represented by this object converted to type `byte`

### shortValue

    public short shortValue()

  Returns the value of this `Float` as a `short` (by casting to a `short`).

  Overrides:
    `shortValue` in class `Number`
  Returns:
    the `float` value represented by this object converted to type `short`
  Since:
    JDK1.1

### intValue

    public int intValue()

  Returns the value of this `Float` as an `int` (by casting to type `int`).

  Specified by:
    `intValue` in class `Number`
  Returns:
    the `float` value represented by this object converted to type `int`

### longValue

    public long longValue()

  Returns value of this `Float` as a `long` (by casting to type `long`).

  Specified by:
    `longValue` in class `Number`
  Returns:
    the `float` value represented by this object converted to type `long`

### floatValue

    public float floatValue()

  Returns the `float` value of this `Float` object.

  Specified by:
    `floatValue` in class `Number`
  Returns:
    the `float` value represented by this object

### doubleValue

    public double doubleValue()

  Returns the `double` value of this `Float` object.

  Specified by:
    `doubleValue` in class `Number`
  Returns:
    the `float` value represented by this object is converted to type `double` and the result of the conversion is returned.

### hashCode

    public int hashCode()

  Returns a hash code for this `Float` object. The result is the integer bit representation, exactly as produced by the method `floatToIntBits(float)`, of the primitive `float` value represented by this `Float` object.

  Overrides:
    `hashCode` in class `Object`
  Returns:
    a hash code value for this object.
  See Also:
    `Object.equals(java.lang.Object)`, `Hashtable`

### equals

    public boolean equals(Object obj)

  Compares this object against the specified object. The result is `true` if and only if the argument is not `null` and is a `Float` object that represents a `float` with the same value as the `float` represented by this object. For this purpose, two `float` values are considered to be the same if and only if the method `floatToIntBits(float)` returns the identical `int` value when applied to each.

  Note that in most cases, for two instances of class `Float`, `f1` and `f2`, the value of `f1.equals(f2)` is `true` if and only if

  >        f1.floatValue() == f2.floatValue()

  also has the value `true`. However, there are two exceptions:

  - If `f1` and `f2` both represent `Float.NaN`, then the `equals` method returns `true`, even though `Float.NaN==Float.NaN` has the value `false`.
  - If `f1` represents `+0.0f` while `f2` represents `-0.0f`, or vice versa, the `equal` test has the value `false`, even though `0.0f==-0.0f` has the value `true`.
  This definition allows hash tables to operate properly.

  Overrides:
    `equals` in class `Object`
  Parameters:
    `obj` - the object to be compared
  Returns:
    `true` if the objects are the same; `false` otherwise.
  See Also:
    `floatToIntBits(float)`

### floatToIntBits

    public static int floatToIntBits(float value)

  Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "single format" bit layout.

  Bit 31 (the bit that is selected by the mask `0x80000000`) represents the sign of the floating-point number. Bits 30-23 (the bits that are selected by the mask `0x7f800000`) represent the exponent. Bits 22-0 (the bits that are selected by the mask `0x007fffff`) represent the significand (sometimes called the mantissa) of the floating-point number.

  If the argument is positive infinity, the result is `0x7f800000`.

  If the argument is negative infinity, the result is `0xff800000`.

  If the argument is NaN, the result is `0x7fc00000`.

  In all cases, the result is an integer that, when given to the `intBitsToFloat(int)` method, will produce a floating-point value the same as the argument to `floatToIntBits` (except all NaN values are collapsed to a single "canonical" NaN value).

  Parameters:
    `value` - a floating-point number.
  Returns:
    the bits that represent the floating-point number.

### floatToRawIntBits

    public static int floatToRawIntBits(float value)

  Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "single format" bit layout, preserving Not-a-Number (NaN) values.

  Bit 31 (the bit that is selected by the mask `0x80000000`) represents the sign of the floating-point number. Bits 30-23 (the bits that are selected by the mask `0x7f800000`) represent the exponent. Bits 22-0 (the bits that are selected by the mask `0x007fffff`) represent the significand (sometimes called the mantissa) of the floating-point number.

  If the argument is positive infinity, the result is `0x7f800000`.

  If the argument is negative infinity, the result is `0xff800000`.

  If the argument is NaN, the result is the integer representing the actual NaN value. Unlike the `floatToIntBits` method, `intToRawIntBits` does not collapse all the bit patterns encoding a NaN to a single "canonical" NaN value.

  In all cases, the result is an integer that, when given to the `intBitsToFloat(int)` method, will produce a floating-point value the same as the argument to `floatToRawIntBits`.

  Parameters:
    `value` - a floating-point number.
  Returns:
    the bits that represent the floating-point number.

### intBitsToFloat

    public static float intBitsToFloat(int bits)

  Returns the `float` value corresponding to a given bit represention. The argument is considered to be a representation of a floating-point value according to the IEEE 754 floating-point "single format" bit layout.

  If the argument is `0x7f800000`, the result is positive infinity.

  If the argument is `0xff800000`, the result is negative infinity.

  If the argument is any value in the range `0x7f800001` through `0x7fffffff` or in the range `0xff800001` through `0xffffffff`, the result is a NaN. No IEEE 754 floating-point operation provided by Java can distinguish between two NaN values of the same type with different bit patterns. Distinct values of NaN are only distinguishable by use of the `Float.floatToRawIntBits` method.

  In all other cases, let s, e, and m be three values that can be computed from the argument:

  >      int s = ((bits >> 31) == 0) ? 1 : -1;
  >      int e = ((bits >> 23) & 0xff);
  >      int m = (e == 0) ?
  >                      (bits & 0x7fffff) << 1 :
  >                      (bits & 0x7fffff) | 0x800000;

  Then the floating-point result equals the value of the mathematical expression s·m·2e-150.

  Note that this method may not be able to return a `float` NaN with exactly same bit pattern as the `int` argument. IEEE 754 distinguishes between two kinds of NaNs, quiet NaNs and signaling NaNs. The differences between the two kinds of NaN are generally not visible in Java. Arithmetic operations on signaling NaNs turn them into quiet NaNs with a different, but often similar, bit pattern. However, on some processors merely copying a signaling NaN also performs that conversion. In particular, copying a signaling NaN to return it to the calling method may perform this conversion. So `intBitsToFloat` may not be able to return a `float` with a signaling NaN bit pattern. Consequently, for some `int` values, `floatToRawIntBits(intBitsToFloat(start))` may not equal `start`. Moreover, which particular bit patterns represent signaling NaNs is platform dependent; although all NaN bit patterns, quiet or signaling, must be in the NaN range identified above.

  Parameters:
    `bits` - an integer.
  Returns:
    the `float` floating-point value with the same bit pattern.

### compareTo

    public int compareTo(Float anotherFloat)

  Compares two `Float` objects numerically. There are two ways in which comparisons performed by this method differ from those performed by the Java language numerical comparison operators (`<, <=, ==, >= >`) when applied to primitive `float` values:
  - `Float.NaN` is considered by this method to be equal to itself and greater than all other `float` values (including `Float.POSITIVE_INFINITY`).
  - `0.0f` is considered by this method to be greater than `-0.0f`.
  This ensures that `Float.compareTo(Object)` (which forwards its behavior to this method) obeys the general contract for `Comparable.compareTo`, and that the natural order on `Float`s is consistent with equals.

  Parameters:
    `anotherFloat` - the `Float` to be compared.
  Returns:
    the value `0` if `anotherFloat` is numerically equal to this `Float`; a value less than `0` if this `Float` is numerically less than `anotherFloat`; and a value greater than `0` if this `Float` is numerically greater than `anotherFloat`.
  Since:
    1.2
  See Also:
    `Comparable.compareTo(Object)`

### compareTo

    public int compareTo(Object o)

  Compares this `Float` object to another object. If the object is a `Float`, this function behaves like `compareTo(Float)`. Otherwise, it throws a `ClassCastException` (as `Float` objects are comparable only to other `Float` objects).

  Specified by:
    `compareTo` in interface `Comparable`
  Parameters:
    `o` - the `Object` to be compared.
  Returns:
    the value `0` if the argument is a `Float` numerically equal to this `Float`; a value less than `0` if the argument is a `Float` numerically greater than this `Float`; and a value greater than `0` if the argument is a `Float` numerically less than this `Float` .
  Throws:
    ``ClassCastException`` - if the argument is not a `Float`.
  Since:
    1.2
  See Also:
    `Comparable`

### compare

    public static int compare(float f1,
                              float f2)

  Compares the two specified `float` values. The sign of the integer value returned is the same as that of the integer that would be returned by the call:

          new Float(f1).compareTo(new Float(f2))

  Parameters:
    `f1` - the first `float` to compare.
    `f2` - the second `float` to compare.
  Returns:
    the value `0` if `f1` is numerically equal to `f2`; a value less than `0` if `f1` is numerically less than `f2`; and a value greater than `0` if `f1` is numerically greater than `f2`.
  Since:
    1.4

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