/*
* Copyright © 2003 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*/
package java.lang;
/**
* The Float class wraps a value of primitive type <code>float</code> in
* an object. An object of type <code>Float</code> contains a single
* field whose type is <code>float</code>.
* <p>
* In addition, this class provides several methods for converting a
* <code>float</code> to a <code>String</code> and a
* <code>String</code> to a <code>float</code>, as well as other
* constants and methods useful when dealing with a
* <code>float</code>.
*
* @author Lee Boynton
* @author Arthur van Hoff
* @version 12/17/01 (CLDC 1.1)
* @since JDK1.0, CLDC 1.1
*/
public final class Float {
/**
* The positive infinity of type <code>float</code>. It is equal
* to the value returned by
* <code>Float.intBitsToFloat(0x7f800000)</code>.
*/
public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
/**
* The negative infinity of type <code>float</code>. It is equal
* to the value returned by
* <code>Float.intBitsToFloat(0xff800000)</code>.
*/
public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
/**
* The Not-a-Number (NaN) value of type <code>float</code>.
* It is equal to the value returned by
* <code>Float.intBitsToFloat(0x7fc00000)</code>.
*/
public static final float NaN = 0.0f / 0.0f;
/**
* The largest positive value of type <code>float</code>. It is
* equal to the value returned by
* <code>Float.intBitsToFloat(0x7f7fffff)</code>.
*/
public static final float MAX_VALUE = 3.40282346638528860e+38f;
/**
* The smallest positive value of type <code>float</code>. It
* is equal to the value returned by
* <code>Float.intBitsToFloat(0x1)</code>.
*/
public static final float MIN_VALUE = 1.40129846432481707e-45f;
/**
* Returns a String representation for the specified float value.
* The argument is converted to a readable string format as follows.
* All characters and characters in strings mentioned below are ASCII
* characters.
* <ul>
* <li>If the argument is NaN, the result is the string <tt>"NaN"</tt>.
* <li>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 <tt>'-'</tt>
* (<tt>'\u002d'</tt>); if the sign is positive, no sign character
* appears in the result. As for the magnitude <var>m</var>:
* <ul>
* <li>If <var>m</var> is infinity, it is represented by the characters
* <tt>"Infinity"</tt>; thus, positive infinity produces the result
* <tt>"Infinity"</tt> and negative infinity produces the result
* <tt>"-Infinity"</tt>.
* <li>If <var>m</var> is zero, it is represented by the characters
* <tt>"0.0"</tt>; thus, negative zero produces the result
* <tt>"-0.0"</tt> and positive zero produces the result
* <tt>"0.0"</tt>.
* <li> If <var>m</var> is greater than or equal to 10<sup>-3</sup> but
* less than 10<sup>7</sup>, then it is represented as the integer
* part of <var>m</var>, in decimal form with no leading zeroes,
* followed by <tt>'.'</tt> (<tt>\u002E</tt>), followed by one or
* more decimal digits representing the fractional part of
* <var>m</var>.
* <li> If <var>m</var> is less than 10<sup>-3</sup> or not less than
* 10<sup>7</sup>, then it is represented in so-called "computerized
* scientific notation." Let <var>n</var> be the unique integer
* such that 10<sup>n</sup><=<var>m</var><1; then let
* <var>a</var> be the mathematically exact quotient of <var>m</var>
* and 10<sup>n</sup> so that 1<<var>a</var><10. The magnitude
* is then represented as the integer part of <var>a</var>, as a
* single decimal digit, followed by <tt>'.'</tt> (<tt>\u002E</tt>),
* followed by decimal digits representing the fractional part of
* <var>a</var>, followed by the letter <tt>'E'</tt>
* (<tt>\u0045</tt>), followed by a representation of <var>n</var>
* as a decimal integer, as produced by the method
* <tt>{@link java.lang.Integer#toString(int)}</tt> of one argument.
* </ul>
* How many digits must be printed for the fractional part of
* <var>m</var> or <var>a</var>? 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
* <var>x</var> is the exact mathematical value represented by the
* decimal representation produced by this method for a finite nonzero
* argument <var>f</var>. Then <var>f</var> must be the float value
* nearest to <var>x</var>; or, if two float values are equally close to
* <var>x</var>then <var>f</var> must be one of them and the least
* significant bit of the significand of <var>f</var> must be <tt>0</tt>.
*
* @param f the float to be converted.
* @return a string representation of the argument.
*/
public static String toString(float f){
return new FloatingDecimal(f).toJavaFormatString();
}
/**
* Returns the floating point value represented by the specified String.
* The string <code>s</code> is interpreted as the representation of a
* floating-point value and a <code>Float</code> object representing that
* value is created and returned.
* <p>
* If <code>s</code> is <code>null</code>, then a
* <code>NullPointerException</code> is thrown.
* <p>
* Leading and trailing whitespace characters in s are ignored. The rest
* of <code>s</code> should constitute a <i>FloatValue</i> as described
* by the lexical syntax rules:
* <blockquote><pre><i>
* FloatValue:
*
* Sign<sub>opt</sub> FloatingPointLiteral
* </i></pre></blockquote>
* where <i>Sign</i>, <i>FloatingPointLiteral</i> are as defined in
* Section 3.10.2 of the
* <a href="http://java.sun.com/docs/books/jls/html/">Java Language
* Specification</a>. If it does not have the form of a <i>FloatValue</i>,
* then a <code>NumberFormatException</code> is thrown. Otherwise, it 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.
*
* @param s the string to be parsed.
* @return a newly constructed <code>Float</code> initialized to the
* value represented by the <code>String</code> argument.
* @exception NumberFormatException if the string does not contain a
* parsable number.
*/
public static Float valueOf(String s) throws NumberFormatException {
return new Float(FloatingDecimal.readJavaFormatString(s).floatValue());
}
/**
* Returns a new float initialized to the value represented by the
* specified <code>String</code>.
*
* @param s the string to be parsed.
* @return the float value represented by the string argument.
* @exception NumberFormatException if the string does not contain a
* parsable float.
* @since JDK1.2
*/
public static float parseFloat(String s) throws NumberFormatException {
return FloatingDecimal.readJavaFormatString(s).floatValue();
}
/**
* Returns true if the specified number is the special Not-a-Number (NaN)
* value.
*
* @param v the value to be tested.
* @return <code>true</code> if the argument is NaN;
* <code>false</code> otherwise.
*/
static public boolean isNaN(float v) {
return (v != v);
}
/**
* Returns true if the specified number is infinitely large in magnitude.
*
* @param v the value to be tested.
* @return <code>true</code> if the argument is positive infinity or
* negative infinity; <code>false</code> otherwise.
*/
static public boolean isInfinite(float v) {
return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
}
/**
* The value of the Float.
*/
private float value;
/**
* Constructs a newly allocated <code>Float</code> object that
* represents the primitive <code>float</code> argument.
*
* @param value the value to be represented by the <code>Float</code>.
*/
public Float(float value) {
this.value = value;
}
/**
* Constructs a newly allocated <code>Float</code>object that
* represents the argument converted to type <code>float</code>.
*
* @param value the value to be represented by the <code>Float</code>.
*/
public Float(double value) {
this.value = (float)value;
}
/**
* Constructs a newly allocated <code>Float</code> object that
* represents the floating-point value of type <code>float</code>
* represented by the string. The string is converted to a
* <code>float</code> value as if by the <code>valueOf</code> method.
*
* @param s a string to be converted to a <code>Float</code>.
* @exception NumberFormatException if the string does not contain a
* parsable number.
* @see java.lang.Float#valueOf(java.lang.String)
*/
/* REMOVED from CLDC
public Float(String s) throws NumberFormatException {
// REMIND: this is inefficient
this(valueOf(s).floatValue());
}
*/
/**
* Returns true if this <code>Float</code> value is Not-a-Number (NaN).
*
* @return <code>true</code> if the value represented by this object is
* NaN; <code>false</code> otherwise.
*/
public boolean isNaN() {
return isNaN(value);
}
/**
* Returns true if this Float value is infinitely large in magnitude.
*
* @return <code>true</code> if the value represented by this object is
* positive infinity or negative infinity;
* <code>false</code> otherwise.
*/
public boolean isInfinite() {
return isInfinite(value);
}
/**
* Returns a String representation of this Float object.
* The primitive <code>float</code> value represented by this object
* is converted to a <code>String</code> exactly as if by the method
* <code>toString</code> of one argument.
*
* @return a <code>String</code> representation of this object.
* @see java.lang.Float#toString(float)
*/
public String toString() {
return String.valueOf(value);
}
/**
* Returns the value of this Float as a byte (by casting to a byte).
*
* @since JDK1.1
*/
public byte byteValue() {
return (byte)value;
}
/**
* Returns the value of this Float as a short (by casting to a short).
*
* @since JDK1.1
*/
public short shortValue() {
return (short)value;
}
/**
* Returns the integer value of this Float (by casting to an int).
*
* @return the <code>float</code> value represented by this object
* converted to type <code>int</code> and the result of the
* conversion is returned.
*/
public int intValue() {
return (int)value;
}
/**
* Returns the long value of this Float (by casting to a long).
*
* @return the <code>float</code> value represented by this object is
* converted to type <code>long</code> and the result of the
* conversion is returned.
*/
public long longValue() {
return (long)value;
}
/**
* Returns the float value of this <tt>Float</tt> object.
*
* @return the <code>float</code> value represented by this object.
*/
public float floatValue() {
return value;
}
/**
* Returns the double value of this <tt>Float</tt> object.
*
* @return the <code>float</code> value represented by this
* object is converted to type <code>double</code> and the
* result of the conversion is returned.
*/
public double doubleValue() {
return (double)value;
}
/**
* Returns a hashcode for this <tt>Float</tt> object. The result
* is the integer bit representation, exactly as produced
* by the method {@link #floatToIntBits(float)}, of the primitive float
* value represented by this <tt>Float</tt> object.
*
* @return a hash code value for this object.
*/
public int hashCode() {
return floatToIntBits(value);
}
/**
* Compares this object against some other object.
* The result is <code>true</code> if and only if the argument is
* not <code>null</code> and is a <code>Float</code> object that
* represents a <code>float</code> that has the identical bit pattern
* to the bit pattern of the <code>float</code> represented by this
* object. For this purpose, two float values are considered to be
* the same if and only if the method {@link #floatToIntBits(float)}
* returns the same int value when applied to each.
* <p>
* Note that in most cases, for two instances of class
* <code>Float</code>, <code>f1</code> and <code>f2</code>, the value
* of <code>f1.equals(f2)</code> is <code>true</code> if and only if
* <blockquote><pre>
* f1.floatValue() == f2.floatValue()
* </pre></blockquote>
* <p>
* also has the value <code>true</code>. However, there are two exceptions:
* <ul>
* <li>If <code>f1</code> and <code>f2</code> both represent
* <code>Float.NaN</code>, then the <code>equals</code> method returns
* <code>true</code>, even though <code>Float.NaN==Float.NaN</code>
* has the value <code>false</code>.
* <li>If <code>f1</code> represents <code>+0.0f</code> while
* <code>f2</code> represents <code>-0.0f</code>, or vice versa,
* the <code>equal</code> test has the value <code>false</code>,
* even though <code>0.0f==-0.0f</code> has the value <code>true</code>.
* </ul>
* This definition allows hashtables to operate properly.
*
* @param obj the object to be compared
* @return <code>true</code> if the objects are the same;
* <code>false</code> otherwise.
* @see java.lang.Float#floatToIntBits(float)
*/
public boolean equals(Object obj) {
return (obj instanceof Float)
&& (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
}
/**
* Returns the bit representation of a single-float value.
* The result is a representation of the floating-point argument
* according to the IEEE 754 floating-point "single
* precision" bit layout.
* <ul>
* <li>Bit 31 (the bit that is selected by the mask
* <code>0x80000000</code>) represents the sign of the floating-point
* number.
* <li>Bits 30-23 (the bits that are selected by the mask
* <code>0x7f800000</code>) represent the exponent.
* <li>Bits 22-0 (the bits that are selected by the mask
* <code>0x007fffff</code>) represent the significand (sometimes called
* the mantissa) of the floating-point number.
* <li>If the argument is positive infinity, the result is
* <code>0x7f800000</code>.
* <li>If the argument is negative infinity, the result is
* <code>0xff800000</code>.
* <li>If the argument is NaN, the result is <code>0x7fc00000</code>.
* </ul>
* In all cases, the result is an integer that, when given to the
* {@link #intBitsToFloat(int)} method, will produce a floating-point
* value equal to the argument to <code>floatToIntBits</code>.
*
* @param value a floating-point number.
* @return the bits that represent the floating-point number.
*/
public static native int floatToIntBits(float value);
/**
* Returns the bit representation of a single-float value.
* The result is a representation of the floating-point argument
* according to the IEEE 754 floating-point "single
* precision" bit layout.
* <ul>
* <li>Bit 31 (the bit that is selected by the mask
* <code>0x80000000</code>) represents the sign of the floating-point
* number.
* <li>Bits 30-23 (the bits that are selected by the mask
* <code>0x7f800000</code>) represent the exponent.
* <li>Bits 22-0 (the bits that are selected by the mask
* <code>0x007fffff</code>) represent the significand (sometimes called
* the mantissa) of the floating-point number.
* <li>If the argument is positive infinity, the result is
* <code>0x7f800000</code>.
* <li>If the argument is negative infinity, the result is
* <code>0xff800000</code>.
* <p>
* If the argument is NaN, the result is the integer
* representing the actual NaN value. Unlike the <code>floatToIntBits</code>
* method, <code>intToRawIntBits</code> does not collapse NaN values.
* </ul>
* In all cases, the result is an integer that, when given to the
* {@link #intBitsToFloat(int)} method, will produce a floating-point
* value equal to the argument to <code>floatToRawIntBits</code>.
*
* @param value a floating-point number.
* @return the bits that represent the floating-point number.
*/
/* REMOVED from CLDC
public static native int floatToRawIntBits(float value);
*/
/**
* Returns the single-float corresponding to a given bit representation.
* The argument is considered to be a representation of a
* floating-point value according to the IEEE 754 floating-point
* "single precision" bit layout.
* <p>
* If the argument is <code>0x7f800000</code>, the result is positive
* infinity.
* <p>
* If the argument is <code>0xff800000</code>, the result is negative
* infinity.
* <p>
* If the argument is any value in the range <code>0x7f800001</code>
* through <code>0x7fffffff</code> or in the range
* <code>0xff800001</code> through <code>0xffffffff</code>, the result is
* NaN. All IEEE 754 NaN values of type <code>float</code> are, in effect,
* lumped together by the Java programming language into a single
* <code>float</code> value called NaN.
* <p>
* In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
* values that can be computed from the argument:
* <blockquote><pre>
* int s = ((bits >> 31) == 0) ? 1 : -1;
* int e = ((bits >> 23) & 0xff);
* int m = (e == 0) ?
* (bits & 0x7fffff) << 1 :
* (bits & 0x7fffff) | 0x800000;
* </pre></blockquote>
* Then the floating-point result equals the value of the mathematical
* expression <i>s·m·2<sup>e-150</sup></i>.
*
* @param bits an integer.
* @return the single-format floating-point value with the same bit
* pattern.
*/
public static native float intBitsToFloat(int bits);
/**
* Compares two Floats numerically. There are two ways in which
* comparisons performed by this method differ from those performed
* by the Java language numerical comparison operators (<code><, <=,
* ==, >= ></code>) when applied to primitive floats:
* <ul><li>
* <code>Float.NaN</code> is considered by this method to be
* equal to itself and greater than all other float values
* (including <code>Float.POSITIVE_INFINITY</code>).
* <li>
* <code>0.0f</code> is considered by this method to be greater
* than <code>-0.0f</code>.
* </ul>
* This ensures that Float.compareTo(Object) (which inherits its behavior
* from this method) obeys the general contract for Comparable.compareTo,
* and that the <i>natural order</i> on Floats is <i>total</i>.
*
* @param anotherFloat the <code>Float</code> to be compared.
* @return the value <code>0</code> if <code>anotherFloat</code> is
* numerically equal to this Float; a value less than
* <code>0</code> if this Float is numerically less than
* <code>anotherFloat</code>; and a value greater than
* <code>0</code> if this Float is numerically greater than
* <code>anotherFloat</code>.
*
* @since JDK1.2
* @see Comparable#compareTo(Object)
*/
/* REMOVED from CLDC
public int compareTo(Float anotherFloat) {
float thisVal = value;
float anotherVal = anotherFloat.value;
if (thisVal < anotherVal)
return -1; // Neither val is NaN, thisVal is smaller
if (thisVal > anotherVal)
return 1; // Neither val is NaN, thisVal is larger
int thisBits = Float.floatToIntBits(thisVal);
int anotherBits = Float.floatToIntBits(anotherVal);
return (thisBits == anotherBits ? 0 : // Values are equal
(thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
1)); // (0.0, -0.0) or (NaN, !NaN)
}
*/
/**
* Compares this Float to another Object. If the Object is a Float,
* this function behaves like <code>compareTo(Float)</code>. Otherwise,
* it throws a <code>ClassCastException</code> (as Floats are comparable
* only to other Floats).
*
* @param o the <code>Object</code> to be compared.
* @return the value <code>0</code> if the argument is a Float
* numerically equal to this Float; a value less than
* <code>0</code> if the argument is a Float numerically
* greater than this Float; and a value greater than
* <code>0</code> if the argument is a Float numerically
* less than this Float.
* @exception <code>ClassCastException</code> if the argument is not a
* <code>Float</code>.
* @see java.lang.Comparable
* @since 1.2
*/
/* REMOVED from CLDC
public int compareTo(Object o) {
return compareTo((Float)o);
}
*/
}
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