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529 lines
17 KiB
Java
529 lines
17 KiB
Java
/* java.lang.Float
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Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.lang;
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import gnu.classpath.Configuration;
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/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
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* "The Java Language Specification", ISBN 0-201-63451-1
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* plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
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* Status: Believed complete and correct.
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*/
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/**
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* Instances of class <code>Float</code> represent primitive
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* <code>float</code> values.
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*
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* Additionally, this class provides various helper functions and variables
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* related to floats.
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*
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* @author Paul Fisher
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* @author Andrew Haley <aph@cygnus.com>
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* @since JDK 1.0
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*/
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public final class Float extends Number implements Comparable
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{
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/**
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* The maximum positive value a <code>double</code> may represent
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* is 3.4028235e+38f.
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*/
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public static final float MAX_VALUE = 3.4028235e+38f;
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/**
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* The minimum positive value a <code>float</code> may represent
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* is 1.4e-45.
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*/
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public static final float MIN_VALUE = 1.4e-45f;
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/**
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* The value of a float representation -1.0/0.0, negative infinity.
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*/
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public static final float NEGATIVE_INFINITY = -1.0f/0.0f;
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/**
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* The value of a float representation 1.0/0.0, positive infinity.
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*/
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public static final float POSITIVE_INFINITY = 1.0f/0.0f;
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/**
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* All IEEE 754 values of NaN have the same value in Java.
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*/
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public static final float NaN = 0.0f/0.0f;
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/**
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* The primitive type <code>float</code> is represented by this
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* <code>Class</code> object.
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*/
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public static final Class TYPE = VMClassLoader.getPrimitiveClass('F');
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/**
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* The immutable value of this Float.
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*/
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private final float value;
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private static final long serialVersionUID = -2671257302660747028L;
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static
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{
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if (Configuration.INIT_LOAD_LIBRARY)
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{
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System.loadLibrary ("javalang");
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}
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}
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/**
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* Create a <code>float</code> from the primitive <code>Float</code>
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* specified.
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*
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* @param value the <code>Float</code> argument
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*/
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public Float (float value)
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{
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this.value = value;
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}
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/**
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* Create a <code>Float</code> from the primitive <code>double</code>
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* specified.
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*
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* @param value the <code>double</code> argument
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*/
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public Float (double value)
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{
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this.value = (float)value;
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}
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/**
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* Create a <code>Float</code> from the specified <code>String</code>.
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*
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* This method calls <code>Float.parseFloat()</code>.
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*
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* @exception NumberFormatException when the <code>String</code> cannot
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* be parsed into a <code>Float</code>.
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* @param s the <code>String</code> to convert
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* @see #parseFloat(java.lang.String)
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*/
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public Float (String s) throws NumberFormatException
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{
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this.value = parseFloat (s);
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}
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/**
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* Parse the specified <code>String</code> as a <code>float</code>.
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*
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* The number is really read as <em>n * 10<sup>exponent</sup></em>. The
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* first number is <em>n</em>, and if there is an "<code>E</code>"
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* ("<code>e</code>" is also acceptable), then the integer after that is
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* the exponent.
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* <P>
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* Here are the possible forms the number can take:
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* <BR>
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* <TABLE BORDER=1>
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* <TR><TH>Form</TH><TH>Examples</TH></TR>
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* <TR><TD><CODE>[+-]<number>[.]</CODE></TD><TD>345., -10, 12</TD></TR>
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* <TR><TD><CODE>[+-]<number>.<number></CODE></TD><TD>40.2, 80.00, -12.30</TD></TR>
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* <TR><TD><CODE>[+-]<number>[.]E[+-]<number></CODE></TD><TD>80E12, -12e+7, 4.E-123</TD></TR>
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* <TR><TD><CODE>[+-]<number>.<number>E[+-]<number></CODE></TD><TD>6.02e-22, -40.2E+6, 12.3e9</TD></TR>
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* </TABLE>
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*
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* "<code>[+-]</code>" means either a plus or minus sign may go there, or
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* neither, in which case + is assumed.
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* <BR>
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* "<code>[.]</code>" means a dot may be placed here, but is optional.
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* <BR>
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* "<code><number></code>" means a string of digits (0-9), basically
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* an integer. "<code><number>.<number></code>" is basically
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* a real number, a floating-point value.
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* <P>
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* Remember that a <code>float</code> has a limited range. If the
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* number you specify is greater than <code>Float.MAX_VALUE</code> or less
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* than <code>-Float.MAX_VALUE</code>, it will be set at
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* <code>Float.POSITIVE_INFINITY</code> or
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* <code>Float.NEGATIVE_INFINITY</code>, respectively.
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* <P>
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*
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* Note also that <code>float</code> does not have perfect precision. Many
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* numbers cannot be precisely represented. The number you specify
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* will be rounded to the nearest representable value.
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* <code>Float.MIN_VALUE</code> is the margin of error for <code>float</code>
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* values.
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* <P>
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* If an unexpected character is found in the <code>String</code>, a
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* <code>NumberFormatException</code> will be thrown. Spaces are not
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* allowed and will cause this exception to be thrown.
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*
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* @XXX specify where/how we are not in accord with the spec.
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*
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* @param str the <code>String</code> to convert
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* @return the value of the <code>String</code> as a <code>float</code>.
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* @exception NumberFormatException when the string cannot be parsed to a
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* <code>float</code>.
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* @since JDK 1.2
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* @see #MIN_VALUE
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* @see #MAX_VALUE
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* @see #POSITIVE_INFINITY
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* @see #NEGATIVE_INFINITY
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*/
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public static float parseFloat (String s) throws NumberFormatException
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{
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// The spec says that parseFloat() should work like
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// Double.valueOf(). This is equivalent, in our implementation,
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// but more efficient.
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return (float) Double.parseDouble (s);
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}
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/**
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* Convert the <code>float</code> value of this <code>Float</code>
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* to a <code>String</code>. This method calls
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* <code>Float.toString(float)</code> to do its dirty work.
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*
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* @return the <code>String</code> representation of this <code>Float</code>.
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* @see #toString(float)
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*/
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public String toString ()
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{
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return toString (value);
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}
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/**
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* If the <code>Object</code> is not <code>null</code>, is an
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* <code>instanceof</code> <code>Float</code>, and represents
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* the same primitive <code>float</code> value return
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* <code>true</code>. Otherwise <code>false</code> is returned.
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* <p>
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* Note that there are two differences between <code>==</code> and
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* <code>equals()</code>. <code>0.0f == -0.0f</code> returns <code>true</code>
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* but <code>new Float(0.0f).equals(new Float(-0.0f))</code> returns
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* <code>false</code>. And <code>Float.NaN == Float.NaN</code> returns
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* <code>false</code>, but
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* <code>new Float(Float.NaN).equals(new Float(Float.NaN))</code> returns
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* <code>true</code>.
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*
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* @param obj the object to compare to
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* @return whether the objects are semantically equal.
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*/
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public boolean equals (Object obj)
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{
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if (!(obj instanceof Float))
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return false;
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float f = ((Float) obj).value;
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// GCJ LOCAL: this implementation is probably faster than
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// Classpath's, especially once we inline floatToIntBits.
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return floatToIntBits (value) == floatToIntBits (f);
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// END GCJ LOCAL
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}
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/**
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* Return a hashcode representing this Object.
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* <code>Float</code>'s hash code is calculated by calling the
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* <code>floatToIntBits()</code> function.
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* @return this Object's hash code.
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* @see java.lang.Float.floatToIntBits(float)
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*/
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public int hashCode ()
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{
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return floatToIntBits (value);
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}
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/**
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* Return the value of this <code>Double</code> when cast to an
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* <code>int</code>.
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*/
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public int intValue ()
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{
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return (int) value;
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}
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/**
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* Return the value of this <code>Double</code> when cast to a
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* <code>long</code>.
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*/
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public long longValue ()
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{
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return (long) value;
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}
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/**
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* Return the value of this <code>Double</code> when cast to a
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* <code>float</code>.
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*/
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public float floatValue ()
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{
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return (float) value;
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}
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/**
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* Return the primitive <code>double</code> value represented by this
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* <code>Double</code>.
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*/
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public double doubleValue ()
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{
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return (double) value;
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}
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/**
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* Convert the <code>float</code> to a <code>String</code>.
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* <P>
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*
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* Floating-point string representation is fairly complex: here is a
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* rundown of the possible values. "<CODE>[-]</CODE>" indicates that a
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* negative sign will be printed if the value (or exponent) is negative.
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* "<CODE><number></CODE>" means a string of digits (0-9).
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* "<CODE><digit></CODE>" means a single digit (0-9).
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* <P>
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*
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* <TABLE BORDER=1>
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* <TR><TH>Value of Float</TH><TH>String Representation</TH></TR>
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* <TR>
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* <TD>[+-] 0</TD>
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* <TD>[<CODE>-</CODE>]<CODE>0.0</CODE></TD>
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* </TR>
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* <TR>
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* <TD>Between [+-] 10<SUP>-3</SUP> and 10<SUP>7</SUP></TD>
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* <TD><CODE>[-]number.number</CODE></TD>
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* </TR>
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* <TR>
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* <TD>Other numeric value</TD>
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* <TD><CODE>[-]<digit>.<number>E[-]<number></CODE></TD>
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* </TR>
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* <TR>
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* <TD>[+-] infinity</TD>
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* <TD><CODE>[-]Infinity</CODE></TD>
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* </TR>
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* <TR>
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* <TD>NaN</TD>
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* <TD><CODE>NaN</CODE></TD>
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* </TR>
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* </TABLE>
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*
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* Yes, negative zero <EM>is</EM> a possible value. Note that there is
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* <EM>always</EM> a <CODE>.</CODE> and at least one digit printed after
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* it: even if the number is 3, it will be printed as <CODE>3.0</CODE>.
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* After the ".", all digits will be printed except trailing zeros. No
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* truncation or rounding is done by this function.
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*
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* @XXX specify where we are not in accord with the spec.
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*
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* @param f the <code>float</code> to convert
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* @return the <code>String</code> representing the <code>float</code>.
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*/
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public static String toString (float f)
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{
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return Double.toString ((double) f, true);
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}
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/**
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* Return the result of calling <code>new Float(java.lang.String)</code>.
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*
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* @param s the <code>String</code> to convert to a <code>Float</code>.
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* @return a new <code>Float</code> representing the <code>String</code>'s
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* numeric value.
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*
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* @exception NumberFormatException thrown if <code>String</code> cannot
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* be parsed as a <code>double</code>.
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* @see #Float(java.lang.String)
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* @see #parseFloat(java.lang.String)
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*/
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public static Float valueOf (String s) throws NumberFormatException
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{
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return new Float (s);
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}
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/**
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* Return <code>true</code> if the value of this <code>Float</code>
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* is the same as <code>NaN</code>, otherwise return <code>false</code>.
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* @return whether this <code>Float</code> is <code>NaN</code>.
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*/
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public boolean isNaN ()
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{
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return isNaN (value);
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}
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/**
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* Return <code>true</code> if the <code>float</code> has the same
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* value as <code>NaN</code>, otherwise return <code>false</code>.
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*
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* @param v the <code>float</code> to compare
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* @return whether the argument is <code>NaN</code>.
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*/
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public static boolean isNaN (float v)
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{
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// This works since NaN != NaN is the only reflexive inequality
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// comparison which returns true.
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return v != v;
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}
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/**
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* Return <code>true</code> if the value of this <code>Float</code>
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* is the same as <code>NEGATIVE_INFINITY</code> or
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* <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>.
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*
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* @return whether this <code>Float</code> is (-/+) infinity.
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*/
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public boolean isInfinite ()
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{
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return isInfinite (value);
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}
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/**
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* Return <code>true</code> if the <code>float</code> has a value
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* equal to either <code>NEGATIVE_INFINITY</code> or
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* <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>.
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*
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* @param v the <code>float</code> to compare
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* @return whether the argument is (-/+) infinity.
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*/
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public static boolean isInfinite (float v)
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{
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return (v == POSITIVE_INFINITY || v == NEGATIVE_INFINITY);
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}
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/**
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* Return the int bits of the specified <code>float</code>.
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* The result of this function can be used as the argument to
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* <code>Float.intBitsToFloat(long)</code> to obtain the
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* original <code>float</code> value.
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*
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* @param value the <code>float</code> to convert
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* @return the bits of the <code>float</code>.
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*/
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public static native int floatToIntBits (float value);
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/**
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* Return the int bits of the specified <code>float</code>.
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* The result of this function can be used as the argument to
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* <code>Float.intBitsToFloat(long)</code> to obtain the
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* original <code>float</code> value. The difference between
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* this function and <code>floatToIntBits</code> is that this
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* function does not collapse NaN values.
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*
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* @param value the <code>float</code> to convert
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* @return the bits of the <code>float</code>.
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*/
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public static native int floatToRawIntBits (float value);
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/**
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* Return the <code>float</code> represented by the long
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* bits specified.
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*
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* @param bits the long bits representing a <code>double</code>
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* @return the <code>float</code> represented by the bits.
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*/
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public static native float intBitsToFloat (int bits);
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/**
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* Returns 0 if the <code>float</code> value of the argument is
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* equal to the value of this <code>Float</code>. Returns a number
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* less than zero if the value of this <code>Float</code> is less
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* than the <code>Float</code> value of the argument, and returns a
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* number greater than zero if the value of this <code>Float</code>
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* is greater than the <code>float</code> value of the argument.
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* <br>
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* <code>Float.NaN</code> is greater than any number other than itself,
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* even <code>Float.POSITIVE_INFINITY</code>.
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* <br>
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* <code>0.0</code> is greater than <code>-0.0</code>.
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*
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* @param f the Float to compare to.
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* @return 0 if the <code>Float</code>s are the same, < 0 if this
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* <code>Float</code> is less than the <code>Float</code> in
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* in question, or > 0 if it is greater.
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*
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* @since 1.2
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*/
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public int compareTo (Float f)
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{
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return compare (value, f.value);
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}
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/**
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* Returns 0 if the first argument is equal to the second argument.
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* Returns a number less than zero if the first argument is less than the
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* second argument, and returns a number greater than zero if the first
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* argument is greater than the second argument.
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* <br>
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* <code>Float.NaN</code> is greater than any number other than itself,
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* even <code>Float.POSITIVE_INFINITY</code>.
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* <br>
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* <code>0.0</code> is greater than <code>-0.0</code>.
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*
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* @param x the first float to compare.
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* @param y the second float to compare.
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* @return 0 if the arguments are the same, < 0 if the
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* first argument is less than the second argument in
|
|
* in question, or > 0 if it is greater.
|
|
* @since 1.4
|
|
*/
|
|
public static int compare (float x, float y)
|
|
{
|
|
if (isNaN (x))
|
|
return isNaN (y) ? 0 : 1;
|
|
if (isNaN (y))
|
|
return -1;
|
|
// recall that 0.0 == -0.0, so we convert to infinities and try again
|
|
if (x == 0 && y == 0)
|
|
return (int) (1 / x - 1 / y);
|
|
if (x == y)
|
|
return 0;
|
|
|
|
return x > y ? 1 : -1;
|
|
}
|
|
|
|
/**
|
|
* Compares the specified <code>Object</code> to this <code>Float</code>
|
|
* if and only if the <code>Object</code> is an instanceof
|
|
* <code>Float</code>.
|
|
* Otherwise it throws a <code>ClassCastException</code>
|
|
*
|
|
* @param o the Object to compare to.
|
|
* @return 0 if the <code>Float</code>s are the same, < 0 if this
|
|
* <code>Float</code> is less than the <code>Float</code> in
|
|
* in question, or > 0 if it is greater.
|
|
* @throws ClassCastException if the argument is not a <code>Float</code>
|
|
*
|
|
* @since 1.2
|
|
*/
|
|
public int compareTo (Object o)
|
|
{
|
|
return compareTo ((Float) o);
|
|
}
|
|
}
|