double.java

gcc的组建

  /**
   * Return <code>true</code> if the <code>double</code> has a value
   * equal to either <code>NEGATIVE_INFINITY</code> or
   * <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>.
   *
   * @param v the <code>double</code> to compare
   * @return whether the argument is (-/+) infinity.
   */
  public static boolean isInfinite(double v)
  {
    return v == POSITIVE_INFINITY || v == NEGATIVE_INFINITY;
  }

  /**
   * Return <code>true</code> if the value of this <code>Double</code>
   * is the same as <code>NaN</code>, otherwise return <code>false</code>.
   *
   * @return whether this <code>Double</code> is <code>NaN</code>
   */
  public boolean isNaN()
  {
    return isNaN(value);
  }

  /**
   * Return <code>true</code> if the value of this <code>Double</code>
   * is the same as <code>NEGATIVE_INFINITY</code> or
   * <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>.
   *
   * @return whether this <code>Double</code> is (-/+) infinity
   */
  public boolean isInfinite()
  {
    return isInfinite(value);
  }

  /**
   * Convert the <code>double</code> value of this <code>Double</code>
   * to a <code>String</code>.  This method calls
   * <code>Double.toString(double)</code> to do its dirty work.
   *
   * @return the <code>String</code> representation
   * @see #toString(double)
   */
  public String toString()
  {
    return toString(value);
  }

  /**
   * Return the value of this <code>Double</code> as a <code>byte</code>.
   *
   * @return the byte value
   * @since 1.1
   */
  public byte byteValue()
  {
    return (byte) value;
  }

  /**
   * Return the value of this <code>Double</code> as a <code>short</code>.
   *
   * @return the short value
   * @since 1.1
   */
  public short shortValue()
  {
    return (short) value;
  }

  /**
   * Return the value of this <code>Double</code> as an <code>int</code>.
   *
   * @return the int value
   */
  public int intValue()
  {
    return (int) value;
  }

  /**
   * Return the value of this <code>Double</code> as a <code>long</code>.
   *
   * @return the long value
   */
  public long longValue()
  {
    return (long) value;
  }

  /**
   * Return the value of this <code>Double</code> as a <code>float</code>.
   *
   * @return the float value
   */
  public float floatValue()
  {
    return (float) value;
  }

  /**
   * Return the value of this <code>Double</code>.
   *
   * @return the double value
   */
  public double doubleValue()
  {
    return value;
  }

  /**
   * Return a hashcode representing this Object. <code>Double</code>'s hash
   * code is calculated by:<br>
   * <code>long v = Double.doubleToLongBits(doubleValue());<br>
   *    int hash = (int)(v^(v&gt;&gt;32))</code>.
   *
   * @return this Object's hash code
   * @see #doubleToLongBits(double)
   */
  public int hashCode()
  {
    long v = doubleToLongBits(value);
    return (int) (v ^ (v >>> 32));
  }

  /**
   * Returns <code>true</code> if <code>obj</code> is an instance of
   * <code>Double</code> and represents the same double value. Unlike comparing
   * two doubles with <code>==</code>, this treats two instances of
   * <code>Double.NaN</code> as equal, but treats <code>0.0</code> and
   * <code>-0.0</code> as unequal.
   *
   * <p>Note that <code>d1.equals(d2)</code> is identical to
   * <code>doubleToLongBits(d1.doubleValue()) ==
   *    doubleToLongBits(d2.doubleValue())</code>.
   *
   * @param obj the object to compare
   * @return whether the objects are semantically equal
   */
  public boolean equals(Object obj)
  {
    if (! (obj instanceof Double))
      return false;

    double d = ((Double) obj).value;

    // Avoid call to native method. However, some implementations, like gcj,
    // are better off using floatToIntBits(value) == floatToIntBits(f).
    // Check common case first, then check NaN and 0.
    if (value == d)
      return (value != 0) || (1 / value == 1 / d);
    return isNaN(value) && isNaN(d);
  }

  /**
   * Convert the double to the IEEE 754 floating-point "double format" bit
   * layout. Bit 63 (the most significant) is the sign bit, bits 62-52
   * (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0
   * (masked by 0x000fffffffffffffL) are the mantissa. This function
   * collapses all versions of NaN to 0x7ff8000000000000L. The result of this
   * function can be used as the argument to
   * <code>Double.longBitsToDouble(long)</code> to obtain the original
   * <code>double</code> value.
   *
   * @param value the <code>double</code> to convert
   * @return the bits of the <code>double</code>
   * @see #longBitsToDouble(long)
   */
  public static long doubleToLongBits(double value)
  {
    return VMDouble.doubleToLongBits(value);
  }

  /**
   * Convert the double to the IEEE 754 floating-point "double format" bit
   * layout. Bit 63 (the most significant) is the sign bit, bits 62-52
   * (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0
   * (masked by 0x000fffffffffffffL) are the mantissa. This function
   * leaves NaN alone, rather than collapsing to a canonical value. The
   * result of this function can be used as the argument to
   * <code>Double.longBitsToDouble(long)</code> to obtain the original
   * <code>double</code> value.
   *
   * @param value the <code>double</code> to convert
   * @return the bits of the <code>double</code>
   * @see #longBitsToDouble(long)
   */
  public static long doubleToRawLongBits(double value)
  {
    return VMDouble.doubleToRawLongBits(value);
  }

  /**
   * Convert the argument in IEEE 754 floating-point "double format" bit
   * layout to the corresponding float. Bit 63 (the most significant) is the
   * sign bit, bits 62-52 (masked by 0x7ff0000000000000L) represent the
   * exponent, and bits 51-0 (masked by 0x000fffffffffffffL) are the mantissa.
   * This function leaves NaN alone, so that you can recover the bit pattern
   * with <code>Double.doubleToRawLongBits(double)</code>.
   *
   * @param bits the bits to convert
   * @return the <code>double</code> represented by the bits
   * @see #doubleToLongBits(double)
   * @see #doubleToRawLongBits(double)
   */
  public static double longBitsToDouble(long bits)
  {
    return VMDouble.longBitsToDouble(bits);
  }

  /**
   * Compare two Doubles numerically by comparing their <code>double</code>
   * values. The result is positive if the first is greater, negative if the
   * second is greater, and 0 if the two are equal. However, this special
   * cases NaN and signed zero as follows: NaN is considered greater than
   * all other doubles, including <code>POSITIVE_INFINITY</code>, and positive
   * zero is considered greater than negative zero.
   *
   * @param d the Double to compare
   * @return the comparison
   * @since 1.2
   */
  public int compareTo(Double d)
  {
    return compare(value, d.value);
  }

  /**
   * Behaves like <code>compareTo(Double)</code> unless the Object
   * is not an <code>Double</code>.
   *
   * @param o the object to compare
   * @return the comparison
   * @throws ClassCastException if the argument is not a <code>Double</code>
   * @see #compareTo(Double)
   * @see Comparable
   * @since 1.2
   */
  public int compareTo(Object o)
  {
    return compare(value, ((Double) o).value);
  }

  /**
   * Behaves like <code>new Double(x).compareTo(new Double(y))</code>; in
   * other words this compares two doubles, special casing NaN and zero,
   * without the overhead of objects.
   *
   * @param x the first double to compare
   * @param y the second double to compare
   * @return the comparison
   * @since 1.4
   */
  public static int compare(double x, double y)
  {
    if (isNaN(x))
      return isNaN(y) ? 0 : 1;
    if (isNaN(y))
      return -1;
    // recall that 0.0 == -0.0, so we convert to infinites and try again
    if (x == 0 && y == 0)
      return (int) (1 / x - 1 / y);
    if (x == y)
      return 0;

    return x > y ? 1 : -1;
  }
}