integer.java

来自「gcc3.2.1源代码」· Java 代码 · 共 593 行 · 第 1/2 页

          {
            buffer[--i] = Character.forDigit(-(num + radix) % radix, radix);
            num = -(num / radix);
          }
      }
    else
      isNeg = false;

    do
      {
        buffer[--i] = Character.forDigit(num % radix, radix);
        num /= radix;
      }
    while (num > 0);

    if (isNeg)
      buffer[--i] = '-';

    return String.valueOf(buffer, i, 33-i);
  }

  /**
   * Creates a new <code>Integer</code> object using the <code>String</code>,
   * assuming a radix of 10.
   * @param s the <code>String</code> to convert.
   * @return the new <code>Integer</code>.
   * @see #Integer(java.lang.String)
   * @see #parseInt(java.lang.String)
   * @exception NumberFormatException thrown if the <code>String</code> 
   * cannot be parsed as an <code>int</code>.
   */
  public static Integer valueOf(String s) throws NumberFormatException
  {
    return new Integer(parseInt(s));
  }

  /**
   * Creates a new <code>Integer</code> object using the <code>String</code>
   * and specified radix (base).
   * @param s the <code>String</code> to convert.
   * @param radix the radix (base) to convert with.
   * @return the new <code>Integer</code>.
   * @see #parseInt(java.lang.String,int)
   * @exception NumberFormatException thrown if the <code>String</code> 
   * cannot be parsed as an <code>int</code>.
   */
  public static Integer valueOf(String s, int radix)
    throws NumberFormatException
  {
    return new Integer(parseInt(s, radix));
  }

  /**
   * Converts the specified <code>String</code> into an <code>int</code>.
   * This function assumes a radix of 10.
   *
   * @param s the <code>String</code> to convert
   * @return the <code>int</code> value of the <code>String</code>
   *         argument.
   * @exception NumberFormatException thrown if the <code>String</code> 
   * cannot be parsed as an <code>int</code>.
   */
  public static int parseInt(String s) throws NumberFormatException
  {
    return parseInt(s, 10);
  }

  /**
   * Converts the specified <code>String</code> into an <code>int</code>
   * using the specified radix (base).
   *
   * @param s the <code>String</code> to convert
   * @param radix the radix (base) to use in the conversion
   * @return the <code>String</code> argument converted to </code>int</code>.
   * @exception NumberFormatException thrown if the <code>String</code> 
   * cannot be parsed as a <code>int</code>.    
   */
  public static int parseInt(String str, int radix)
    throws NumberFormatException
  {
    final int len;

    if (str == null)
      throw new NumberFormatException ();

    if ((len = str.length()) == 0 ||
        radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
      throw new NumberFormatException();

    boolean isNeg = false;
    int index = 0;
    if (str.charAt(index) == '-')
      if (len > 1)
        {
          isNeg = true;
          index++;
        }
      else
        throw new NumberFormatException();

    return parseInt(str, index, len, isNeg, radix);
  }

  private static int parseInt(String str, int index, int len, boolean isNeg,
			      int radix)
    throws NumberFormatException
  {
    int val = 0;
    int digval;

    int max = MAX_VALUE / radix;
    // We can't directly write `max = (MAX_VALUE + 1) / radix'.
    // So instead we fake it.
    if (isNeg && MAX_VALUE % radix == radix - 1)
      ++max;

    for ( ; index < len; index++)
      {
	if (val < 0 || val > max)
	  throw new NumberFormatException();

        if ((digval = Character.digit(str.charAt(index), radix)) < 0)
          throw new NumberFormatException();

        // Throw an exception for overflow if result is negative.
	// However, we special-case the most negative value.
	val = val * radix + digval;
	if (val < 0 && (! isNeg || val != MIN_VALUE))
	  throw new NumberFormatException();
      }

    return isNeg ? -(val) : val;
  }

  /**
   * Convert the specified <code>String</code> into an <code>Integer</code>.
   * The <code>String</code> may represent decimal, hexadecimal, or 
   * octal numbers.
   *
   * The <code>String</code> argument is interpreted based on the leading
   * characters.  Depending on what the String begins with (after an optional
   * minus sign), the base will be interpreted differently:
   *
   * <table border=1>
   * <tr><th>Leading<br>Characters</th><th>Base</th></tr>
   * <tr><td>#</td><td>16</td></tr>
   * <tr><td>0x</td><td>16</td></tr>
   * <tr><td>0X</td><td>16</td></tr>
   * <tr><td>0</td><td>8</td></tr>
   * <tr><td>Anything<br>Else</td><td>10</td></tr>
   * </table>
   *
   * If the String starts with a minus sign the result is negated.
   *
   * @param str the <code>String</code> to interpret.
   * @return the value of the String as an <code>Integer</code>.
   * @exception NumberFormatException thrown if the <code>String</code> 
   * cannot be parsed as an <code>int</code>.    
   */
  public static Integer decode(String str) throws NumberFormatException
  {
    boolean isNeg = false;
    int index = 0;
    int radix = 10;
    final int len;

    if ((len = str.length()) == 0)
      throw new NumberFormatException("empty string");

    if (str.charAt(index) == '-')
      {
        // The minus sign should be followed by at least one more char
        if (len > 1)
          {
            isNeg = true;
            index++;
          }
        else
          throw new NumberFormatException();
      }

    if (str.charAt(index) == '#')
      {
        radix = 16;
        index++;
      }
    else if (str.charAt(index) == '0')
      {
        index++;

        // Check if str is just "0" or "-0"
        if (len == index)
          return new Integer(0);

        if (str.charAt(index) == 'x' || str.charAt(index) == 'X')
          {
            radix = 16;
            index++;
          }
        else
          radix = 8;
      }

    if (index >= len)
      throw new NumberFormatException("empty value");

    return new Integer(parseInt(str, index, len, isNeg, radix));
  }

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

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

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

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

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

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

  /**
   * Compare two Integers numerically by comparing their
   * <code>int</code> values.
   * @return a positive value if this <code>Integer</code> is greater
   * in value than the argument <code>Integer</code>; a negative value
   * if this <code>Integer</code> is smaller in value than the argument
   * <code>Integer</code>; and <code>0</code>, zero, if this
   * <code>Integer</code> is equal in value to the argument
   * <code>Integer</code>.  
   *
   * @since 1.2
   */
  public int compareTo(Integer i)
  {
    if (this.value == i.value)
      return 0;

    // Returns just -1 or 1 on inequality; doing math might overflow.
    if (this.value > i.value)
      return 1;

    return -1;
  }

  /**
   * Behaves like <code>compareTo(java.lang.Integer)</code> unless the Object
   * is not a <code>Integer</code>.  Then it throws a 
   * <code>ClassCastException</code>.
   * @exception ClassCastException if the argument is not a
   * <code>Integer</code>.
   *
   * @since 1.2
   */
  public int compareTo(Object o)
  {
    return compareTo((Integer)o);
  }
}