bigdecimal.java

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     * @param val value of the BigDecimal.
     * @return a BigDecimal whose value is <tt>val</tt>.
     */
    public static BigDecimal valueOf(long val) {
	return valueOf(val, 0);
    }


    // Arithmetic Operations

    /**
     * Returns a BigDecimal whose value is <tt>(this + val)</tt>, and whose
     * scale is <tt>max(this.scale(), val.scale())</tt>.
     *
     * @param  val value to be added to this BigDecimal.
     * @return <tt>this + val</tt>
     */
    public BigDecimal add(BigDecimal val){
	BigDecimal arg[] = new BigDecimal[2];
	arg[0] = this;	arg[1] = val;
	matchScale(arg);
	return new BigDecimal(arg[0].intVal.add(arg[1].intVal), arg[0].scale);
    }

    /**
     * Returns a BigDecimal whose value is <tt>(this - val)</tt>, and whose
     * scale is <tt>max(this.scale(), val.scale())</tt>.
     *
     * @param  val value to be subtracted from this BigDecimal.
     * @return <tt>this - val</tt>
     */
    public BigDecimal subtract(BigDecimal val){
	BigDecimal arg[] = new BigDecimal[2];
	arg[0] = this;	arg[1] = val;
	matchScale(arg);
	return new BigDecimal(arg[0].intVal.subtract(arg[1].intVal),
			      arg[0].scale);
    }

    /**
     * Returns a BigDecimal whose value is <tt>(this * val)</tt>, and whose
     * scale is <tt>(this.scale() + val.scale())</tt>.
     *
     * @param  val value to be multiplied by this BigDecimal.
     * @return <tt>this * val</tt>
     */
    public BigDecimal multiply(BigDecimal val){
	return new BigDecimal(intVal.multiply(val.intVal), scale+val.scale);
    }

    /**
     * Returns a BigDecimal whose value is <tt>(this / val)</tt>, and whose
     * scale is as specified.  If rounding must be performed to generate a
     * result with the specified scale, the specified rounding mode is
     * applied.
     *
     * @param  val value by which this BigDecimal is to be divided.
     * @param  scale scale of the BigDecimal quotient to be returned.
     * @param  roundingMode rounding mode to apply.
     * @return <tt>this / val</tt>
     * @throws ArithmeticException <tt>val</tt> is zero, <tt>scale</tt> is
     *	       negative, or <tt>roundingMode==ROUND_UNNECESSARY</tt> and
     *	       the specified scale is insufficient to represent the result
     *	       of the division exactly.
     * @throws IllegalArgumentException <tt>roundingMode</tt> does not
     *	       represent a valid rounding mode.
     * @see    #ROUND_UP
     * @see    #ROUND_DOWN
     * @see    #ROUND_CEILING
     * @see    #ROUND_FLOOR
     * @see    #ROUND_HALF_UP
     * @see    #ROUND_HALF_DOWN
     * @see    #ROUND_HALF_EVEN
     * @see    #ROUND_UNNECESSARY
     */
    public BigDecimal divide(BigDecimal val, int scale, int roundingMode) {
	if (scale < 0)
	    throw new ArithmeticException("Negative scale");
	if (roundingMode < ROUND_UP || roundingMode > ROUND_UNNECESSARY)
	    throw new IllegalArgumentException("Invalid rounding mode");

	/*
	 * Rescale dividend or divisor (whichever can be "upscaled" to
	 * produce correctly scaled quotient).
	 */
	BigDecimal dividend, divisor;
	if (scale + val.scale >= this.scale) {
	    dividend = this.setScale(scale + val.scale);
	    divisor = val;
	} else {
	    dividend = this;
	    divisor = val.setScale(this.scale - scale);
	}

	/* Do the division and return result if it's exact */
	BigInteger i[] = dividend.intVal.divideAndRemainder(divisor.intVal);
	BigInteger q = i[0], r = i[1];
	if (r.signum() == 0)
	    return new BigDecimal(q, scale);
	else if (roundingMode == ROUND_UNNECESSARY) /* Rounding prohibited */
	    throw new ArithmeticException("Rounding necessary");

	/* Round as appropriate */
	int signum = dividend.signum() * divisor.signum(); /* Sign of result */
	boolean increment;
	if (roundingMode == ROUND_UP) {		    /* Away from zero */
	    increment = true;
	} else if (roundingMode == ROUND_DOWN) {    /* Towards zero */
	    increment = false;
	} else if (roundingMode == ROUND_CEILING) { /* Towards +infinity */
	    increment = (signum > 0);
	} else if (roundingMode == ROUND_FLOOR) {   /* Towards -infinity */
	    increment = (signum < 0);
	} else { /* Remaining modes based on nearest-neighbor determination */
	    int cmpFracHalf = r.abs().multiply(BigInteger.valueOf(2)).
					 compareTo(divisor.intVal.abs());
	    if (cmpFracHalf < 0) {	   /* We're closer to higher digit */
		increment = false;
	    } else if (cmpFracHalf > 0) {  /* We're closer to lower digit */
		increment = true;
	    } else { 			   /* We're dead-center */
		if (roundingMode == ROUND_HALF_UP)
		    increment = true;
		else if (roundingMode == ROUND_HALF_DOWN)
		    increment = false;
		else  /* roundingMode == ROUND_HALF_EVEN */
		    increment = q.testBit(0);	/* true iff q is odd */
	    }
	}
	return (increment
		? new BigDecimal(q.add(BigInteger.valueOf(signum)), scale)
		: new BigDecimal(q, scale));
    }

    /**
     * Returns a BigDecimal whose value is <tt>(this / val)</tt>, and whose
     * scale is <tt>this.scale()</tt>.  If rounding must be performed to
     * generate a result with the given scale, the specified rounding mode is
     * applied.
     *
     * @param  val value by which this BigDecimal is to be divided.
     * @param  roundingMode rounding mode to apply.
     * @return <tt>this / val</tt>
     * @throws ArithmeticException <tt>val==0</tt>, or
     * 	       <tt>roundingMode==ROUND_UNNECESSARY</tt> and
     *	       <tt>this.scale()</tt> is insufficient to represent the result
     *	       of the division exactly. 
     * @throws IllegalArgumentException <tt>roundingMode</tt> does not
     *	       represent a valid rounding mode.
     * @see    #ROUND_UP
     * @see    #ROUND_DOWN
     * @see    #ROUND_CEILING
     * @see    #ROUND_FLOOR
     * @see    #ROUND_HALF_UP
     * @see    #ROUND_HALF_DOWN
     * @see    #ROUND_HALF_EVEN
     * @see    #ROUND_UNNECESSARY
     */
    public BigDecimal divide(BigDecimal val, int roundingMode) {
	    return this.divide(val, scale, roundingMode);
    }

   /**
    * Returns a BigDecimal whose value is the absolute value of this
    * BigDecimal, and whose scale is <tt>this.scale()</tt>.
    *
    * @return <tt>abs(this)</tt>
    */
    public BigDecimal abs(){
	return (signum() < 0 ? negate() : this);
    }

    /**
     * Returns a BigDecimal whose value is <tt>(-this)</tt>, and whose scale
     * is <tt>this.scale()</tt>.
     *
     * @return <tt>-this</tt>
     */
    public BigDecimal negate(){
	return new BigDecimal(intVal.negate(), scale);
    }

    /**
     * Returns the signum function of this BigDecimal.
     *
     * @return -1, 0 or 1 as the value of this BigDecimal is negative, zero or
     *	       positive.
     */
    public int signum(){
	return intVal.signum();
    }

    /**
     * Returns the <i>scale</i> of this BigDecimal.  (The scale is the number
     * of digits to the right of the decimal point.)
     *
     * @return the scale of this BigDecimal.
     */
    public int scale() {
	return scale;
    }

    /**
     * Returns a BigInteger whose value is the <i>unscaled value</i> of this
     * BigDecimal.  (Computes <tt>(this * 10<sup>this.scale()</sup>)</tt>.)
     *
     * @return the unscaled value of this BigDecimal.
     * @since   1.2
     */
    public BigInteger unscaledValue() {
        return intVal;
    }


    // Rounding Modes

    /**
     * Rounding mode to round away from zero.  Always increments the
     * digit prior to a non-zero discarded fraction.  Note that this rounding
     * mode never decreases the magnitude of the calculated value.
     */
    public final static int ROUND_UP = 		 0;

    /**
     * Rounding mode to round towards zero.  Never increments the digit
     * prior to a discarded fraction (i.e., truncates).  Note that this
     * rounding mode never increases the magnitude of the calculated value.
     */
    public final static int ROUND_DOWN = 	 1;

    /**
     * Rounding mode to round towards positive infinity.  If the
     * BigDecimal is positive, behaves as for <tt>ROUND_UP</tt>; if negative, 
     * behaves as for <tt>ROUND_DOWN</tt>.  Note that this rounding mode never
     * decreases the calculated value.
     */
    public final static int ROUND_CEILING = 	 2;

    /**
     * Rounding mode to round towards negative infinity.  If the
     * BigDecimal is positive, behave as for <tt>ROUND_DOWN</tt>; if negative,
     * behave as for <tt>ROUND_UP</tt>.  Note that this rounding mode never
     * increases the calculated value.
     */
    public final static int ROUND_FLOOR = 	 3;

    /**
     * Rounding mode to round towards "nearest neighbor" unless both
     * neighbors are equidistant, in which case round up.
     * Behaves as for <tt>ROUND_UP</tt> if the discarded fraction is &gt;= .5;
     * otherwise, behaves as for <tt>ROUND_DOWN</tt>.  Note that this is the
     * rounding mode that most of us were taught in grade school.
     */
    public final static int ROUND_HALF_UP = 	 4;

    /**
     * Rounding mode to round towards "nearest neighbor" unless both
     * neighbors are equidistant, in which case round down.
     * Behaves as for <tt>ROUND_UP</tt> if the discarded fraction is &gt; .5;
     * otherwise, behaves as for <tt>ROUND_DOWN</tt>.
     */
    public final static int ROUND_HALF_DOWN = 	 5;

    /**
     * Rounding mode to round towards the "nearest neighbor" unless both
     * neighbors are equidistant, in which case, round towards the even
     * neighbor.  Behaves as for ROUND_HALF_UP if the digit to the left of the
     * discarded fraction is odd; behaves as for ROUND_HALF_DOWN if it's even.
     * Note that this is the rounding mode that minimizes cumulative error
     * when applied repeatedly over a sequence of calculations.
     */
    public final static int ROUND_HALF_EVEN = 	 6;

    /**
     * Rounding mode to assert that the requested operation has an exact
     * result, hence no rounding is necessary.  If this rounding mode is
     * specified on an operation that yields an inexact result, an
     * <tt>ArithmeticException</tt> is thrown.
     */
    public final static int ROUND_UNNECESSARY =  7;


    // Scaling/Rounding Operations

    /**
     * Returns a BigDecimal whose scale is the specified value, and whose
     * unscaled value is determined by multiplying or dividing this
     * BigDecimal's unscaled value by the appropriate power of ten to maintain
     * its overall value.  If the scale is reduced by the operation, the
     * unscaled value must be divided (rather than multiplied), and the value
     * may be changed; in this case, the specified rounding mode is applied to
     * the division.
     * <p>
     * Note that since BigDecimal objects are immutable, calls of this
     * method do <i>not</i> result in the original object being
     * modified, contrary to the usual convention of having methods
     * named <code>set<i>X</i></code> mutate field
     * <code><i>X</i></code>.  Instead, <code>setScale</code> returns
     * an object with the proper scale; the returned object may or may
     * not be newly allocated.
     *
     * @param  scale scale of the BigDecimal value to be returned.
     * @param  roundingMode The rounding mode to apply.
     * @return a BigDecimal whose scale is the specified value, and whose
     *	       unscaled value is determined by multiplying or dividing this
     * 	       BigDecimal's unscaled value by the appropriate power of ten to
     *	       maintain its overall value.
     * @throws ArithmeticException <tt>scale</tt> is negative, or
     * 	       <tt>roundingMode==ROUND_UNNECESSARY</tt> and the specified
     *	       scaling operation would require rounding.
     * @throws IllegalArgumentException <tt>roundingMode</tt> does not
     *	       represent a valid rounding mode.
     * @see    #ROUND_UP
     * @see    #ROUND_DOWN
     * @see    #ROUND_CEILING
     * @see    #ROUND_FLOOR
     * @see    #ROUND_HALF_UP
     * @see    #ROUND_HALF_DOWN
     * @see    #ROUND_HALF_EVEN
     * @see    #ROUND_UNNECESSARY
     */
    public BigDecimal setScale(int scale, int roundingMode) {
	if (scale < 0)
	    throw new ArithmeticException("Negative scale");
	if (roundingMode < ROUND_UP || roundingMode > ROUND_UNNECESSARY)
	    throw new IllegalArgumentException("Invalid rounding mode");

	/* Handle the easy cases */
	if (scale == this.scale)
	    return this;
	else if (scale > this.scale)
	    return new BigDecimal(timesTenToThe(intVal, scale-this.scale),
				  scale);
	else /* scale < this.scale */
	    return divide(valueOf(1), scale, roundingMode);
    }

    /**
     * Returns a BigDecimal whose scale is the specified value, and whose
     * value is numerically equal to this BigDecimal's.  Throws an
     * ArithmeticException if this is not possible.  This call is typically
     * used to increase the scale, in which case it is guaranteed that there
     * exists a BigDecimal of the specified scale and the correct value.  The
     * call can also be used to reduce the scale if the caller knows that the
     * BigDecimal has sufficiently many zeros at the end of its fractional
     * part (i.e., factors of ten in its integer value) to allow for the
     * rescaling without loss of precision.
     * <p>
     * This method returns the same result as the two argument version
     * of setScale, but saves the caller the trouble of specifying a
     * rounding mode in cases where it is irrelevant.
     * <p>
     * Note that since BigDecimal objects are immutable, calls of this
     * method do <i>not</i> result in the original object being
     * modified, contrary to the usual convention of having methods
     * named <code>set<i>X</i></code> mutate field
     * <code><i>X</i></code>.  Instead, <code>setScale</code> returns
     * an object with the proper scale; the returned object may or may
     * not be newly allocated.
     *
     * @param  scale scale of the BigDecimal value to be returned.
     * @return a BigDecimal whose scale is the specified value, and whose
     *	       unscaled value is determined by multiplying or dividing this
     * 	       BigDecimal's unscaled value by the appropriate power of ten to