mathutils.java

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     * @return constant indicating type of Number to use in calculations
     */
    private static int findCalculationBase (Number op1, Number op2)
    {

        boolean op1Int = isInteger(op1);
        boolean op2Int = isInteger(op2);

        if ( (op1 instanceof BigDecimal || op2 instanceof BigDecimal) ||
             ( (!op1Int || !op2Int) && (op1 instanceof BigInteger || op2 instanceof BigInteger)) )
        {
            return BASE_BIGDECIMAL;
        }

        if (op1Int && op2Int) {
            if (op1 instanceof BigInteger || op2 instanceof BigInteger)
            {
                return BASE_BIGINTEGER;
            }
            return BASE_LONG;
        }

        if ((op1 instanceof Double) || (op2 instanceof Double))
        {
            return BASE_DOUBLE;
        }
        return BASE_FLOAT;
    }

    /**
     * Add two numbers and return the correct value / type.
     * Overflow detection is done for integer values (byte, short, int, long) only!
     * @param op1
     * @param op2
     * @return Addition result.
     */
    public static Number add (Number op1, Number op2)
    {

        int calcBase = findCalculationBase( op1, op2);
        switch (calcBase)
        {
            case BASE_BIGINTEGER:
                return toBigInteger( op1 ).add( toBigInteger( op2 ));
            case BASE_LONG:
                long l1 = op1.longValue();
                long l2 = op2.longValue();
                long result = l1+l2;

                // Overflow check
                if ((result ^ l1) < 0 && (result ^ l2) < 0)
                {
                    return toBigInteger( op1).add( toBigInteger( op2));
                }
                return wrapPrimitive( result, op1, op2);
            case BASE_FLOAT:
                return new Float (op1.floatValue()+op2.floatValue());
            case BASE_DOUBLE:
                return new Double (op1.doubleValue()+op2.doubleValue());

            // Default is BigDecimal operation
            default:
                return toBigDecimal( op1 ).add( toBigDecimal( op2 ));
        }
    }

    /**
     * Subtract two numbers and return the correct value / type.
     * Overflow detection is done for integer values (byte, short, int, long) only!
     * @param op1
     * @param op2
     * @return Subtraction result.
     */
    public static Number subtract (Number op1, Number op2) {

        int calcBase = findCalculationBase( op1, op2);
        switch (calcBase) {
            case BASE_BIGINTEGER:
                return toBigInteger( op1 ).subtract( toBigInteger( op2 ));
            case BASE_LONG:
                long l1 = op1.longValue();
                long l2 = op2.longValue();
                long result = l1-l2;

                // Overflow check
                if ((result ^ l1) < 0 && (result ^ ~l2) < 0) {
                    return toBigInteger( op1).subtract( toBigInteger( op2));
                }
                return wrapPrimitive( result, op1, op2);
            case BASE_FLOAT:
                return new Float (op1.floatValue()-op2.floatValue());
            case BASE_DOUBLE:
                return new Double (op1.doubleValue()-op2.doubleValue());

            // Default is BigDecimal operation
            default:
                return toBigDecimal( op1 ).subtract( toBigDecimal( op2 ));
        }
    }

    /**
     * Multiply two numbers and return the correct value / type.
     * Overflow detection is done for integer values (byte, short, int, long) only!
     * @param op1
     * @param op2
     * @return Multiplication result.
     */
    public static Number multiply (Number op1, Number op2) {

        int calcBase = findCalculationBase( op1, op2);
        switch (calcBase) {
            case BASE_BIGINTEGER:
                return toBigInteger( op1 ).multiply( toBigInteger( op2 ));
            case BASE_LONG:
                long l1 = op1.longValue();
                long l2 = op2.longValue();
                long result = l1*l2;

                // Overflow detection
                if ((l2 != 0) && (result / l2 != l1)) {
                    return toBigInteger( op1).multiply( toBigInteger( op2));
                }
                return wrapPrimitive( result, op1, op2);
            case BASE_FLOAT:
                return new Float (op1.floatValue()*op2.floatValue());
            case BASE_DOUBLE:
                return new Double (op1.doubleValue()*op2.doubleValue());

            // Default is BigDecimal operation
            default:
                return toBigDecimal( op1 ).multiply( toBigDecimal( op2 ));
        }
    }

    /**
     * Divide two numbers. The result will be returned as Integer-type if and only if
     * both sides of the division operator are Integer-types. Otherwise a Float, Double,
     * or BigDecimal will be returned.
     * @param op1
     * @param op2
     * @return Division result.
     */
    public static Number divide (Number op1, Number op2) {

        int calcBase = findCalculationBase( op1, op2);
        switch (calcBase) {
            case BASE_BIGINTEGER:
                BigInteger b1 = toBigInteger( op1 );
                BigInteger b2 = toBigInteger( op2 );
                return b1.divide( b2);

            case BASE_LONG:
                long l1 = op1.longValue();
                long l2 = op2.longValue();
                return wrapPrimitive( l1 / l2, op1, op2);

            case BASE_FLOAT:
                return new Float (op1.floatValue()/op2.floatValue());
            case BASE_DOUBLE:
                return new Double (op1.doubleValue()/op2.doubleValue());

            // Default is BigDecimal operation
            default:
                return toBigDecimal( op1 ).divide( toBigDecimal( op2 ), BigDecimal.ROUND_HALF_DOWN);
        }
    }

    /**
     * Modulo two numbers.
     * @param op1
     * @param op2
     * @return Modulo result.
     *
     * @throws ArithmeticException If at least one parameter is a BigDecimal
     */
    public static Number modulo (Number op1, Number op2) throws ArithmeticException {

        int calcBase = findCalculationBase( op1, op2);
        switch (calcBase) {
            case BASE_BIGINTEGER:
                return toBigInteger( op1 ).mod( toBigInteger( op2 ));
            case BASE_LONG:
                return wrapPrimitive( op1.longValue() % op2.longValue(), op1, op2);
            case BASE_FLOAT:
                return new Float (op1.floatValue() % op2.floatValue());
            case BASE_DOUBLE:
                return new Double (op1.doubleValue() % op2.doubleValue());

            // Default is BigDecimal operation
            default:
                throw new ArithmeticException( "Cannot calculate the modulo of BigDecimals.");
        }
    }

    /**
     * Compare two numbers.
     * @param op1
     * @param op2
     * @return 1 if n1 > n2, -1 if n1 < n2 and 0 if equal.
     */
    public static int compare (Number op1, Number op2) {

        int calcBase = findCalculationBase( op1, op2);
        switch (calcBase) {
            case BASE_BIGINTEGER:
                return toBigInteger( op1 ).compareTo( toBigInteger( op2 ));
            case BASE_LONG:
                long l1 = op1.longValue();
                long l2 = op2.longValue();
                if (l1 < l2) {
                    return -1;
                }
                if (l1 > l2) {
                    return 1;
                }
                return 0;
            case BASE_FLOAT:
                float f1 = op1.floatValue();
                float f2 = op2.floatValue();
                if (f1 < f2) {
                    return -1;
                }
                if (f1 > f2) {
                    return 1;
                }
                return 0;
            case BASE_DOUBLE:
                double d1 = op1.doubleValue();
                double d2 = op2.doubleValue();
                if (d1 < d2) {
                    return -1;
                }
                if (d1 > d2) {
                    return 1;
                }
                return 0;

            // Default is BigDecimal operation
            default:
                return toBigDecimal( op1 ).compareTo( toBigDecimal ( op2 ));
        }
    }
}