BigDecimal JDK 1.6)

Description

public class BigDecimal

Immutable, arbitrary-precision signed decimal numbers.

Immutable, arbitrary-precision signed decimal numbers. A BigDecimal consists of an arbitrary precision integer unscaled value and a 32-bit integer scale. If zero or positive, the scale is the number of digits to the right of the decimal point. If negative, the unscaled value of the number is multiplied by ten to the power of the negation of the scale. The value of the number represented by the BigDecimal is therefore (unscaledValue × 10^-scale).

The BigDecimal class provides operations for arithmetic, scale manipulation, rounding, comparison, hashing, and format conversion. The BigDecimal.toString() method provides a canonical representation of a BigDecimal.

The BigDecimal class gives its user complete control over rounding behavior. If no rounding mode is specified and the exact result cannot be represented, an exception is thrown; otherwise, calculations can be carried out to a chosen precision and rounding mode by supplying an appropriate MathContext object to the operation. In either case, eight rounding modes are provided for the control of rounding. Using the integer fields in this class (such as BigDecimal.ROUND_HALF_UP) to represent rounding mode is largely obsolete; the enumeration values of the RoundingMode enum, (such as RoundingMode.HALF_UP) should be used instead.

When a MathContext object is supplied with a precision setting of 0 (for example, MathContext.UNLIMITED), arithmetic operations are exact, as are the arithmetic methods which take no MathContext object. (This is the only behavior that was supported in releases prior to 5.) As a corollary of computing the exact result, the rounding mode setting of a MathContext object with a precision setting of 0 is not used and thus irrelevant. In the case of divide, the exact quotient could have an infinitely long decimal expansion; for example, 1 divided by 3. If the quotient has a nonterminating decimal expansion and the operation is specified to return an exact result, an ArithmeticException is thrown. Otherwise, the exact result of the division is returned, as done for other operations.

When the precision setting is not 0, the rules of BigDecimal arithmetic are broadly compatible with selected modes of operation of the arithmetic defined in ANSI X3.274-1996 and ANSI X3.274-1996/AM 1-2000 (section 7.4). Unlike those standards, BigDecimal includes many rounding modes, which were mandatory for division in BigDecimal releases prior to 5. Any conflicts between these ANSI standards and the BigDecimal specification are resolved in favor of BigDecimal.

Since the same numerical value can have different representations (with different scales), the rules of arithmetic and rounding must specify both the numerical result and the scale used in the result's representation.

In general the rounding modes and precision setting determine how operations return results with a limited number of digits when the exact result has more digits (perhaps infinitely many in the case of division) than the number of digits returned. First, the total number of digits to return is specified by the MathContext's precision setting; this determines the result's precision. The digit count starts from the leftmost nonzero digit of the exact result. The rounding mode determines how any discarded trailing digits affect the returned result.

For all arithmetic operators , the operation is carried out as though an exact intermediate result were first calculated and then rounded to the number of digits specified by the precision setting (if necessary), using the selected rounding mode. If the exact result is not returned, some digit positions of the exact result are discarded. When rounding increases the magnitude of the returned result, it is possible for a new digit position to be created by a carry propagating to a leading "9" digit. For example, rounding the value 999.9 to three digits rounding up would be numerically equal to one thousand, represented as 100×10¹. In such cases, the new "1" is the leading digit position of the returned result.

Besides a logical exact result, each arithmetic operation has a preferred scale for representing a result. The preferred scale for each operation is listed in the table below.

Preferred Scales for Results of Arithmetic Operations

Operation Preferred Scale of Result

Add max(addend.scale(), augend.scale())
Subtract max(minuend.scale(), subtrahend.scale())
Multiply multiplier.scale() + multiplicand.scale()
Divide dividend.scale() - divisor.scale()
These scales are the ones used by the methods which return exact arithmetic results; except that an exact divide may have to use a larger scale since the exact result may have more digits. For example, 1/32 is 0.03125.

Preferred Scales for Results of Arithmetic Operations
Operation	Preferred Scale of Result
Add	max(addend.scale(), augend.scale())
Subtract	max(minuend.scale(), subtrahend.scale())
Multiply	multiplier.scale() + multiplicand.scale()
Divide	dividend.scale() - divisor.scale()

Before rounding, the scale of the logical exact intermediate result is the preferred scale for that operation. If the exact numerical result cannot be represented in precision digits, rounding selects the set of digits to return and the scale of the result is reduced from the scale of the intermediate result to the least scale which can represent the precision digits actually returned. If the exact result can be represented with at most precision digits, the representation of the result with the scale closest to the preferred scale is returned. In particular, an exactly representable quotient may be represented in fewer than precision digits by removing trailing zeros and decreasing the scale. For example, rounding to three digits using the floor rounding mode,
19/100 = 0.19 // integer=19, scale=2
but
21/110 = 0.190 // integer=190, scale=3

Note that for add, subtract, and multiply, the reduction in scale will equal the number of digit positions of the exact result which are discarded. If the rounding causes a carry propagation to create a new high-order digit position, an additional digit of the result is discarded than when no new digit position is created.

Other methods may have slightly different rounding semantics. For example, the result of the pow method using the specified algorithm can occasionally differ from the rounded mathematical result by more than one unit in the last place, one ulp.

Two types of operations are provided for manipulating the scale of a BigDecimal: scaling/rounding operations and decimal point motion operations. Scaling/rounding operations (setScale and round) return a BigDecimal whose value is approximately (or exactly) equal to that of the operand, but whose scale or precision is the specified value; that is, they increase or decrease the precision of the stored number with minimal effect on its value. Decimal point motion operations (movePointLeft and movePointRight) return a BigDecimal created from the operand by moving the decimal point a specified distance in the specified direction.

For the sake of brevity and clarity, pseudo-code is used throughout the descriptions of BigDecimal methods. The pseudo-code expression (i + j) is shorthand for "a BigDecimal whose value is that of the BigDecimal i added to that of the BigDecimal j." The pseudo-code expression (i == j) is shorthand for "true if and only if the BigDecimal i represents the same value as the BigDecimal j." Other pseudo-code expressions are interpreted similarly. Square brackets are used to represent the particular BigInteger and scale pair defining a BigDecimal value; for example [19, 2] is the BigDecimal numerically equal to 0.19 having a scale of 2.

Note: care should be exercised if BigDecimal objects are used as keys in a SortedMap or elements in a SortedSet since BigDecimal's natural ordering is inconsistent with equals. See Comparable, SortedMap or SortedSet for more information.

All methods and constructors for this class throw NullPointerException when passed a null object reference for any input parameter.

See also: BigInteger MathContext RoundingMode SortedMap SortedSet

Constructors

public BigDecimal (BigInteger val)

Translates a BigInteger into a BigDecimal.

public BigDecimal (BigInteger unscaledVal, int scale)

Translates a BigInteger unscaled value and an int scale into a BigDecimal.

public BigDecimal (BigInteger unscaledVal, int scale, MathContext mc)

Translates a BigInteger unscaled value and an int scale into a BigDecimal, with rounding according to the context settings.

private BigDecimal (BigInteger intVal, long val, int scale)

Trusted internal constructor

public BigDecimal (BigInteger val, MathContext mc)

Translates a BigInteger into a BigDecimal rounding according to the context settings.

public BigDecimal (char[] in)

Translates a character array representation of a BigDecimal into a BigDecimal, accepting the same sequence of characters as the BigDecimal.BigDecimal(String) constructor.

public BigDecimal (char[] in, int offset, int len)

Translates a character array representation of a BigDecimal into a BigDecimal, accepting the same sequence of characters as the BigDecimal.BigDecimal(String) constructor, while allowing a sub-array to be specified.

public BigDecimal (char[] in, int offset, int len, MathContext mc)

public BigDecimal (char[] in, MathContext mc)

public BigDecimal (double val)

Translates a double into a BigDecimal which is the exact decimal representation of the double's binary floating-point value.

public BigDecimal (double val, MathContext mc)

Translates a double into a BigDecimal, with rounding according to the context settings.

public BigDecimal (int val)

Translates an int into a BigDecimal.

public BigDecimal (int val, MathContext mc)

Translates an int into a BigDecimal, with rounding according to the context settings.

public BigDecimal (long val)

Translates a long into a BigDecimal.

private BigDecimal (long val, int scale)

Trusted internal constructor

public BigDecimal (long val, MathContext mc)

Translates a long into a BigDecimal, with rounding according to the context settings.

public BigDecimal (String val)

Translates the string representation of a BigDecimal into a BigDecimal.

Translates the string representation of a BigDecimal into a BigDecimal. The string representation consists of an optional sign, '+' ('\u002B') or '-' ('\u002D'), followed by a sequence of zero or more decimal digits ("the integer"), optionally followed by a fraction, optionally followed by an exponent.

The fraction consists of a decimal point followed by zero or more decimal digits. The string must contain at least one digit in either the integer or the fraction. The number formed by the sign, the integer and the fraction is referred to as the significand.

The exponent consists of the character 'e' ('\u0065') or 'E' ('\u0045') followed by one or more decimal digits. The value of the exponent must lie between -Integer.MAX_VALUE (Integer.MIN_VALUE+1) and Integer.MAX_VALUE, inclusive.

More formally, the strings this constructor accepts are described by the following grammar:

BigDecimalString:
Sign_opt Significand Exponent_opt

Sign:
+
-

Significand:
IntegerPart . FractionPart_opt
. FractionPart
IntegerPart

IntegerPart:
Digits

FractionPart:
Digits

Exponent:
ExponentIndicator SignedInteger

ExponentIndicator:
e
E

SignedInteger:
Sign_opt Digits

Digits:
Digit
Digits Digit

Digit:
any character for which Character.isDigit(char) returns true, including 0, 1, 2 ...

The scale of the returned BigDecimal will be the number of digits in the fraction, or zero if the string contains no decimal point, subject to adjustment for any exponent; if the string contains an exponent, the exponent is subtracted from the scale. The value of the resulting scale must lie between Integer.MIN_VALUE and Integer.MAX_VALUE, inclusive.

The character-to-digit mapping is provided by Character.digit(char, int) set to convert to radix 10. The String may not contain any extraneous characters (whitespace, for example).

Examples:
The value of the returned BigDecimal is equal to significand × 10^exponent. For each string on the left, the resulting representation [BigInteger, scale] is shown on the right.

 "0"            [0,0]
 "0.00"         [0,2]
 "123"          [123,0]
 "-123"         [-123,0]
 "1.23E3"       [123,-1]
 "1.23E+3"      [123,-1]
 "12.3E+7"      [123,-6]
 "12.0"         [120,1]
 "12.3"         [123,1]
 "0.00123"      [123,5]
 "-1.23E-12"    [-123,14]
 "1234.5E-4"    [12345,5]
 "0E+7"         [0,-7]
 "-0"           [0,0]

Note: For values other than float and double NaN and ±Infinity, this constructor is compatible with the values returned by Float.toString(float) and Double.toString(double). This is generally the preferred way to convert a float or double into a BigDecimal, as it doesn't suffer from the unpredictability of the BigDecimal.BigDecimal(double) constructor.
Parameters:
- val - String representation of BigDecimal.
Throws:
- NumberFormatException - if val is not a valid representation of a BigDecimal.

public BigDecimal (String val, MathContext mc)

Translates the string representation of a BigDecimal into a BigDecimal, accepting the same strings as the BigDecimal.BigDecimal(String) constructor, with rounding according to the context settings.

Methods

Hide/Show inherited methods

public BigDecimal abs ()

Returns a BigDecimal whose value is the absolute value of this BigDecimal, and whose scale is this.scale().

public BigDecimal abs (MathContext mc)

Returns a BigDecimal whose value is the absolute value of this BigDecimal, with rounding according to the context settings.

public BigDecimal add (BigDecimal augend)

Returns a BigDecimal whose value is (this + augend), and whose scale is max(this.scale(), augend.scale()).

public BigDecimal add (BigDecimal augend, MathContext mc)

Returns a BigDecimal whose value is (this + augend), with rounding according to the context settings.

public byte byteValue () [Inherited From Number]

Returns the value of the specified number as a byte.

Returns the value of the specified number as a byte.
This may involve rounding or truncation.
Returns: the numeric value represented by this object after conversion to type byte.
Since: JDK1.1

public byte byteValueExact ()

Converts this BigDecimal to a byte, checking for lost information.

public int compareTo (BigDecimal val)

Compares this BigDecimal with the specified BigDecimal.

public BigDecimal divide (BigDecimal divisor)

Returns a BigDecimal whose value is (this / divisor), and whose preferred scale is (this.scale() - divisor.scale()); if the exact quotient cannot be represented (because it has a non-terminating decimal expansion) an ArithmeticException is thrown.

public BigDecimal divide (BigDecimal divisor, int roundingMode)

Returns a BigDecimal whose value is (this / divisor), and whose scale is this.scale().

public BigDecimal divide (BigDecimal divisor, int scale, int roundingMode)

Returns a BigDecimal whose value is (this / divisor), and whose scale is as specified.

public BigDecimal divide (BigDecimal divisor, int scale, RoundingMode roundingMode)

Returns a BigDecimal whose value is (this / divisor), and whose scale is as specified.

public BigDecimal divide (BigDecimal divisor, MathContext mc)

Returns a BigDecimal whose value is (this / divisor), with rounding according to the context settings.

public BigDecimal divide (BigDecimal divisor, RoundingMode roundingMode)

Returns a BigDecimal whose value is (this / divisor), and whose scale is this.scale().

public BigDecimal divideAndRemainder (BigDecimal divisor)

Returns a two-element BigDecimal array containing the result of divideToIntegralValue followed by the result of remainder on the two operands.

public BigDecimal divideAndRemainder (BigDecimal divisor, MathContext mc)

Returns a two-element BigDecimal array containing the result of divideToIntegralValue followed by the result of remainder on the two operands calculated with rounding according to the context settings.

public BigDecimal divideToIntegralValue (BigDecimal divisor)

Returns a BigDecimal whose value is the integer part of the quotient (this / divisor) rounded down.

Returns a BigDecimal whose value is the integer part
of the quotient (this / divisor) rounded down. The
preferred scale of the result is

(this.scale() -
 divisor.scale())

.
Returns: The integer part of this / divisor.
Parameters:
- divisor - value by which this BigDecimal is to be divided.
Throws:
- ArithmeticException - if divisor==0
Since: 1.5

public BigDecimal divideToIntegralValue (BigDecimal divisor, MathContext mc)

Returns a BigDecimal whose value is the integer part of (this / divisor).

Returns a BigDecimal whose value is the integer part
of (this / divisor). Since the integer part of the
exact quotient does not depend on the rounding mode, the
rounding mode does not affect the values returned by this
method. The preferred scale of the result is
(this.scale() - divisor.scale()). An
ArithmeticException is thrown if the integer part of
the exact quotient needs more than mc.precision
digits.
Returns: The integer part of this / divisor.
Parameters:
- divisor - value by which this BigDecimal is to be divided.
- mc - the context to use.
Throws:
- ArithmeticException - if divisor==0
- ArithmeticException - if mc.precision > 0 and the result requires a precision of more than mc.precision digits.
Since: 1.5

public double doubleValue () [Specified in Number]

Converts this BigDecimal to a double.

public boolean equals (Object x)

Compares this BigDecimal with the specified Object for equality.

public float floatValue () [Specified in Number]

Converts this BigDecimal to a float.

public int hashCode ()

Returns the hash code for this BigDecimal.

public int intValue () [Specified in Number]

Converts this BigDecimal to an int.

public int intValueExact ()

Converts this BigDecimal to an int, checking for lost information.

public long longValue () [Specified in Number]

Converts this BigDecimal to a long.

public long longValueExact ()

Converts this BigDecimal to a long, checking for lost information.

public BigDecimal max (BigDecimal val)

Returns the maximum of this BigDecimal and val.

public BigDecimal min (BigDecimal val)

Returns the minimum of this BigDecimal and val.

public BigDecimal movePointLeft (int n)

Returns a BigDecimal which is equivalent to this one with the decimal point moved n places to the left.

public BigDecimal movePointRight (int n)

Returns a BigDecimal which is equivalent to this one with the decimal point moved n places to the right.

public BigDecimal multiply (BigDecimal multiplicand)

Returns a BigDecimal whose value is (this × multiplicand), and whose scale is (this.scale() + multiplicand.scale()).

public BigDecimal multiply (BigDecimal multiplicand, MathContext mc)

Returns a BigDecimal whose value is (this × multiplicand), with rounding according to the context settings.

public BigDecimal negate ()

Returns a BigDecimal whose value is (-this), and whose scale is this.scale().

public BigDecimal negate (MathContext mc)

Returns a BigDecimal whose value is (-this), with rounding according to the context settings.

public BigDecimal plus ()

Returns a BigDecimal whose value is (+this), and whose scale is this.scale().

public BigDecimal plus (MathContext mc)

Returns a BigDecimal whose value is (+this), with rounding according to the context settings.

public BigDecimal pow (int n)

Returns a BigDecimal whose value is (thisⁿ), The power is computed exactly, to unlimited precision.

public BigDecimal pow (int n, MathContext mc)

Returns a BigDecimal whose value is (thisⁿ).

public int precision ()

Returns the precision of this BigDecimal.

public BigDecimal remainder (BigDecimal divisor)

Returns a BigDecimal whose value is (this % divisor).

public BigDecimal remainder (BigDecimal divisor, MathContext mc)

Returns a BigDecimal whose value is (this % divisor), with rounding according to the context settings.

public BigDecimal round (MathContext mc)

Returns a BigDecimal rounded according to the MathContext settings.

public int scale ()

Returns the scale of this BigDecimal.

public BigDecimal scaleByPowerOfTen (int n)

Returns a BigDecimal whose numerical value is equal to (this * 10ⁿ).

public BigDecimal setScale (int newScale)

Returns a BigDecimal whose scale is the specified value, and whose value is numerically equal to this BigDecimal's.

public BigDecimal setScale (int newScale, int roundingMode)

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.

public BigDecimal setScale (int newScale, RoundingMode roundingMode)

public short shortValue () [Inherited From Number]

Returns the value of the specified number as a short.

Returns the value of the specified number as a short.
This may involve rounding or truncation.
Returns: the numeric value represented by this object after conversion to type short.
Since: JDK1.1

public short shortValueExact ()

Converts this BigDecimal to a short, checking for lost information.

public int signum ()

Returns the signum function of this BigDecimal.

public BigDecimal stripTrailingZeros ()

Returns a BigDecimal which is numerically equal to this one but with any trailing zeros removed from the representation.

public BigDecimal subtract (BigDecimal subtrahend)

Returns a BigDecimal whose value is (this - subtrahend), and whose scale is max(this.scale(), subtrahend.scale()).

public BigDecimal subtract (BigDecimal subtrahend, MathContext mc)

Returns a BigDecimal whose value is (this - subtrahend), with rounding according to the context settings.

public BigInteger toBigInteger ()

Converts this BigDecimal to a BigInteger.

public BigInteger toBigIntegerExact ()

Converts this BigDecimal to a BigInteger, checking for lost information.

public String toEngineeringString ()

Returns a string representation of this BigDecimal, using engineering notation if an exponent is needed.

public String toPlainString ()

Returns a string representation of this BigDecimal without an exponent field.

public String toString ()

Returns the string representation of this BigDecimal, using scientific notation if an exponent is needed.

A standard canonical string form of the BigDecimal is created as though by the following steps: first, the absolute value of the unscaled value of the BigDecimal is converted to a string in base ten using the characters '0' through '9' with no leading zeros (except if its value is zero, in which case a single '0' character is used).

Next, an adjusted exponent is calculated; this is the negated scale, plus the number of characters in the converted unscaled value, less one. That is, -scale+(ulength-1), where ulength is the length of the absolute value of the unscaled value in decimal digits (its precision).

If the scale is greater than or equal to zero and the adjusted exponent is greater than or equal to -6, the number will be converted to a character form without using exponential notation. In this case, if the scale is zero then no decimal point is added and if the scale is positive a decimal point will be inserted with the scale specifying the number of characters to the right of the decimal point. '0' characters are added to the left of the converted unscaled value as necessary. If no character precedes the decimal point after this insertion then a conventional '0' character is prefixed.

Otherwise (that is, if the scale is negative, or the adjusted exponent is less than -6), the number will be converted to a character form using exponential notation. In this case, if the converted BigInteger has more than one digit a decimal point is inserted after the first digit. An exponent in character form is then suffixed to the converted unscaled value (perhaps with inserted decimal point); this comprises the letter 'E' followed immediately by the adjusted exponent converted to a character form. The latter is in base ten, using the characters '0' through '9' with no leading zeros, and is always prefixed by a sign character '-' ('\u002D') if the adjusted exponent is negative, '+' ('\u002B') otherwise).

Finally, the entire string is prefixed by a minus sign character '-' ('\u002D') if the unscaled value is less than zero. No sign character is prefixed if the unscaled value is zero or positive.

Examples:

For each representation [unscaled value, scale] on the left, the resulting string is shown on the right.

 [123,0]      "123"
 [-123,0]     "-123"
 [123,-1]     "1.23E+3"
 [123,-3]     "1.23E+5"
 [123,1]      "12.3"
 [123,5]      "0.00123"
 [123,10]     "1.23E-8"
 [-123,12]    "-1.23E-10"

Notes:

There is a one-to-one mapping between the distinguishable BigDecimal values and the result of this conversion. That is, every distinguishable BigDecimal value (unscaled value and scale) has a unique string representation as a result of using toString. If that string representation is converted back to a BigDecimal using the BigDecimal.BigDecimal(String) constructor, then the original value will be recovered.
The string produced for a given number is always the same; it is not affected by locale. This means that it can be used as a canonical string representation for exchanging decimal data, or as a key for a Hashtable, etc. Locale-sensitive number formatting and parsing is handled by the NumberFormat class and its subclasses.
The BigDecimal.toEngineeringString() method may be used for presenting numbers with exponents in engineering notation, and the setScale method may be used for rounding a BigDecimal so it has a known number of digits after the decimal point.
The digit-to-character mapping provided by Character.forDigit is used.

Returns: string representation of this BigDecimal.
See Also: Character.forDigit(int, int), BigDecimal.BigDecimal(java.lang.String),

public BigDecimal ulp ()

Returns the size of an ulp, a unit in the last place, of this BigDecimal.

Returns the size of an ulp, a unit in the last place, of this
BigDecimal. An ulp of a nonzero BigDecimal
value is the positive distance between this value and the
BigDecimal value next larger in magnitude with the
same number of digits. An ulp of a zero value is numerically
equal to 1 with the scale of this. The result is
stored with the same scale as this so the result
for zero and nonzero values is equal to

[1,
 this.scale()]

.
Returns: the size of an ulp of this
Since: 1.5

public BigInteger unscaledValue ()

Returns a BigInteger whose value is the unscaled value of this BigDecimal.

publicstatic BigDecimal valueOf (double val)

Translates a double into a BigDecimal, using the double's canonical string representation provided by the Double.toString(double) method.

publicstatic BigDecimal valueOf (long val)

Translates a long value into a BigDecimal with a scale of zero.

publicstatic BigDecimal valueOf (long unscaledVal, int scale)

Translates a long unscaled value and an int scale into a BigDecimal.