File	Doc	Category	Size	Date	Package
MathContext.java	API Doc	Java SE 5 API	11536	Fri Aug 26 14:57:06 BST 2005	java.math

MathContext

• java.lang.Object

Fields Summary
private static final int	DEFAULT_DIGITS
private static final RoundingMode	DEFAULT_ROUNDINGMODE
private static final int	MIN_DIGITS
private static final long	serialVersionUID
public static final MathContext	UNLIMITED A MathContext object whose settings have the values required for unlimited precision arithmetic. The values of the settings are: precision=0 roundingMode=HALF_UP
public static final MathContext	DECIMAL32 A MathContext object with a precision setting matching the IEEE 754R Decimal32 format, 7 digits, and a rounding mode of {@link RoundingMode#HALF_EVEN HALF_EVEN}, the IEEE 754R default.
public static final MathContext	DECIMAL64 A MathContext object with a precision setting matching the IEEE 754R Decimal64 format, 16 digits, and a rounding mode of {@link RoundingMode#HALF_EVEN HALF_EVEN}, the IEEE 754R default.
public static final MathContext	DECIMAL128 A MathContext object with a precision setting matching the IEEE 754R Decimal128 format, 34 digits, and a rounding mode of {@link RoundingMode#HALF_EVEN HALF_EVEN}, the IEEE 754R default.
final int	precision The number of digits to be used for an operation. A value of 0 indicates that unlimited precision (as many digits as are required) will be used. Note that leading zeros (in the coefficient of a number) are never significant. precision will always be non-negative.
final RoundingMode	roundingMode The rounding algorithm to be used for an operation.
transient BigInteger	roundingMax Lookaside for the rounding points (the numbers which determine whether the coefficient of a number will require rounding). These will be present if precision>0 and precision<=MAX_LOOKASIDE. In this case they will share the BigInteger int[] array. Note that the transients cannot be final because they are reconstructed on deserialization.
transient BigInteger	roundingMin
private static final int	MAX_LOOKASIDE

Constructors Summary
public MathContext(int setPrecision) Constructs a new MathContext with the specified precision and the {@link RoundingMode#HALF_UP HALF_UP} rounding mode. param setPrecision The non-negative int precision setting. throws IllegalArgumentException setPrecision parameter less than zero. /* ----- Constructors ----- */ this(setPrecision, DEFAULT_ROUNDINGMODE); return;
public MathContext(int setPrecision, RoundingMode setRoundingMode) Constructs a new MathContext with a specified precision and rounding mode. param setPrecision The non-negative int precision setting. param setRoundingMode The rounding mode to use. throws IllegalArgumentException setPrecision parameter less than zero. if (setPrecision < MIN_DIGITS) throw new IllegalArgumentException("Digits < 0"); if (setRoundingMode == null) throw new NullPointerException("null RoundingMode"); precision = setPrecision; if (precision > 0 && precision <= MAX_LOOKASIDE) { roundingMax = BigInteger.TEN.pow(precision); roundingMin = roundingMax.negate(); } roundingMode = setRoundingMode; return;
public MathContext(String val) Constructs a new MathContext from a string. The string must be in the same format as that produced by the {@link #toString} method. An IllegalArgumentException is thrown if the precision section of the string is out of range (< 0) or the string is not in the format created by the {@link #toString} method. param val The string to be parsed throws IllegalArgumentException precision parameter out of range or incorrect format boolean bad = false; int setPrecision; if (val == null) throw new NullPointerException("null String"); try { // any error here is a string format problem if (!val.startsWith("precision=")) throw new RuntimeException(); int fence = val.indexOf(' "); // could be -1 int off = 10; // where value starts setPrecision = Integer.parseInt(val.substring(10, fence)); if (!val.startsWith("roundingMode=", fence+1)) throw new RuntimeException(); off = fence + 1 + 13; String str = val.substring(off, val.length()); roundingMode = RoundingMode.valueOf(str); } catch (RuntimeException re) { throw new IllegalArgumentException("bad string format"); } if (setPrecision < MIN_DIGITS) throw new IllegalArgumentException("Digits < 0"); // the other parameters cannot be invalid if we got here precision = setPrecision; if (precision > 0 && precision <= MAX_LOOKASIDE) { roundingMax = BigInteger.TEN.pow(precision); roundingMin = roundingMax.negate(); }

Methods Summary
public boolean	equals(java.lang.Object x) Compares this MathContext with the specified Object for equality. param x Object to which this MathContext is to be compared. return true if and only if the specified Object is a MathContext object which has exactly the same settings as this object. MathContext mc; if (!(x instanceof MathContext)) return false; mc = (MathContext) x; return mc.precision == this.precision && mc.roundingMode == this.roundingMode; // no need for .equals()
public int	getPrecision() Returns the precision setting. This value is always non-negative. return an int which is the value of the precision setting return precision;
public java.math.RoundingMode	getRoundingMode() Returns the roundingMode setting. This will be one of {@link RoundingMode#CEILING}, {@link RoundingMode#DOWN}, {@link RoundingMode#FLOOR}, {@link RoundingMode#HALF_DOWN}, {@link RoundingMode#HALF_EVEN}, {@link RoundingMode#HALF_UP}, {@link RoundingMode#UNNECESSARY}, or {@link RoundingMode#UP}. return a RoundingMode object which is the value of the roundingMode setting return roundingMode;
public int	hashCode() Returns the hash code for this MathContext. return hash code for this MathContext return this.precision + roundingMode.hashCode() * 59;
private synchronized void	readObject(java.io.ObjectInputStream s) Reconstitute the MathContext instance from a stream (that is, deserialize it). param s the stream being read. s.defaultReadObject(); // read in all fields // validate possibly bad fields if (precision < MIN_DIGITS) { String message = "MathContext: invalid digits in stream"; throw new java.io.StreamCorruptedException(message); } if (roundingMode == null) { String message = "MathContext: null roundingMode in stream"; throw new java.io.StreamCorruptedException(message); } // Set the lookaside, if applicable if (precision <= MAX_LOOKASIDE) { roundingMax = BigInteger.TEN.pow(precision); roundingMin = roundingMax.negate(); }
public java.lang.String	toString() Returns the string representation of this MathContext. The String returned represents the settings of the MathContext object as two space-delimited words (separated by a single space character, '\u0020', and with no leading or trailing white space), as follows: The string "precision=", immediately followed by the value of the precision setting as a numeric string as if generated by the {@link Integer#toString(int) Integer.toString} method. The string "roundingMode=", immediately followed by the value of the roundingMode setting as a word. This word will be the same as the name of the corresponding public constant in the {@link RoundingMode} enum. For example: precision=9 roundingMode=HALF_UP Additional words may be appended to the result of toString in the future if more properties are added to this class. return a String representing the context settings. return "precision=" + precision + " " + "roundingMode=" + roundingMode.toString();