109 /**
110 * The number of digits to be used for an operation. A value of 0
111 * indicates that unlimited precision (as many digits as are
112 * required) will be used. Note that leading zeros (in the
113 * coefficient of a number) are never significant.
114 *
115 * <p>{@code precision} will always be non-negative.
116 *
117 * @serial
118 */
119 final int precision;
120
121 /**
122 * The rounding algorithm to be used for an operation.
123 *
124 * @see RoundingMode
125 * @serial
126 */
127 final RoundingMode roundingMode;
128
129 /**
130 * Lookaside for the rounding points (the numbers which determine
131 * whether the coefficient of a number will require rounding).
132 * These will be present if {@code precision > 0} and
133 * {@code precision <= MAX_LOOKASIDE}. In this case they will share the
134 * {@code BigInteger int[]} array. Note that the transients
135 * cannot be {@code final} because they are reconstructed on
136 * deserialization.
137 */
138 transient BigInteger roundingMax = null;
139 transient BigInteger roundingMin = null;
140 private static final int MAX_LOOKASIDE = 1000;
141
142 /* ----- Constructors ----- */
143
144 /**
145 * Constructs a new {@code MathContext} with the specified
146 * precision and the {@link RoundingMode#HALF_UP HALF_UP} rounding
147 * mode.
148 *
149 * @param setPrecision The non-negative {@code int} precision setting.
150 * @throws IllegalArgumentException if the {@code setPrecision} parameter is less
151 * than zero.
152 */
153 public MathContext(int setPrecision) {
154 this(setPrecision, DEFAULT_ROUNDINGMODE);
155 return;
156 }
157
158 /**
159 * Constructs a new {@code MathContext} with a specified
160 * precision and rounding mode.
161 *
162 * @param setPrecision The non-negative {@code int} precision setting.
163 * @param setRoundingMode The rounding mode to use.
164 * @throws IllegalArgumentException if the {@code setPrecision} parameter is less
165 * than zero.
166 * @throws NullPointerException if the rounding mode argument is {@code null}
167 */
168 public MathContext(int setPrecision,
169 RoundingMode setRoundingMode) {
170 if (setPrecision < MIN_DIGITS)
171 throw new IllegalArgumentException("Digits < 0");
172 if (setRoundingMode == null)
173 throw new NullPointerException("null RoundingMode");
174
175 precision = setPrecision;
176 if (precision > 0 && precision <= MAX_LOOKASIDE) {
177 roundingMax = BigInteger.TEN.pow(precision);
178 roundingMin = roundingMax.negate();
179 }
180
181 roundingMode = setRoundingMode;
182 return;
183 }
184
185 /**
186 * Constructs a new {@code MathContext} from a string.
187 *
188 * The string must be in the same format as that produced by the
189 * {@link #toString} method.
190 *
191 * <p>An {@code IllegalArgumentException} is thrown if the precision
192 * section of the string is out of range ({@code < 0}) or the string is
193 * not in the format created by the {@link #toString} method.
194 *
195 * @param val The string to be parsed
196 * @throws IllegalArgumentException if the precision section is out of range
197 * or of incorrect format
198 * @throws NullPointerException if the argument is {@code null}
199 */
200 public MathContext(String val) {
204 throw new NullPointerException("null String");
205 try { // any error here is a string format problem
206 if (!val.startsWith("precision=")) throw new RuntimeException();
207 int fence = val.indexOf(' '); // could be -1
208 int off = 10; // where value starts
209 setPrecision = Integer.parseInt(val.substring(10, fence));
210
211 if (!val.startsWith("roundingMode=", fence+1))
212 throw new RuntimeException();
213 off = fence + 1 + 13;
214 String str = val.substring(off, val.length());
215 roundingMode = RoundingMode.valueOf(str);
216 } catch (RuntimeException re) {
217 throw new IllegalArgumentException("bad string format");
218 }
219
220 if (setPrecision < MIN_DIGITS)
221 throw new IllegalArgumentException("Digits < 0");
222 // the other parameters cannot be invalid if we got here
223 precision = setPrecision;
224 if (precision > 0 && precision <= MAX_LOOKASIDE) {
225 roundingMax = BigInteger.TEN.pow(precision);
226 roundingMin = roundingMax.negate();
227 }
228 }
229
230 /**
231 * Returns the {@code precision} setting.
232 * This value is always non-negative.
233 *
234 * @return an {@code int} which is the value of the {@code precision}
235 * setting
236 */
237 public int getPrecision() {
238 return precision;
239 }
240
241 /**
242 * Returns the roundingMode setting.
243 * This will be one of
244 * {@link RoundingMode#CEILING},
245 * {@link RoundingMode#DOWN},
246 * {@link RoundingMode#FLOOR},
247 * {@link RoundingMode#HALF_DOWN},
248 * {@link RoundingMode#HALF_EVEN},
326 // Private methods
327
328 /**
329 * Reconstitute the {@code MathContext} instance from a stream (that is,
330 * deserialize it).
331 *
332 * @param s the stream being read.
333 */
334 private void readObject(java.io.ObjectInputStream s)
335 throws java.io.IOException, ClassNotFoundException {
336 s.defaultReadObject(); // read in all fields
337 // validate possibly bad fields
338 if (precision < MIN_DIGITS) {
339 String message = "MathContext: invalid digits in stream";
340 throw new java.io.StreamCorruptedException(message);
341 }
342 if (roundingMode == null) {
343 String message = "MathContext: null roundingMode in stream";
344 throw new java.io.StreamCorruptedException(message);
345 }
346 // Set the lookaside, if applicable
347 if (precision <= MAX_LOOKASIDE) {
348 roundingMax = BigInteger.TEN.pow(precision);
349 roundingMin = roundingMax.negate();
350 }
351 }
352
353 }
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109 /**
110 * The number of digits to be used for an operation. A value of 0
111 * indicates that unlimited precision (as many digits as are
112 * required) will be used. Note that leading zeros (in the
113 * coefficient of a number) are never significant.
114 *
115 * <p>{@code precision} will always be non-negative.
116 *
117 * @serial
118 */
119 final int precision;
120
121 /**
122 * The rounding algorithm to be used for an operation.
123 *
124 * @see RoundingMode
125 * @serial
126 */
127 final RoundingMode roundingMode;
128
129 /* ----- Constructors ----- */
130
131 /**
132 * Constructs a new {@code MathContext} with the specified
133 * precision and the {@link RoundingMode#HALF_UP HALF_UP} rounding
134 * mode.
135 *
136 * @param setPrecision The non-negative {@code int} precision setting.
137 * @throws IllegalArgumentException if the {@code setPrecision} parameter is less
138 * than zero.
139 */
140 public MathContext(int setPrecision) {
141 this(setPrecision, DEFAULT_ROUNDINGMODE);
142 return;
143 }
144
145 /**
146 * Constructs a new {@code MathContext} with a specified
147 * precision and rounding mode.
148 *
149 * @param setPrecision The non-negative {@code int} precision setting.
150 * @param setRoundingMode The rounding mode to use.
151 * @throws IllegalArgumentException if the {@code setPrecision} parameter is less
152 * than zero.
153 * @throws NullPointerException if the rounding mode argument is {@code null}
154 */
155 public MathContext(int setPrecision,
156 RoundingMode setRoundingMode) {
157 if (setPrecision < MIN_DIGITS)
158 throw new IllegalArgumentException("Digits < 0");
159 if (setRoundingMode == null)
160 throw new NullPointerException("null RoundingMode");
161
162 precision = setPrecision;
163 roundingMode = setRoundingMode;
164 return;
165 }
166
167 /**
168 * Constructs a new {@code MathContext} from a string.
169 *
170 * The string must be in the same format as that produced by the
171 * {@link #toString} method.
172 *
173 * <p>An {@code IllegalArgumentException} is thrown if the precision
174 * section of the string is out of range ({@code < 0}) or the string is
175 * not in the format created by the {@link #toString} method.
176 *
177 * @param val The string to be parsed
178 * @throws IllegalArgumentException if the precision section is out of range
179 * or of incorrect format
180 * @throws NullPointerException if the argument is {@code null}
181 */
182 public MathContext(String val) {
186 throw new NullPointerException("null String");
187 try { // any error here is a string format problem
188 if (!val.startsWith("precision=")) throw new RuntimeException();
189 int fence = val.indexOf(' '); // could be -1
190 int off = 10; // where value starts
191 setPrecision = Integer.parseInt(val.substring(10, fence));
192
193 if (!val.startsWith("roundingMode=", fence+1))
194 throw new RuntimeException();
195 off = fence + 1 + 13;
196 String str = val.substring(off, val.length());
197 roundingMode = RoundingMode.valueOf(str);
198 } catch (RuntimeException re) {
199 throw new IllegalArgumentException("bad string format");
200 }
201
202 if (setPrecision < MIN_DIGITS)
203 throw new IllegalArgumentException("Digits < 0");
204 // the other parameters cannot be invalid if we got here
205 precision = setPrecision;
206 }
207
208 /**
209 * Returns the {@code precision} setting.
210 * This value is always non-negative.
211 *
212 * @return an {@code int} which is the value of the {@code precision}
213 * setting
214 */
215 public int getPrecision() {
216 return precision;
217 }
218
219 /**
220 * Returns the roundingMode setting.
221 * This will be one of
222 * {@link RoundingMode#CEILING},
223 * {@link RoundingMode#DOWN},
224 * {@link RoundingMode#FLOOR},
225 * {@link RoundingMode#HALF_DOWN},
226 * {@link RoundingMode#HALF_EVEN},
304 // Private methods
305
306 /**
307 * Reconstitute the {@code MathContext} instance from a stream (that is,
308 * deserialize it).
309 *
310 * @param s the stream being read.
311 */
312 private void readObject(java.io.ObjectInputStream s)
313 throws java.io.IOException, ClassNotFoundException {
314 s.defaultReadObject(); // read in all fields
315 // validate possibly bad fields
316 if (precision < MIN_DIGITS) {
317 String message = "MathContext: invalid digits in stream";
318 throw new java.io.StreamCorruptedException(message);
319 }
320 if (roundingMode == null) {
321 String message = "MathContext: null roundingMode in stream";
322 throw new java.io.StreamCorruptedException(message);
323 }
324 }
325
326 }
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