History

My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

Showing the changes to java/pkg/java/math/RoundingMode.java (1 of 18352 files). Show all

Unified · Split

java/pkg/java/math/RoundingMode.java+349−0
@@ -0,0 +1,349 @@
1+/*
2+ * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
3+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4+ *
5+ * This code is free software; you can redistribute it and/or modify it
6+ * under the terms of the GNU General Public License version 2 only, as
7+ * published by the Free Software Foundation. Oracle designates this
8+ * particular file as subject to the "Classpath" exception as provided
9+ * by Oracle in the LICENSE file that accompanied this code.
10+ *
11+ * This code is distributed in the hope that it will be useful, but WITHOUT
12+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14+ * version 2 for more details (a copy is included in the LICENSE file that
15+ * accompanied this code).
16+ *
17+ * You should have received a copy of the GNU General Public License version
18+ * 2 along with this work; if not, write to the Free Software Foundation,
19+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20+ *
21+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22+ * or visit www.oracle.com if you need additional information or have any
23+ * questions.
24+ */
25+
26+/*
27+ * Portions Copyright IBM Corporation, 2001. All Rights Reserved.
28+ */
29+package java.math;
30+
31+/**
32+ * Specifies a <i>rounding behavior</i> for numerical operations
33+ * capable of discarding precision. Each rounding mode indicates how
34+ * the least significant returned digit of a rounded result is to be
35+ * calculated. If fewer digits are returned than the digits needed to
36+ * represent the exact numerical result, the discarded digits will be
37+ * referred to as the <i>discarded fraction</i> regardless the digits'
38+ * contribution to the value of the number. In other words,
39+ * considered as a numerical value, the discarded fraction could have
40+ * an absolute value greater than one.
41+ *
42+ * <p>Each rounding mode description includes a table listing how
43+ * different two-digit decimal values would round to a one digit
44+ * decimal value under the rounding mode in question. The result
45+ * column in the tables could be gotten by creating a
46+ * {@code BigDecimal} number with the specified value, forming a
47+ * {@link MathContext} object with the proper settings
48+ * ({@code precision} set to {@code 1}, and the
49+ * {@code roundingMode} set to the rounding mode in question), and
50+ * calling {@link BigDecimal#round round} on this number with the
51+ * proper {@code MathContext}. A summary table showing the results
52+ * of these rounding operations for all rounding modes appears below.
53+ *
54+ *<p>
55+ *<table border>
56+ * <caption><b>Summary of Rounding Operations Under Different Rounding Modes</b></caption>
57+ * <tr><th></th><th colspan=8>Result of rounding input to one digit with the given
58+ * rounding mode</th>
59+ * <tr valign=top>
60+ * <th>Input Number</th> <th>{@code UP}</th>
61+ * <th>{@code DOWN}</th>
62+ * <th>{@code CEILING}</th>
63+ * <th>{@code FLOOR}</th>
64+ * <th>{@code HALF_UP}</th>
65+ * <th>{@code HALF_DOWN}</th>
66+ * <th>{@code HALF_EVEN}</th>
67+ * <th>{@code UNNECESSARY}</th>
68+ *
69+ * <tr align=right><td>5.5</td> <td>6</td> <td>5</td> <td>6</td> <td>5</td> <td>6</td> <td>5</td> <td>6</td> <td>throw {@code ArithmeticException}</td>
70+ * <tr align=right><td>2.5</td> <td>3</td> <td>2</td> <td>3</td> <td>2</td> <td>3</td> <td>2</td> <td>2</td> <td>throw {@code ArithmeticException}</td>
71+ * <tr align=right><td>1.6</td> <td>2</td> <td>1</td> <td>2</td> <td>1</td> <td>2</td> <td>2</td> <td>2</td> <td>throw {@code ArithmeticException}</td>
72+ * <tr align=right><td>1.1</td> <td>2</td> <td>1</td> <td>2</td> <td>1</td> <td>1</td> <td>1</td> <td>1</td> <td>throw {@code ArithmeticException}</td>
73+ * <tr align=right><td>1.0</td> <td>1</td> <td>1</td> <td>1</td> <td>1</td> <td>1</td> <td>1</td> <td>1</td> <td>1</td>
74+ * <tr align=right><td>-1.0</td> <td>-1</td> <td>-1</td> <td>-1</td> <td>-1</td> <td>-1</td> <td>-1</td> <td>-1</td> <td>-1</td>
75+ * <tr align=right><td>-1.1</td> <td>-2</td> <td>-1</td> <td>-1</td> <td>-2</td> <td>-1</td> <td>-1</td> <td>-1</td> <td>throw {@code ArithmeticException}</td>
76+ * <tr align=right><td>-1.6</td> <td>-2</td> <td>-1</td> <td>-1</td> <td>-2</td> <td>-2</td> <td>-2</td> <td>-2</td> <td>throw {@code ArithmeticException}</td>
77+ * <tr align=right><td>-2.5</td> <td>-3</td> <td>-2</td> <td>-2</td> <td>-3</td> <td>-3</td> <td>-2</td> <td>-2</td> <td>throw {@code ArithmeticException}</td>
78+ * <tr align=right><td>-5.5</td> <td>-6</td> <td>-5</td> <td>-5</td> <td>-6</td> <td>-6</td> <td>-5</td> <td>-6</td> <td>throw {@code ArithmeticException}</td>
79+ *</table>
80+ *
81+ *
82+ * <p>This {@code enum} is intended to replace the integer-based
83+ * enumeration of rounding mode constants in {@link BigDecimal}
84+ * ({@link BigDecimal#ROUND_UP}, {@link BigDecimal#ROUND_DOWN},
85+ * etc. ).
86+ *
87+ * @see BigDecimal
88+ * @see MathContext
89+ * @author Josh Bloch
90+ * @author Mike Cowlishaw
91+ * @author Joseph D. Darcy
92+ * @since 1.5
93+ */
94+public enum RoundingMode {
95+
96+ /**
97+ * Rounding mode to round away from zero. Always increments the
98+ * digit prior to a non-zero discarded fraction. Note that this
99+ * rounding mode never decreases the magnitude of the calculated
100+ * value.
101+ *
102+ *<p>Example:
103+ *<table border>
104+ *<tr valign=top><th>Input Number</th>
105+ * <th>Input rounded to one digit<br> with {@code UP} rounding
106+ *<tr align=right><td>5.5</td> <td>6</td>
107+ *<tr align=right><td>2.5</td> <td>3</td>
108+ *<tr align=right><td>1.6</td> <td>2</td>
109+ *<tr align=right><td>1.1</td> <td>2</td>
110+ *<tr align=right><td>1.0</td> <td>1</td>
111+ *<tr align=right><td>-1.0</td> <td>-1</td>
112+ *<tr align=right><td>-1.1</td> <td>-2</td>
113+ *<tr align=right><td>-1.6</td> <td>-2</td>
114+ *<tr align=right><td>-2.5</td> <td>-3</td>
115+ *<tr align=right><td>-5.5</td> <td>-6</td>
116+ *</table>
117+ */
118+ UP(BigDecimal.ROUND_UP),
119+
120+ /**
121+ * Rounding mode to round towards zero. Never increments the digit
122+ * prior to a discarded fraction (i.e., truncates). Note that this
123+ * rounding mode never increases the magnitude of the calculated value.
124+ *
125+ *<p>Example:
126+ *<table border>
127+ *<tr valign=top><th>Input Number</th>
128+ * <th>Input rounded to one digit<br> with {@code DOWN} rounding
129+ *<tr align=right><td>5.5</td> <td>5</td>
130+ *<tr align=right><td>2.5</td> <td>2</td>
131+ *<tr align=right><td>1.6</td> <td>1</td>
132+ *<tr align=right><td>1.1</td> <td>1</td>
133+ *<tr align=right><td>1.0</td> <td>1</td>
134+ *<tr align=right><td>-1.0</td> <td>-1</td>
135+ *<tr align=right><td>-1.1</td> <td>-1</td>
136+ *<tr align=right><td>-1.6</td> <td>-1</td>
137+ *<tr align=right><td>-2.5</td> <td>-2</td>
138+ *<tr align=right><td>-5.5</td> <td>-5</td>
139+ *</table>
140+ */
141+ DOWN(BigDecimal.ROUND_DOWN),
142+
143+ /**
144+ * Rounding mode to round towards positive infinity. If the
145+ * result is positive, behaves as for {@code RoundingMode.UP};
146+ * if negative, behaves as for {@code RoundingMode.DOWN}. Note
147+ * that this rounding mode never decreases the calculated value.
148+ *
149+ *<p>Example:
150+ *<table border>
151+ *<tr valign=top><th>Input Number</th>
152+ * <th>Input rounded to one digit<br> with {@code CEILING} rounding
153+ *<tr align=right><td>5.5</td> <td>6</td>
154+ *<tr align=right><td>2.5</td> <td>3</td>
155+ *<tr align=right><td>1.6</td> <td>2</td>
156+ *<tr align=right><td>1.1</td> <td>2</td>
157+ *<tr align=right><td>1.0</td> <td>1</td>
158+ *<tr align=right><td>-1.0</td> <td>-1</td>
159+ *<tr align=right><td>-1.1</td> <td>-1</td>
160+ *<tr align=right><td>-1.6</td> <td>-1</td>
161+ *<tr align=right><td>-2.5</td> <td>-2</td>
162+ *<tr align=right><td>-5.5</td> <td>-5</td>
163+ *</table>
164+ */
165+ CEILING(BigDecimal.ROUND_CEILING),
166+
167+ /**
168+ * Rounding mode to round towards negative infinity. If the
169+ * result is positive, behave as for {@code RoundingMode.DOWN};
170+ * if negative, behave as for {@code RoundingMode.UP}. Note that
171+ * this rounding mode never increases the calculated value.
172+ *
173+ *<p>Example:
174+ *<table border>
175+ *<tr valign=top><th>Input Number</th>
176+ * <th>Input rounded to one digit<br> with {@code FLOOR} rounding
177+ *<tr align=right><td>5.5</td> <td>5</td>
178+ *<tr align=right><td>2.5</td> <td>2</td>
179+ *<tr align=right><td>1.6</td> <td>1</td>
180+ *<tr align=right><td>1.1</td> <td>1</td>
181+ *<tr align=right><td>1.0</td> <td>1</td>
182+ *<tr align=right><td>-1.0</td> <td>-1</td>
183+ *<tr align=right><td>-1.1</td> <td>-2</td>
184+ *<tr align=right><td>-1.6</td> <td>-2</td>
185+ *<tr align=right><td>-2.5</td> <td>-3</td>
186+ *<tr align=right><td>-5.5</td> <td>-6</td>
187+ *</table>
188+ */
189+ FLOOR(BigDecimal.ROUND_FLOOR),
190+
191+ /**
192+ * Rounding mode to round towards {@literal "nearest neighbor"}
193+ * unless both neighbors are equidistant, in which case round up.
194+ * Behaves as for {@code RoundingMode.UP} if the discarded
195+ * fraction is &ge; 0.5; otherwise, behaves as for
196+ * {@code RoundingMode.DOWN}. Note that this is the rounding
197+ * mode commonly taught at school.
198+ *
199+ *<p>Example:
200+ *<table border>
201+ *<tr valign=top><th>Input Number</th>
202+ * <th>Input rounded to one digit<br> with {@code HALF_UP} rounding
203+ *<tr align=right><td>5.5</td> <td>6</td>
204+ *<tr align=right><td>2.5</td> <td>3</td>
205+ *<tr align=right><td>1.6</td> <td>2</td>
206+ *<tr align=right><td>1.1</td> <td>1</td>
207+ *<tr align=right><td>1.0</td> <td>1</td>
208+ *<tr align=right><td>-1.0</td> <td>-1</td>
209+ *<tr align=right><td>-1.1</td> <td>-1</td>
210+ *<tr align=right><td>-1.6</td> <td>-2</td>
211+ *<tr align=right><td>-2.5</td> <td>-3</td>
212+ *<tr align=right><td>-5.5</td> <td>-6</td>
213+ *</table>
214+ */
215+ HALF_UP(BigDecimal.ROUND_HALF_UP),
216+
217+ /**
218+ * Rounding mode to round towards {@literal "nearest neighbor"}
219+ * unless both neighbors are equidistant, in which case round
220+ * down. Behaves as for {@code RoundingMode.UP} if the discarded
221+ * fraction is &gt; 0.5; otherwise, behaves as for
222+ * {@code RoundingMode.DOWN}.
223+ *
224+ *<p>Example:
225+ *<table border>
226+ *<tr valign=top><th>Input Number</th>
227+ * <th>Input rounded to one digit<br> with {@code HALF_DOWN} rounding
228+ *<tr align=right><td>5.5</td> <td>5</td>
229+ *<tr align=right><td>2.5</td> <td>2</td>
230+ *<tr align=right><td>1.6</td> <td>2</td>
231+ *<tr align=right><td>1.1</td> <td>1</td>
232+ *<tr align=right><td>1.0</td> <td>1</td>
233+ *<tr align=right><td>-1.0</td> <td>-1</td>
234+ *<tr align=right><td>-1.1</td> <td>-1</td>
235+ *<tr align=right><td>-1.6</td> <td>-2</td>
236+ *<tr align=right><td>-2.5</td> <td>-2</td>
237+ *<tr align=right><td>-5.5</td> <td>-5</td>
238+ *</table>
239+ */
240+ HALF_DOWN(BigDecimal.ROUND_HALF_DOWN),
241+
242+ /**
243+ * Rounding mode to round towards the {@literal "nearest neighbor"}
244+ * unless both neighbors are equidistant, in which case, round
245+ * towards the even neighbor. Behaves as for
246+ * {@code RoundingMode.HALF_UP} if the digit to the left of the
247+ * discarded fraction is odd; behaves as for
248+ * {@code RoundingMode.HALF_DOWN} if it's even. Note that this
249+ * is the rounding mode that statistically minimizes cumulative
250+ * error when applied repeatedly over a sequence of calculations.
251+ * It is sometimes known as {@literal "Banker's rounding,"} and is
252+ * chiefly used in the USA. This rounding mode is analogous to
253+ * the rounding policy used for {@code float} and {@code double}
254+ * arithmetic in Java.
255+ *
256+ *<p>Example:
257+ *<table border>
258+ *<tr valign=top><th>Input Number</th>
259+ * <th>Input rounded to one digit<br> with {@code HALF_EVEN} rounding
260+ *<tr align=right><td>5.5</td> <td>6</td>
261+ *<tr align=right><td>2.5</td> <td>2</td>
262+ *<tr align=right><td>1.6</td> <td>2</td>
263+ *<tr align=right><td>1.1</td> <td>1</td>
264+ *<tr align=right><td>1.0</td> <td>1</td>
265+ *<tr align=right><td>-1.0</td> <td>-1</td>
266+ *<tr align=right><td>-1.1</td> <td>-1</td>
267+ *<tr align=right><td>-1.6</td> <td>-2</td>
268+ *<tr align=right><td>-2.5</td> <td>-2</td>
269+ *<tr align=right><td>-5.5</td> <td>-6</td>
270+ *</table>
271+ */
272+ HALF_EVEN(BigDecimal.ROUND_HALF_EVEN),
273+
274+ /**
275+ * Rounding mode to assert that the requested operation has an exact
276+ * result, hence no rounding is necessary. If this rounding mode is
277+ * specified on an operation that yields an inexact result, an
278+ * {@code ArithmeticException} is thrown.
279+ *<p>Example:
280+ *<table border>
281+ *<tr valign=top><th>Input Number</th>
282+ * <th>Input rounded to one digit<br> with {@code UNNECESSARY} rounding
283+ *<tr align=right><td>5.5</td> <td>throw {@code ArithmeticException}</td>
284+ *<tr align=right><td>2.5</td> <td>throw {@code ArithmeticException}</td>
285+ *<tr align=right><td>1.6</td> <td>throw {@code ArithmeticException}</td>
286+ *<tr align=right><td>1.1</td> <td>throw {@code ArithmeticException}</td>
287+ *<tr align=right><td>1.0</td> <td>1</td>
288+ *<tr align=right><td>-1.0</td> <td>-1</td>
289+ *<tr align=right><td>-1.1</td> <td>throw {@code ArithmeticException}</td>
290+ *<tr align=right><td>-1.6</td> <td>throw {@code ArithmeticException}</td>
291+ *<tr align=right><td>-2.5</td> <td>throw {@code ArithmeticException}</td>
292+ *<tr align=right><td>-5.5</td> <td>throw {@code ArithmeticException}</td>
293+ *</table>
294+ */
295+ UNNECESSARY(BigDecimal.ROUND_UNNECESSARY);
296+
297+ // Corresponding BigDecimal rounding constant
298+ final int oldMode;
299+
300+ /**
301+ * Constructor
302+ *
303+ * @param oldMode The {@code BigDecimal} constant corresponding to
304+ * this mode
305+ */
306+ private RoundingMode(int oldMode) {
307+ this.oldMode = oldMode;
308+ }
309+
310+ /**
311+ * Returns the {@code RoundingMode} object corresponding to a
312+ * legacy integer rounding mode constant in {@link BigDecimal}.
313+ *
314+ * @param rm legacy integer rounding mode to convert
315+ * @return {@code RoundingMode} corresponding to the given integer.
316+ * @throws IllegalArgumentException integer is out of range
317+ */
318+ public static RoundingMode valueOf(int rm) {
319+ switch(rm) {
320+
321+ case BigDecimal.ROUND_UP:
322+ return UP;
323+
324+ case BigDecimal.ROUND_DOWN:
325+ return DOWN;
326+
327+ case BigDecimal.ROUND_CEILING:
328+ return CEILING;
329+
330+ case BigDecimal.ROUND_FLOOR:
331+ return FLOOR;
332+
333+ case BigDecimal.ROUND_HALF_UP:
334+ return HALF_UP;
335+
336+ case BigDecimal.ROUND_HALF_DOWN:
337+ return HALF_DOWN;
338+
339+ case BigDecimal.ROUND_HALF_EVEN:
340+ return HALF_EVEN;
341+
342+ case BigDecimal.ROUND_UNNECESSARY:
343+ return UNNECESSARY;
344+
345+ default:
346+ throw new IllegalArgumentException("argument out of range");
347+ }
348+ }
349+}