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Statistical sampling library for use in virtdata libraries, based on apache commons math 4

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.lang3.time;

import java.text.DateFormat;
import java.text.Format;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Locale;
import java.util.TimeZone;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import org.apache.commons.lang3.Validate;

/**
 * 

FormatCache is a cache and factory for {@link Format}s.

* * @since 3.0 */ // TODO: Before making public move from getDateTimeInstance(Integer, ...) to int; or some other approach. abstract class FormatCache { /** * No date or no time. Used in same parameters as DateFormat.SHORT or DateFormat.LONG */ static final int NONE= -1; private final ConcurrentMap cInstanceCache = new ConcurrentHashMap<>(7); private static final ConcurrentMap cDateTimeInstanceCache = new ConcurrentHashMap<>(7); /** *

Gets a formatter instance using the default pattern in the * default timezone and locale.

* * @return a date/time formatter */ public F getInstance() { return getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT, TimeZone.getDefault(), Locale.getDefault()); } /** *

Gets a formatter instance using the specified pattern, time zone * and locale.

* * @param pattern {@link java.text.SimpleDateFormat} compatible * pattern, non-null * @param timeZone the time zone, null means use the default TimeZone * @param locale the locale, null means use the default Locale * @return a pattern based date/time formatter * @throws IllegalArgumentException if pattern is invalid * or null */ public F getInstance(final String pattern, TimeZone timeZone, Locale locale) { Validate.notNull(pattern, "pattern must not be null"); if (timeZone == null) { timeZone = TimeZone.getDefault(); } if (locale == null) { locale = Locale.getDefault(); } final MultipartKey key = new MultipartKey(pattern, timeZone, locale); F format = cInstanceCache.get(key); if (format == null) { format = createInstance(pattern, timeZone, locale); final F previousValue= cInstanceCache.putIfAbsent(key, format); if (previousValue != null) { // another thread snuck in and did the same work // we should return the instance that is in ConcurrentMap format= previousValue; } } return format; } /** *

Create a format instance using the specified pattern, time zone * and locale.

* * @param pattern {@link java.text.SimpleDateFormat} compatible pattern, this will not be null. * @param timeZone time zone, this will not be null. * @param locale locale, this will not be null. * @return a pattern based date/time formatter * @throws IllegalArgumentException if pattern is invalid * or null */ protected abstract F createInstance(String pattern, TimeZone timeZone, Locale locale); /** *

Gets a date/time formatter instance using the specified style, * time zone and locale.

* * @param dateStyle date style: FULL, LONG, MEDIUM, or SHORT, null indicates no date in format * @param timeStyle time style: FULL, LONG, MEDIUM, or SHORT, null indicates no time in format * @param timeZone optional time zone, overrides time zone of * formatted date, null means use default Locale * @param locale optional locale, overrides system locale * @return a localized standard date/time formatter * @throws IllegalArgumentException if the Locale has no date/time * pattern defined */ // This must remain private, see LANG-884 private F getDateTimeInstance(final Integer dateStyle, final Integer timeStyle, final TimeZone timeZone, Locale locale) { if (locale == null) { locale = Locale.getDefault(); } final String pattern = getPatternForStyle(dateStyle, timeStyle, locale); return getInstance(pattern, timeZone, locale); } /** *

Gets a date/time formatter instance using the specified style, * time zone and locale.

* * @param dateStyle date style: FULL, LONG, MEDIUM, or SHORT * @param timeStyle time style: FULL, LONG, MEDIUM, or SHORT * @param timeZone optional time zone, overrides time zone of * formatted date, null means use default Locale * @param locale optional locale, overrides system locale * @return a localized standard date/time formatter * @throws IllegalArgumentException if the Locale has no date/time * pattern defined */ // package protected, for access from FastDateFormat; do not make public or protected F getDateTimeInstance(final int dateStyle, final int timeStyle, final TimeZone timeZone, final Locale locale) { return getDateTimeInstance(Integer.valueOf(dateStyle), Integer.valueOf(timeStyle), timeZone, locale); } /** *

Gets a date formatter instance using the specified style, * time zone and locale.

* * @param dateStyle date style: FULL, LONG, MEDIUM, or SHORT * @param timeZone optional time zone, overrides time zone of * formatted date, null means use default Locale * @param locale optional locale, overrides system locale * @return a localized standard date/time formatter * @throws IllegalArgumentException if the Locale has no date/time * pattern defined */ // package protected, for access from FastDateFormat; do not make public or protected F getDateInstance(final int dateStyle, final TimeZone timeZone, final Locale locale) { return getDateTimeInstance(Integer.valueOf(dateStyle), null, timeZone, locale); } /** *

Gets a time formatter instance using the specified style, * time zone and locale.

* * @param timeStyle time style: FULL, LONG, MEDIUM, or SHORT * @param timeZone optional time zone, overrides time zone of * formatted date, null means use default Locale * @param locale optional locale, overrides system locale * @return a localized standard date/time formatter * @throws IllegalArgumentException if the Locale has no date/time * pattern defined */ // package protected, for access from FastDateFormat; do not make public or protected F getTimeInstance(final int timeStyle, final TimeZone timeZone, final Locale locale) { return getDateTimeInstance(null, Integer.valueOf(timeStyle), timeZone, locale); } /** *

Gets a date/time format for the specified styles and locale.

* * @param dateStyle date style: FULL, LONG, MEDIUM, or SHORT, null indicates no date in format * @param timeStyle time style: FULL, LONG, MEDIUM, or SHORT, null indicates no time in format * @param locale The non-null locale of the desired format * @return a localized standard date/time format * @throws IllegalArgumentException if the Locale has no date/time pattern defined */ // package protected, for access from test code; do not make public or protected static String getPatternForStyle(final Integer dateStyle, final Integer timeStyle, final Locale locale) { final MultipartKey key = new MultipartKey(dateStyle, timeStyle, locale); String pattern = cDateTimeInstanceCache.get(key); if (pattern == null) { try { DateFormat formatter; if (dateStyle == null) { formatter = DateFormat.getTimeInstance(timeStyle.intValue(), locale); } else if (timeStyle == null) { formatter = DateFormat.getDateInstance(dateStyle.intValue(), locale); } else { formatter = DateFormat.getDateTimeInstance(dateStyle.intValue(), timeStyle.intValue(), locale); } pattern = ((SimpleDateFormat) formatter).toPattern(); final String previous = cDateTimeInstanceCache.putIfAbsent(key, pattern); if (previous != null) { // even though it doesn't matter if another thread put the pattern // it's still good practice to return the String instance that is // actually in the ConcurrentMap pattern= previous; } } catch (final ClassCastException ex) { throw new IllegalArgumentException("No date time pattern for locale: " + locale); } } return pattern; } // ---------------------------------------------------------------------- /** *

Helper class to hold multi-part Map keys

*/ private static class MultipartKey { private final Object[] keys; private int hashCode; /** * Constructs an instance of MultipartKey to hold the specified objects. * @param keys the set of objects that make up the key. Each key may be null. */ MultipartKey(final Object... keys) { this.keys = keys; } /** * {@inheritDoc} */ @Override public boolean equals(final Object obj) { // Eliminate the usual boilerplate because // this inner static class is only used in a generic ConcurrentHashMap // which will not compare against other Object types return Arrays.equals(keys, ((MultipartKey) obj).keys); } /** * {@inheritDoc} */ @Override public int hashCode() { if (hashCode==0) { int rc= 0; for (final Object key : keys) { if (key!=null) { rc= rc*7 + key.hashCode(); } } hashCode= rc; } return hashCode; } } }




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