Sort the available TimeZone IDs once.

Author: garydgregory

src/main/java/org/apache/commons/lang3/time/FastDateParser.java

@@ -44,7 +44,6 @@
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
-import org.apache.commons.lang3.ArraySorter;
 import org.apache.commons.lang3.CharUtils;
 import org.apache.commons.lang3.LocaleUtils;
 import org.apache.commons.lang3.StringUtils;
@@ -581,7 +580,7 @@ static boolean skipTimeZone(final String tzId) {
                 }
             }
             // Order is undefined.
-            for (final String tzId : ArraySorter.sort(TimeZone.getAvailableIDs())) {
+            for (final String tzId : TimeZones.SORTED_AVAILABLE_IDS) {
                 if (skipTimeZone(tzId)) {
                     continue;
                 }

src/main/java/org/apache/commons/lang3/time/TimeZones.java

@@ -20,6 +20,7 @@
 import java.time.ZoneId;
 import java.util.TimeZone;
 
+import org.apache.commons.lang3.ArraySorter;
 import org.apache.commons.lang3.JavaVersion;
 import org.apache.commons.lang3.ObjectUtils;
 import org.apache.commons.lang3.SystemProperties;
@@ -82,6 +83,15 @@ public static TimeZone toTimeZone(final TimeZone timeZone) {
         return ObjectUtils.getIfNull(timeZone, TimeZone::getDefault);
     }
 
+    /**
+     * The sorted available IDs.
+     * <p>
+     * Make a defensive copy, just in case.
+     * </p>
+     * @see TimeZone#getAvailableIDs()
+     */
+    static final String[] SORTED_AVAILABLE_IDS = ArraySorter.sort(TimeZone.getAvailableIDs().clone());
+
     /** Do not instantiate. */
     private TimeZones() {
     }

src/test/java/org/apache/commons/lang3/time/FastDateParser_TimeZoneStrategyTest.java

@@ -216,7 +216,7 @@ private void testTimeZoneStrategyPattern_TimeZone_getAvailableIDs(final Locale l
         Objects.requireNonNull(locale, "locale");
         assumeFalse(LocaleUtils.isLanguageUndetermined(locale), () -> toFailureMessage(locale, null, null));
         assumeTrue(LocaleUtils.isAvailableLocale(locale), () -> toFailureMessage(locale, null, null));
-        for (final String id : ArraySorter.sort(TimeZone.getAvailableIDs())) {
+        for (final String id : TimeZones.SORTED_AVAILABLE_IDS) {
             final TimeZone timeZone = TimeZones.getTimeZone(id);
             final String displayName = timeZone.getDisplayName(locale);
             final FastDateParser parser = new FastDateParser("z", timeZone, locale);

src/test/java/org/apache/commons/lang3/time/FastDatePrinterTimeZonesTest.java

@@ -32,7 +32,7 @@ class FastDatePrinterTimeZonesTest extends AbstractLangTest {
     private static final String PATTERN = "h:mma z";
 
     public static Stream<TimeZone> data() {
-        return Stream.of(TimeZone.getAvailableIDs()).map(TimeZones::getTimeZone);
+        return Stream.of(TimeZones.SORTED_AVAILABLE_IDS).map(TimeZones::getTimeZone);
     }
 
     @ParameterizedTest