LocaleUtils.toLocale(String) cannot parse four segments

src/changes/changes.xml

@@ -49,6 +49,7 @@ The <action> type attribute can be add,update,fix,remove.
     <!-- FIX -->
     <action                   type="fix" dev="ggregory" due-to="Gary Gregory">Reimplement StopWatch internals to use java.time.</action>
     <action issue="LANG-1745" type="fix" dev="ggregory" due-to="Wang Hailong, Gary Gregory">RandomStringUtils.random() with a negative character index should throw IllegalArgumentException.</action>
+    <action issue="LANG-1741" type="fix" dev="ggregory" due-to="Wang Hailong, Gary Gregory">LocaleUtils.toLocale(String) cannot parse four segments.</action>
     <!-- ADD -->
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add StopWatch.getSplitDuration() and deprecate getSplitTime().</action>
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add StopWatch.getStartInstant() and deprecate getStartTime().</action>

src/main/java/org/apache/commons/lang3/LocaleUtils.java

@@ -249,28 +249,30 @@ public class LocaleUtils {
     }
 
     /**
-     * Tries to parse a locale from the given String.
+     * Tries to parse a Locale from the given String.
+     * <p>
+     * See {@Link Locale} for the format.
+     * </p>
      *
-     * @param str the String to parse a locale from.
+     * @param str the String to parse as a Locale.
-     * @return a Locale instance parsed from the given String.
+     * @return a Locale parsed from the given String.
      * @throws IllegalArgumentException if the given String can not be parsed.
+     * @see Locale
      */
     private static Locale parseLocale(final String str) {
         if (isISO639LanguageCode(str)) {
             return new Locale(str);
         }
-
+        final int limit = 3;
-        final String[] segments = str.indexOf(UNDERSCORE) != -1
+        final char separator = str.indexOf(UNDERSCORE) != -1 ? UNDERSCORE : DASH;
-            ? str.split(String.valueOf(UNDERSCORE), -1)
+        final String[] segments = str.split(String.valueOf(separator), 3);
-            : str.split(String.valueOf(DASH), -1);
         final String language = segments[0];
         if (segments.length == 2) {
             final String country = segments[1];
-            if (isISO639LanguageCode(language) && isISO3166CountryCode(country) ||
+            if (isISO639LanguageCode(language) && isISO3166CountryCode(country) || isNumericAreaCode(country)) {
-                    isNumericAreaCode(country)) {
                 return new Locale(language, country);
             }
-        } else if (segments.length == 3) {
+        } else if (segments.length == limit) {
             final String country = segments[1];
             final String variant = segments[2];
             if (isISO639LanguageCode(language) &&

src/test/java/org/apache/commons/lang3/LocaleUtilsTest.java

@@ -538,9 +538,10 @@ public class LocaleUtilsTest extends AbstractLangTest {
             assertValidToLocale("us_EN_a", "us", "EN", "A");
             assertValidToLocale("us_EN_SFsafdFDsdfF", "us", "EN", "SFSAFDFDSDFF");
         }
-
         assertThrows(IllegalArgumentException.class, () -> LocaleUtils.toLocale("us_EN-a"), "Should fail as no consistent delimiter");
         assertThrows(IllegalArgumentException.class, () -> LocaleUtils.toLocale("uu_UU_"), "Must be 3, 5 or 7+ in length");
+        // LANG-1741
+        assertEquals(new Locale("en", "001", "US_POSIX"), LocaleUtils.toLocale("en_001_US_POSIX"));
     }
 
     /**