--- a/jdk/src/java.base/share/classes/java/util/Locale.java	Fri Jun 17 04:35:09 2016 -0700
+++ b/jdk/src/java.base/share/classes/java/util/Locale.java	Fri Jun 17 21:42:38 2016 +0900
@@ -2888,7 +2888,7 @@
                 throw new IllegalArgumentException("weight=" + weight);
             }
 
-            range = range.toLowerCase();
+            range = range.toLowerCase(Locale.ROOT);
 
             // Do syntax check.
             boolean isIllFormed = false;

--- a/jdk/src/java.base/share/classes/sun/util/locale/LocaleMatcher.java	Fri Jun 17 04:35:09 2016 -0700
+++ b/jdk/src/java.base/share/classes/sun/util/locale/LocaleMatcher.java	Fri Jun 17 21:42:38 2016 +0900
@@ -118,7 +118,7 @@
                 return new ArrayList<String>(tags);
             } else {
                 for (String tag : tags) {
-                    tag = tag.toLowerCase();
+                    tag = tag.toLowerCase(Locale.ROOT);
                     if (tag.startsWith(range)) {
                         int len = range.length();
                         if ((tag.length() == len || tag.charAt(len) == '-')
@@ -143,7 +143,7 @@
             }
             String[] rangeSubtags = range.split("-");
             for (String tag : tags) {
-                tag = tag.toLowerCase();
+                tag = tag.toLowerCase(Locale.ROOT);
                 String[] tagSubtags = tag.split("-");
                 if (!rangeSubtags[0].equals(tagSubtags[0])
                     && !rangeSubtags[0].equals("*")) {
@@ -216,7 +216,7 @@
             String rangeForRegex = range.replaceAll("\\x2A", "\\\\p{Alnum}*");
             while (rangeForRegex.length() > 0) {
                 for (String tag : tags) {
-                    tag = tag.toLowerCase();
+                    tag = tag.toLowerCase(Locale.ROOT);
                     if (tag.matches(rangeForRegex)) {
                         return tag;
                     }
@@ -243,7 +243,7 @@
     }
 
     public static List<LanguageRange> parse(String ranges) {
-        ranges = ranges.replaceAll(" ", "").toLowerCase();
+        ranges = ranges.replaceAll(" ", "").toLowerCase(Locale.ROOT);
         if (ranges.startsWith("accept-language:")) {
             ranges = ranges.substring(16); // delete unnecessary prefix
         }
@@ -410,7 +410,7 @@
         // Create a map, key=originalKey.toLowerCaes(), value=originalKey
         Map<String, String> keyMap = new HashMap<>();
         for (String key : map.keySet()) {
-            keyMap.put(key.toLowerCase(), key);
+            keyMap.put(key.toLowerCase(Locale.ROOT), key);
         }
 
         List<LanguageRange> list = new ArrayList<>();
@@ -426,7 +426,7 @@
                     if (equivalents != null) {
                         int len = r.length();
                         for (String equivalent : equivalents) {
-                            list.add(new LanguageRange(equivalent.toLowerCase()
+                            list.add(new LanguageRange(equivalent.toLowerCase(Locale.ROOT)
                                      + range.substring(len),
                                      lr.getWeight()));
                         }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/util/Locale/Bug8159420.java	Fri Jun 17 21:42:38 2016 +0900
@@ -0,0 +1,224 @@
+/*
+ * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8159420
+ * @summary Checks the proper execution of LanguageRange.parse() and
+ *          other LocaleMatcher methods when used in the locales like
+ *          Turkish, because the toLowerCase() method is invoked in the
+ *          parse() and other LocaleMatcher methods.
+ *          e.g. "HI-Deva".toLowerCase() in the Turkish locale returns
+ *          "hı-deva", where 'ı' is the LATIN SMALL LETTER DOTLESS I character
+ *          which is not allowed in the language ranges/tags.
+ * @compile -encoding utf-8 Bug8159420.java
+ * @run main Bug8159420
+ */
+
+import java.util.List;
+import java.util.Locale;
+import java.util.Locale.LanguageRange;
+import java.util.Locale.FilteringMode;
+import java.util.LinkedHashMap;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.ArrayList;
+import static java.util.Locale.FilteringMode.EXTENDED_FILTERING;
+import static java.util.Locale.FilteringMode.AUTOSELECT_FILTERING;
+
+public class Bug8159420 {
+
+    static boolean err = false;
+
+    public static void main(String[] args) {
+
+        Locale origLocale = null;
+        try {
+
+            origLocale = Locale.getDefault();
+            Locale.setDefault(new Locale("tr", "TR"));
+            testParse();
+            testFilter(EXTENDED_FILTERING);
+            testFilter(AUTOSELECT_FILTERING);
+            testLookup();
+            testMapEquivalents();
+
+            if (err) {
+                throw new RuntimeException("[LocaleMatcher method(s) in turkish"
+                        + " locale failed]");
+            }
+
+        } finally {
+            Locale.setDefault(origLocale);
+        }
+
+    }
+
+    /* Before the fix, the testParse() method was throwing
+     * IllegalArgumentException in Turkish Locale
+     */
+    private static void testParse() {
+        String ranges = "HI-Deva, ja-hIrA-JP, RKI";
+        try {
+            LanguageRange.parse(ranges);
+        } catch (Exception ex) {
+            System.err.println("[testParse() failed on range string: "
+                    + ranges + "] due to "+ex);
+            err = true;
+        }
+    }
+
+    /* Before the fix, the testFilter() method was returning empty list in
+     * Turkish Locale
+     */
+    private static void testFilter(FilteringMode mode) {
+
+        String ranges = "hi-IN, itc-Ital";
+        String tags = "hi-IN, itc-Ital";
+        List<LanguageRange> priorityList = LanguageRange.parse(ranges);
+        List<Locale> tagList = generateLocales(tags);
+        String actualLocales = showLocales(Locale.filter(priorityList, tagList, mode));
+        String expectedLocales = "hi-IN, itc-Ital";
+
+        if (!expectedLocales.equals(actualLocales)) {
+            System.err.println("testFilter(" + mode + ") failed on language ranges:"
+                    + " [" + ranges + "] and language tags: [" + tags + "]");
+            err = true;
+        }
+    }
+
+    /* Before the fix, the testLookup() method was returning null in Turkish
+     * Locale
+     */
+    private static void testLookup() {
+        boolean error = false;
+        String ranges = "hi-IN, itc-Ital";
+        String tags = "hi-IN, itc-Ital";
+        List<LanguageRange> priorityList = LanguageRange.parse(ranges);
+        List<Locale> localeList = generateLocales(tags);
+        Locale actualLocale
+                = Locale.lookup(priorityList, localeList);
+        String actualLocaleString = "";
+
+        if (actualLocale != null) {
+            actualLocaleString = actualLocale.toLanguageTag();
+        } else {
+            error = true;
+        }
+
+        String expectedLocale = "hi-IN";
+
+        if (!expectedLocale.equals(actualLocaleString)) {
+            error = true;
+        }
+
+        if (error) {
+            System.err.println("testLookup() failed on language ranges:"
+                    + " [" + ranges + "] and language tags: [" + tags + "]");
+            err = true;
+        }
+
+    }
+
+    /* Before the fix, testMapEquivalents() method was returning only "hi-in"
+     * in Turkish Locale
+     */
+    private static void testMapEquivalents() {
+
+        String ranges = "HI-IN";
+        List<LanguageRange> priorityList = LanguageRange.parse(ranges);
+        HashMap<String, List<String>> map = new LinkedHashMap<>();
+        List<String> equivalentList = new ArrayList<>();
+        equivalentList.add("HI");
+        equivalentList.add("HI-Deva");
+        map.put("HI", equivalentList);
+
+        List<LanguageRange> expected = new ArrayList<>();
+        expected.add(new LanguageRange("hi-in"));
+        expected.add(new LanguageRange("hi-deva-in"));
+        List<LanguageRange> got
+                = LanguageRange.mapEquivalents(priorityList, map);
+
+        if (!areEqual(expected, got)) {
+            System.err.println("testMapEquivalents() failed");
+            err = true;
+        }
+
+    }
+
+    private static boolean areEqual(List<LanguageRange> expected,
+            List<LanguageRange> got) {
+
+        boolean error = false;
+        if (expected.equals(got)) {
+            return !error;
+        }
+
+        List<LanguageRange> cloneExpected = new ArrayList<>(expected);
+        cloneExpected.removeAll(got);
+        if (!cloneExpected.isEmpty()) {
+            error = true;
+            System.err.println("Found missing range(s): " + cloneExpected);
+        }
+
+        // not creating the 'got' clone as the list will not be used after this
+        got.removeAll(expected);
+        if (!got.isEmpty()) {
+            error = true;
+            System.err.println("Found extra range(s): " + got);
+        }
+        return !error;
+    }
+
+    private static List<Locale> generateLocales(String tags) {
+        if (tags == null) {
+            return null;
+        }
+
+        List<Locale> localeList = new ArrayList<>();
+        if (tags.equals("")) {
+            return localeList;
+        }
+        String[] t = tags.split(", ");
+        for (String tag : t) {
+            localeList.add(Locale.forLanguageTag(tag));
+        }
+        return localeList;
+    }
+
+    private static String showLocales(List<Locale> locales) {
+        StringBuilder sb = new StringBuilder();
+
+        Iterator<Locale> itr = locales.iterator();
+        if (itr.hasNext()) {
+            sb.append(itr.next().toLanguageTag());
+        }
+        while (itr.hasNext()) {
+            sb.append(", ");
+            sb.append(itr.next().toLanguageTag());
+        }
+
+        return sb.toString().trim();
+    }
+
+}