Fix incorrect seperator while concatenating shortcuts

We concatenate the selected shortcut with a comma
that is not localized. To fix it we use listformatter
to concatenate them.

Bug: 186891004
Test: manually test with differnt languages.
Change-Id: I2c6692facd457b434c56a0633e784ce771905b29

src/com/android/settings/utils/LocaleUtils.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed 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 com.android.settings.utils;
+
+import android.icu.text.ListFormatter;
+import android.text.TextUtils;
+
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * This class implements some common methods to process with locales
+ */
+public class LocaleUtils {
+
+    /**
+     * Returns a character sequence concatenating the items with the localized comma.
+     *
+     * @param items items to be concatenated
+     */
+    public static CharSequence getConcatenatedString(List<CharSequence> items) {
+        final ListFormatter listFormatter = ListFormatter.getInstance(Locale.getDefault());
+        final CharSequence lastItem =  items.get(items.size() - 1);
+        items.add("fake last item");
+
+        // For English with "{0}, {1}, and {2}", the pattern is "{0}, {1}, and {2}".
+        // To get "{0}, {1}, {2}", we add a {fake item}, then the pattern result would be
+        // "{0}, {1}, {2} and {fake item}", then get the substring with the end index of the
+        // last item.
+        final String formatted = listFormatter.format(items);
+        return formatted.subSequence(0, TextUtils.indexOf(formatted, lastItem) + lastItem.length());
+    }
+}