Utility to compute a single subscription's unique display name.

Bug: 150370656
Bug: 148303118
Test: atest -c SubscriptionUtilTest
Change-Id: Id4600dbf038117129c62331f9e00b7035af1c0fd

src/com/android/settings/network/SubscriptionUtil.java

@@ -306,6 +306,24 @@ public class SubscriptionUtil {
                 info -> info.uniqueName));
     }
 
+    /**
+     * Return the display name for a subscription id, which is guaranteed to be unique.
+     * The logic to create this name has the following order of operations:
+     * 1) If the original display name is not unique, the last four digits of the phone number
+     *    will be appended.
+     * 2) If the phone number is not visible or the last four digits are shared with another
+     *    subscription, the subscription id will be appended to the original display name.
+     * More details can be found at go/unique-sub-display-names.
+     *
+     * @return map of active subscription ids to diaplay names.
+     */
+    @VisibleForTesting
+    public static CharSequence getUniqueSubscriptionDisplayName(
+            Integer subscriptionId, Context context) {
+        final Map<Integer, CharSequence> displayNames = getUniqueSubscriptionDisplayNames(context);
+        return displayNames.getOrDefault(subscriptionId, "");
+    }
+
     public static String getDisplayName(SubscriptionInfo info) {
         final CharSequence name = info.getDisplayName();
         if (name != null) {