Use CharSequence for DisplayName

Change-Id: I2601eb9dc1edf585ad3b48da9fb97c65cb1face5

src/com/android/settings/DataUsageSummary.java

@@ -710,7 +710,7 @@ public class DataUsageSummary extends HighlightingFragment implements Indexable
     /**
      * Build {@link TabSpec} with thin indicator, and empty content.
      */
-    private TabSpec buildTabSpec(String tag, String title) {
+    private TabSpec buildTabSpec(String tag, CharSequence title) {
         return mTabHost.newTabSpec(tag).setIndicator(title).setContent(
                 mEmptyTabContent);
     }
@@ -2590,7 +2590,7 @@ public class DataUsageSummary extends HighlightingFragment implements Indexable
                 for (SubInfoRecord subInfo : mSubInfoList) {
                     if (hasReadyMobileRadio(context, subInfo.getSubscriptionId())) {
                         mTabHost.addTab(buildTabSpec(mMobileTagMap.get(subInfo.getSubscriptionId()),
-                                subInfo.getDisplayName().toString()));
+                                subInfo.getDisplayName()));
                     }
                 }
             }

src/com/android/settings/sim/SimSettings.java

@@ -370,7 +370,11 @@ public class SimSettings extends RestrictedSettingsFragment implements Indexable
         } else {
             for (int i = 0; i < selectableSubInfoLength; ++i) {
                 final SubInfoRecord sir = mSelectableSubInfos.get(i);
-                list.add(sir.getDisplayName().toString());
+                CharSequence displayName = sir.getDisplayName();
+                if (displayName == null) {
+                    displayName = "";
+                }
+                list.add(displayName.toString());
             }
         }