Fix getLocalInstanceCount crashing when Realms are closed again. (#3798)

Author: cmelchior

CHANGELOG.md

@@ -7,6 +7,7 @@
 ### Bug fixes
 
 * Added version number to the native library, preventing ReLinker from accidentally loading old code (#3775).
+* `Realm.getLocalInstanceCount(config)` throwing NullPointerException if called after all Realms have been closed (#3791).
 
 ## 2.2.0
 

realm/realm-library/src/androidTest/java/io/realm/RealmTests.java

@@ -3796,20 +3796,20 @@ public void run() {
     @Test
     public void getLocalInstanceCount() {
         final RealmConfiguration config = configFactory.createConfiguration("localInstanceCount");
-        assertEquals(0, Realm.getGlobalInstanceCount(config));
+        assertEquals(0, Realm.getLocalInstanceCount(config));
 
         // Open thread local Realm
         Realm realm = Realm.getInstance(config);
-        assertEquals(1, Realm.getGlobalInstanceCount(config));
+        assertEquals(1, Realm.getLocalInstanceCount(config));
 
         // Open thread local DynamicRealm
         DynamicRealm dynRealm = DynamicRealm.getInstance(config);
-        assertEquals(2, Realm.getGlobalInstanceCount(config));
+        assertEquals(2, Realm.getLocalInstanceCount(config));
 
         dynRealm.close();
-        assertEquals(1, Realm.getGlobalInstanceCount(config));
+        assertEquals(1, Realm.getLocalInstanceCount(config));
         realm.close();
-        assertEquals(0, Realm.getGlobalInstanceCount(config));
+        assertEquals(0, Realm.getLocalInstanceCount(config));
     }
 
     @Test

realm/realm-library/src/main/java/io/realm/RealmCache.java

@@ -402,7 +402,8 @@ static int getLocalThreadCount(RealmConfiguration configuration) {
         } else {
             int totalRefCount = 0;
             for (RealmCacheType type : RealmCacheType.values()) {
-                totalRefCount += cache.refAndCountMap.get(type).localCount.get();
+                Integer localCount = cache.refAndCountMap.get(type).localCount.get();
+                totalRefCount += (localCount != null) ? localCount : 0;
             }
             return totalRefCount;
         }