Refactor preference upgrade

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/Preferences.java

@@ -433,11 +433,33 @@ public class Preferences {
 
             switch (oldVersion) {
                 case 1:
-                    // fall through
                 case 2:
-                    // fall through
                 case 3: {
-                    // migrate keyserver to hkps
+                    migrateToHkps();
+                }
+                case 4: {
+                    setTheme(Constants.Pref.Theme.DEFAULT);
+                }
+                case 5: {
+                    KeyserverSyncAdapterService.enableKeyserverSync(context);
+                }
+                case 6:
+                case 7: {
+                    addOnionToSks();
+                }
+                case 8: {
+                    replaceDefaultKeyserverWithUbuntu();
+                }
+            }
+
+            // write new preference version
+            mSharedPreferences.edit()
+                    .putInt(Constants.Pref.PREF_VERSION, Constants.Defaults.PREF_CURRENT_VERSION)
+                    .commit();
+        }
+    }
+
+    private void migrateToHkps() {
         ArrayList<HkpKeyserverAddress> servers = getKeyServers();
         ListIterator<HkpKeyserverAddress> it = servers.listIterator();
         while (it.hasNext()) {
@@ -466,20 +488,8 @@ public class Preferences {
         }
         setKeyServers(servers);
     }
-                // fall through
+
-                case 4: {
+    private void addOnionToSks() {
-                    setTheme(Constants.Pref.Theme.DEFAULT);
-                }
-                // fall through
-                case 5: {
-                    KeyserverSyncAdapterService.enableKeyserverSync(context);
-                }
-                // fall through
-                case 6: {
-                }
-                // fall through
-                case 7: {
-                    // add onion address to sks-keyservers.net
         ArrayList<HkpKeyserverAddress> servers = getKeyServers();
         ListIterator<HkpKeyserverAddress> it = servers.listIterator();
         while (it.hasNext()) {
@@ -496,17 +506,6 @@ public class Preferences {
         }
         setKeyServers(servers);
     }
-                case 8: {
-                    replaceDefaultKeyserverWithUbuntu();
-                }
-            }
-
-            // write new preference version
-            mSharedPreferences.edit()
-                    .putInt(Constants.Pref.PREF_VERSION, Constants.Defaults.PREF_CURRENT_VERSION)
-                    .commit();
-        }
-    }
 
     private void replaceDefaultKeyserverWithUbuntu() {
         ArrayList<HkpKeyserverAddress> servers = getKeyServers();