[Settings] Code refactor

Move some work out of constructor of
EnabledNetworkModePreferenceController.
Which could avoid callbacks before init() been invoked.

Bug: 141833767
Test: make RunSettingsRoboTests -j
ROBOTEST_FILTER=Enhanced4gBasePreferenceControllerTest
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=EnabledNetworkModePreferenceControllerTest
Change-Id: I11f25d130a746c75184a21a8991177b02ad237f0

Change-Id: I6aa58a8d9d15b1524bf03f425e3eae3a0254593e

src/com/android/settings/network/telephony/EnabledNetworkModePreferenceController.java

@@ -61,19 +61,6 @@ public class EnabledNetworkModePreferenceController extends
 
     public EnabledNetworkModePreferenceController(Context context, String key) {
         super(context, key);
-        mPreferredNetworkModeObserver = new PreferredNetworkModeContentObserver(
-                new Handler(Looper.getMainLooper()));
-        mPreferredNetworkModeObserver.setPreferredNetworkModeChangedListener(
-                () -> updatePreference());
-    }
-
-    private void updatePreference() {
-        if (mPreferenceScreen != null) {
-            displayPreference(mPreferenceScreen);
-        }
-        if (mPreference != null) {
-            updateState(mPreference);
-        }
     }
 
     @Override
@@ -100,11 +87,17 @@ public class EnabledNetworkModePreferenceController extends
 
     @OnLifecycleEvent(ON_START)
     public void onStart() {
+        if (mPreferredNetworkModeObserver == null) {
+            return;
+        }
         mPreferredNetworkModeObserver.register(mContext, mSubId);
     }
 
     @OnLifecycleEvent(ON_STOP)
     public void onStop() {
+        if (mPreferredNetworkModeObserver == null) {
+            return;
+        }
         mPreferredNetworkModeObserver.unregister(mContext);
     }
 
@@ -151,9 +144,25 @@ public class EnabledNetworkModePreferenceController extends
         mCarrierConfigManager = mContext.getSystemService(CarrierConfigManager.class);
         mBuilder = new PreferenceEntriesBuilder(mContext, mSubId);
 
+        if (mPreferredNetworkModeObserver == null) {
+            mPreferredNetworkModeObserver = new PreferredNetworkModeContentObserver(
+                    new Handler(Looper.getMainLooper()));
+            mPreferredNetworkModeObserver.setPreferredNetworkModeChangedListener(
+                    () -> updatePreference());
+        }
+
         lifecycle.addObserver(this);
     }
 
+    private void updatePreference() {
+        if (mPreferenceScreen != null) {
+            displayPreference(mPreferenceScreen);
+        }
+        if (mPreference != null) {
+            updateState(mPreference);
+        }
+    }
+
     private final static class PreferenceEntriesBuilder {
         private CarrierConfigManager mCarrierConfigManager;
         private Context mContext;

src/com/android/settings/network/telephony/Enhanced4gBasePreferenceController.java

@@ -69,10 +69,13 @@ public class Enhanced4gBasePreferenceController extends TelephonyTogglePreferenc
     public Enhanced4gBasePreferenceController(Context context, String key) {
         super(context, key);
         m4gLteListeners = new ArrayList<>();
-        mPhoneStateListener = new PhoneCallStateListener();
     }
 
     public Enhanced4gBasePreferenceController init(int subId) {
+        if (mPhoneStateListener == null) {
+            mPhoneStateListener = new PhoneCallStateListener();
+        }
+
         if (mSubId == subId) {
             return this;
         }
@@ -122,11 +125,17 @@ public class Enhanced4gBasePreferenceController extends TelephonyTogglePreferenc
 
     @Override
     public void onStart() {
+        if (mPhoneStateListener == null) {
+            return;
+        }
         mPhoneStateListener.register(mContext, mSubId);
     }
 
     @Override
     public void onStop() {
+        if (mPhoneStateListener == null) {
+            return;
+        }
         mPhoneStateListener.unregister();
     }