diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 189e1b6..0c4183d 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -422,7 +422,7 @@
             <meta-data android:name="com.android.settings.PRIMARY_PROFILE_CONTROLLED"
                 android:value="true" />
             <meta-data android:name="com.android.settings.FRAGMENT_CLASS"
-                       android:value="com.android.settings.network.ApnSettings" />
+                       android:value="com.android.settings.network.apn.ApnSettings" />
         </activity>
 
         <!-- Keep compatibility with old shortcuts. -->
@@ -2003,7 +2003,7 @@
                 <data android:mimeType="vnd.android.cursor.dir/telephony-carrier" />
             </intent-filter>
             <meta-data android:name="com.android.settings.FRAGMENT_CLASS"
-                       android:value="com.android.settings.network.ApnEditor" />
+                       android:value="com.android.settings.network.apn.ApnEditor" />
         </activity>
 
         <activity
diff --git a/src/com/android/settings/ResetNetworkConfirm.java b/src/com/android/settings/ResetNetworkConfirm.java
index 53fe369..97139c4 100644
--- a/src/com/android/settings/ResetNetworkConfirm.java
+++ b/src/com/android/settings/ResetNetworkConfirm.java
@@ -49,7 +49,7 @@
 
 import com.android.settings.core.InstrumentedFragment;
 import com.android.settings.enterprise.ActionDisabledByAdminDialogHelper;
-import com.android.settings.network.ApnSettings;
+import com.android.settings.network.apn.ApnSettings;
 import com.android.settingslib.RestrictedLockUtilsInternal;
 
 /**
diff --git a/src/com/android/settings/core/gateway/SettingsGateway.java b/src/com/android/settings/core/gateway/SettingsGateway.java
index 4a5d71a..8934034 100644
--- a/src/com/android/settings/core/gateway/SettingsGateway.java
+++ b/src/com/android/settings/core/gateway/SettingsGateway.java
@@ -108,11 +108,11 @@
 import com.android.settings.localepicker.LocaleListEditor;
 import com.android.settings.location.LocationSettings;
 import com.android.settings.location.ScanningSettings;
-import com.android.settings.network.ApnEditor;
-import com.android.settings.network.ApnSettings;
 import com.android.settings.network.MobileNetworkListFragment;
 import com.android.settings.network.NetworkDashboardFragment;
 import com.android.settings.network.NetworkProviderSettings;
+import com.android.settings.network.apn.ApnEditor;
+import com.android.settings.network.apn.ApnSettings;
 import com.android.settings.nfc.AndroidBeam;
 import com.android.settings.nfc.PaymentSettings;
 import com.android.settings.notification.ConfigureNotificationSettings;
diff --git a/src/com/android/settings/network/ApnEditor.java b/src/com/android/settings/network/apn/ApnEditor.java
similarity index 97%
rename from src/com/android/settings/network/ApnEditor.java
rename to src/com/android/settings/network/apn/ApnEditor.java
index a852fd6..8f6d64d 100644
--- a/src/com/android/settings/network/ApnEditor.java
+++ b/src/com/android/settings/network/apn/ApnEditor.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.settings.network;
+package com.android.settings.network.apn;
 
 import android.app.Dialog;
 import android.app.settings.SettingsEnums;
@@ -53,6 +53,7 @@
 import com.android.settings.R;
 import com.android.settings.SettingsPreferenceFragment;
 import com.android.settings.core.instrumentation.InstrumentedDialogFragment;
+import com.android.settings.network.ProxySubscriptionManager;
 import com.android.settingslib.utils.ThreadUtils;
 
 import java.util.Arrays;
@@ -61,20 +62,21 @@
 import java.util.Objects;
 import java.util.Set;
 
+/** Use to edit apn settings. */
 public class ApnEditor extends SettingsPreferenceFragment
         implements OnPreferenceChangeListener, OnKeyListener {
 
-    private final static String TAG = ApnEditor.class.getSimpleName();
-    private final static boolean VDBG = false;   // STOPSHIP if true
+    private static final String TAG = ApnEditor.class.getSimpleName();
+    private static final boolean VDBG = false;   // STOPSHIP if true
 
-    private final static String KEY_AUTH_TYPE = "auth_type";
+    private static final String KEY_AUTH_TYPE = "auth_type";
     private static final String KEY_APN_TYPE = "apn_type";
-    private final static String KEY_PROTOCOL = "apn_protocol";
-    private final static String KEY_ROAMING_PROTOCOL = "apn_roaming_protocol";
-    private final static String KEY_CARRIER_ENABLED = "carrier_enabled";
-    private final static String KEY_BEARER_MULTI = "bearer_multi";
-    private final static String KEY_MVNO_TYPE = "mvno_type";
-    private final static String KEY_PASSWORD = "apn_password";
+    private static final String KEY_PROTOCOL = "apn_protocol";
+    private static final String KEY_ROAMING_PROTOCOL = "apn_roaming_protocol";
+    private static final String KEY_CARRIER_ENABLED = "carrier_enabled";
+    private static final String KEY_BEARER_MULTI = "bearer_multi";
+    private static final String KEY_MVNO_TYPE = "mvno_type";
+    private static final String KEY_PASSWORD = "apn_password";
 
     private static final int MENU_DELETE = Menu.FIRST;
     private static final int MENU_SAVE = Menu.FIRST + 1;
@@ -213,7 +215,7 @@
             Telephony.Carriers.MCC, // 9
             Telephony.Carriers.MNC, // 10
             Telephony.Carriers.NUMERIC, // 11
-            Telephony.Carriers.MMSPROXY,// 12
+            Telephony.Carriers.MMSPROXY, // 12
             Telephony.Carriers.MMSPORT, // 13
             Telephony.Carriers.AUTH_TYPE, // 14
             Telephony.Carriers.TYPE, // 15
@@ -583,7 +585,7 @@
                 }
             }
 
-            if (mBearerInitialVal != 0 && bearers.contains("" + mBearerInitialVal) == false) {
+            if (mBearerInitialVal != 0 && !bearers.contains("" + mBearerInitialVal)) {
                 // add mBearerInitialVal to bearers
                 bearers.add("" + mBearerInitialVal);
             }
@@ -699,7 +701,7 @@
                             && Arrays.asList(mReadOnlyApnFields)
                             .contains(Telephony.Carriers.MVNO_MATCH_DATA));
             mMvnoMatchData.setEnabled(!mvnoMatchDataUneditable && mvnoIndex != 0);
-            if (newValue != null && newValue.equals(oldValue) == false) {
+            if (newValue != null && !newValue.equals(oldValue)) {
                 if (values[mvnoIndex].equals("SPN")) {
                     TelephonyManager telephonyManager = (TelephonyManager)
                             getContext().getSystemService(TelephonyManager.class);
@@ -739,7 +741,9 @@
             }
         }
     }
-
+    /**
+     * Callback when preference status changed.
+     */
     public boolean onPreferenceChange(Preference preference, Object newValue) {
         String key = preference.getKey();
         if (KEY_AUTH_TYPE.equals(key)) {
@@ -1342,8 +1346,13 @@
         }
     }
 
+    /**
+     * Dialog of error message.
+     */
     public static class ErrorDialog extends InstrumentedDialogFragment {
-
+        /**
+         * Show error dialog.
+         */
         public static void showError(ApnEditor editor) {
             final ErrorDialog dialog = new ErrorDialog();
             dialog.setTargetFragment(editor, 0);
diff --git a/src/com/android/settings/network/ApnPreference.java b/src/com/android/settings/network/apn/ApnPreference.java
similarity index 82%
rename from src/com/android/settings/network/ApnPreference.java
rename to src/com/android/settings/network/apn/ApnPreference.java
index 63e2838..f277db0 100755
--- a/src/com/android/settings/network/ApnPreference.java
+++ b/src/com/android/settings/network/apn/ApnPreference.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.settings.network;
+package com.android.settings.network.apn;
 
 import android.content.ContentUris;
 import android.content.Context;
@@ -40,7 +40,7 @@
  */
 public class ApnPreference extends Preference implements CompoundButton.OnCheckedChangeListener,
         View.OnClickListener {
-    final static String TAG = "ApnPreference";
+    private static final  String TAG = "ApnPreference";
 
     private int mSubId = SubscriptionManager.INVALID_SUBSCRIPTION_ID;
 
@@ -65,8 +65,8 @@
         this(context, null);
     }
 
-    private static String mSelectedKey = null;
-    private static CompoundButton mCurrentChecked = null;
+    private static String sSelectedKey = null;
+    private static CompoundButton sCurrentChecked = null;
     private boolean mProtectFromCheckedChange = false;
     private boolean mSelectable = true;
     private boolean mHideDetails = false;
@@ -84,10 +84,10 @@
             if (mSelectable) {
                 rb.setOnCheckedChangeListener(this);
 
-                final boolean isChecked = getKey().equals(mSelectedKey);
+                final boolean isChecked = getKey().equals(sSelectedKey);
                 if (isChecked) {
-                    mCurrentChecked = rb;
-                    mSelectedKey = getKey();
+                    sCurrentChecked = rb;
+                    sSelectedKey = getKey();
                 }
 
                 mProtectFromCheckedChange = true;
@@ -100,14 +100,23 @@
         }
     }
 
+    /**
+     * Return the preference is checked or not.
+     */
     public boolean isChecked() {
-        return getKey().equals(mSelectedKey);
+        return getKey().equals(sSelectedKey);
     }
 
+    /**
+     * Set preference checked.
+     */
     public void setChecked() {
-        mSelectedKey = getKey();
+        sSelectedKey = getKey();
     }
 
+    /**
+     * Change the preference status.
+     */
     public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
         Log.i(TAG, "ID: " + getKey() + " :" + isChecked);
         if (mProtectFromCheckedChange) {
@@ -115,15 +124,15 @@
         }
 
         if (isChecked) {
-            if (mCurrentChecked != null) {
-                mCurrentChecked.setChecked(false);
+            if (sCurrentChecked != null) {
+                sCurrentChecked.setChecked(false);
             }
-            mCurrentChecked = buttonView;
-            mSelectedKey = getKey();
-            callChangeListener(mSelectedKey);
+            sCurrentChecked = buttonView;
+            sSelectedKey = getKey();
+            callChangeListener(sSelectedKey);
         } else {
-            mCurrentChecked = null;
-            mSelectedKey = null;
+            sCurrentChecked = null;
+            sSelectedKey = null;
         }
     }
 
@@ -161,6 +170,9 @@
         mSubId = subId;
     }
 
+    /**
+     * Hide details
+     */
     public void setHideDetails() {
         mHideDetails = true;
     }
diff --git a/src/com/android/settings/network/ApnSettings.java b/src/com/android/settings/network/apn/ApnSettings.java
similarity index 96%
rename from src/com/android/settings/network/ApnSettings.java
rename to src/com/android/settings/network/apn/ApnSettings.java
index f7617fc..f5bb1be 100755
--- a/src/com/android/settings/network/ApnSettings.java
+++ b/src/com/android/settings/network/apn/ApnSettings.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.settings.network;
+package com.android.settings.network.apn;
 
 import android.app.Activity;
 import android.app.Dialog;
@@ -56,19 +56,21 @@
 
 import com.android.settings.R;
 import com.android.settings.RestrictedSettingsFragment;
+import com.android.settings.network.SubscriptionUtil;
 import com.android.settingslib.RestrictedLockUtils.EnforcedAdmin;
 
 import java.util.ArrayList;
 
+/** Handle each different apn setting. */
 public class ApnSettings extends RestrictedSettingsFragment
         implements Preference.OnPreferenceChangeListener {
     static final String TAG = "ApnSettings";
 
     public static final String EXTRA_POSITION = "position";
     public static final String RESTORE_CARRIERS_URI =
-        "content://telephony/carriers/restore";
+            "content://telephony/carriers/restore";
     public static final String PREFERRED_APN_URI =
-        "content://telephony/carriers/preferapn";
+            "content://telephony/carriers/preferapn";
 
     public static final String APN_ID = "apn_id";
     public static final String SUB_ID = "sub_id";
@@ -104,7 +106,7 @@
     private static final Uri DEFAULTAPN_URI = Uri.parse(RESTORE_CARRIERS_URI);
     private static final Uri PREFERAPN_URI = Uri.parse(PREFERRED_APN_URI);
 
-    private static boolean mRestoreDefaultApnMode;
+    private boolean mRestoreDefaultApnMode;
 
     private UserManager mUserManager;
     private TelephonyManager mTelephonyManager;
@@ -385,13 +387,12 @@
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         switch (item.getItemId()) {
-        case MENU_NEW:
-            addNewApn();
-            return true;
-
-        case MENU_RESTORE:
-            restoreDefaultApn();
-            return true;
+            case MENU_NEW:
+                addNewApn();
+                return true;
+            case MENU_RESTORE:
+                restoreDefaultApn();
+                return true;
         }
         return super.onOptionsItemSelected(item);
     }
@@ -451,8 +452,7 @@
             mRestoreApnUiHandler = new RestoreApnUiHandler();
         }
 
-        if (mRestoreApnProcessHandler == null ||
-            mRestoreDefaultApnThread == null) {
+        if (mRestoreApnProcessHandler == null || mRestoreDefaultApnThread == null) {
             mRestoreDefaultApnThread = new HandlerThread(
                     "Restore default APN Handler: Process Thread");
             mRestoreDefaultApnThread.start();
@@ -503,7 +503,7 @@
     private class RestoreApnProcessHandler extends Handler {
         private Handler mRestoreApnUiHandler;
 
-        public RestoreApnProcessHandler(Looper looper, Handler restoreApnUiHandler) {
+        RestoreApnProcessHandler(Looper looper, Handler restoreApnUiHandler) {
             super(looper);
             this.mRestoreApnUiHandler = restoreApnUiHandler;
         }
diff --git a/src/com/android/settings/network/telephony/ApnPreferenceController.java b/src/com/android/settings/network/telephony/ApnPreferenceController.java
index 8442de2..0e0e5d1 100644
--- a/src/com/android/settings/network/telephony/ApnPreferenceController.java
+++ b/src/com/android/settings/network/telephony/ApnPreferenceController.java
@@ -32,7 +32,7 @@
 import androidx.preference.PreferenceScreen;
 
 import com.android.settings.SettingsActivity;
-import com.android.settings.network.ApnSettings;
+import com.android.settings.network.apn.ApnSettings;
 import com.android.settingslib.RestrictedLockUtilsInternal;
 import com.android.settingslib.RestrictedPreference;
 import com.android.settingslib.core.lifecycle.LifecycleObserver;
diff --git a/tests/robotests/assets/exempt_not_implementing_index_provider b/tests/robotests/assets/exempt_not_implementing_index_provider
index 80e179a..97fe120 100644
--- a/tests/robotests/assets/exempt_not_implementing_index_provider
+++ b/tests/robotests/assets/exempt_not_implementing_index_provider
@@ -54,8 +54,8 @@
 com.android.settings.inputmethod.SpellCheckersSettings
 com.android.settings.location.LocationPersonalSettings
 com.android.settings.location.LocationWorkProfileSettings
-com.android.settings.network.ApnEditor
-com.android.settings.network.ApnSettings
+com.android.settings.network.apn.ApnEditor
+com.android.settings.network.apn.ApnSettings
 com.android.settings.network.telephony.NetworkSelectSettings
 com.android.settings.notification.app.AppNotificationSettings
 com.android.settings.notification.app.ChannelNotificationSettings
diff --git a/tests/robotests/src/com/android/settings/network/ApnEditorTest.java b/tests/robotests/src/com/android/settings/network/apn/ApnEditorTest.java
similarity index 97%
rename from tests/robotests/src/com/android/settings/network/ApnEditorTest.java
rename to tests/robotests/src/com/android/settings/network/apn/ApnEditorTest.java
index 7ec1174..0a430cd 100644
--- a/tests/robotests/src/com/android/settings/network/ApnEditorTest.java
+++ b/tests/robotests/src/com/android/settings/network/apn/ApnEditorTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.settings.network;
+package com.android.settings.network.apn;
 
 import static com.google.common.truth.Truth.assertThat;
 
@@ -46,7 +46,8 @@
 import androidx.preference.SwitchPreference;
 
 import com.android.settings.R;
-import com.android.settings.network.ApnEditor.ApnData;
+import com.android.settings.network.ProxySubscriptionManager;
+import com.android.settings.network.apn.ApnEditor.ApnData;
 import com.android.settings.testutils.shadow.ShadowFragment;
 
 import org.junit.Before;
@@ -93,7 +94,7 @@
     private static final int CURSOR_INTEGER_INDEX = 0;
     private static final int CURSOR_STRING_INDEX = 1;
 
-    private static final Uri mApnUri = Uri.parse("Apn://row/1");
+    private static final Uri APN_URI = Uri.parse("Apn://row/1");
 
     @Mock
     private Cursor mCursor;
@@ -382,7 +383,7 @@
     public void testApnData_invalidIntegerType_throwsInvalidTypeException() {
         // GIVEN a ApnData constructed from cursor
         initCursor();
-        final ApnData data = new ApnData(mApnUri, mCursor);
+        final ApnData data = new ApnData(APN_URI, mCursor);
 
         // WHEN get a string from an integer column
         // THEN the InvalidTypeException is threw
@@ -393,7 +394,7 @@
     public void testApnData_invalidStringType_throwsInvalidTypeException() {
         // GIVEN a ApnData constructed from cursor
         initCursor();
-        final ApnData data = new ApnData(mApnUri, mCursor);
+        final ApnData data = new ApnData(APN_URI, mCursor);
 
         // WHEN get a integer from a string column
         // THEN the InvalidTypeException is threw
@@ -404,7 +405,7 @@
     public void testApnData_validIntegerType_returnCorrectValue() {
         // GIVEN a ApnData constructed from cursor
         initCursor();
-        final ApnData data = new ApnData(mApnUri, mCursor);
+        final ApnData data = new ApnData(APN_URI, mCursor);
 
         // WHEN get integer from an integer column
         final int val = data.getInteger(CURSOR_INTEGER_INDEX);
@@ -417,7 +418,7 @@
     public void testApnData_validStringType_returnCorrectValue() {
         // GIVEN a ApnData constructed from cursor
         initCursor();
-        final ApnData data = new ApnData(mApnUri, mCursor);
+        final ApnData data = new ApnData(APN_URI, mCursor);
 
         // WHEN get string from a string column
         final String str = data.getString(CURSOR_STRING_INDEX);
diff --git a/tests/robotests/src/com/android/settings/network/telephony/ApnPreferenceControllerTest.java b/tests/robotests/src/com/android/settings/network/telephony/ApnPreferenceControllerTest.java
index e03da10..566ea8b 100644
--- a/tests/robotests/src/com/android/settings/network/telephony/ApnPreferenceControllerTest.java
+++ b/tests/robotests/src/com/android/settings/network/telephony/ApnPreferenceControllerTest.java
@@ -34,7 +34,7 @@
 import android.telephony.SubscriptionManager;
 import android.telephony.TelephonyManager;
 
-import com.android.settings.network.ApnSettings;
+import com.android.settings.network.apn.ApnSettings;
 import com.android.settingslib.RestrictedPreference;
 
 import org.junit.Before;
diff --git a/tests/unit/src/com/android/settings/network/telephony/ApnPreferenceControllerTest.java b/tests/unit/src/com/android/settings/network/telephony/ApnPreferenceControllerTest.java
index 264abd0..1f3031a 100644
--- a/tests/unit/src/com/android/settings/network/telephony/ApnPreferenceControllerTest.java
+++ b/tests/unit/src/com/android/settings/network/telephony/ApnPreferenceControllerTest.java
@@ -37,7 +37,7 @@
 import androidx.test.core.app.ApplicationProvider;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 
-import com.android.settings.network.ApnSettings;
+import com.android.settings.network.apn.ApnSettings;
 import com.android.settingslib.RestrictedPreference;
 
 import org.junit.Before;