Fix an NPE in WifiP2pSettings UI

The NPE happens becase we save a references to the group that is to be
deleted, when the confirmation dialog is being shown to the user. We lose
that reference if orientation is changed (because the UI creates a new
WifiP2pSettings to interact with).

The fix is to save the name of the group that is being deleted in
persistent store, and re-select the group based on that.

Bug: 9004915
Change-Id: I1387a5b17fa2773748f4c8b34adddfc9516cfcf3

src/com/android/settings/wifi/p2p/WifiP2pSettings.java

@@ -83,6 +83,7 @@ public class WifiP2pSettings extends SettingsPreferenceFragment
     private OnClickListener mDeleteGroupListener;
     private WifiP2pPeer mSelectedWifiPeer;
     private WifiP2pPersistentGroup mSelectedGroup;
+    private String mSelectedGroupName;
     private EditText mDeviceNameText;
 
     private boolean mWifiP2pEnabled;
@@ -102,6 +103,7 @@ public class WifiP2pSettings extends SettingsPreferenceFragment
 
     private static final String SAVE_DIALOG_PEER = "PEER_STATE";
     private static final String SAVE_DEVICE_NAME = "DEV_NAME";
+    private static final String SAVE_SELECTED_GROUP = "GROUP_NAME";
 
     private WifiP2pDevice mThisDevice;
     private WifiP2pDeviceList mPeers = new WifiP2pDeviceList();
@@ -160,6 +162,10 @@ public class WifiP2pSettings extends SettingsPreferenceFragment
         }
     };
 
+    public WifiP2pSettings() {
+        if (DBG) Log.d(TAG, "Creating WifiP2pSettings ...");
+    }
+
     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
         addPreferencesFromResource(R.xml.wifi_p2p_settings);
@@ -191,6 +197,9 @@ public class WifiP2pSettings extends SettingsPreferenceFragment
         if (savedInstanceState != null && savedInstanceState.containsKey(SAVE_DEVICE_NAME)) {
             mSavedDeviceName = savedInstanceState.getString(SAVE_DEVICE_NAME);
         }
+        if (savedInstanceState != null && savedInstanceState.containsKey(SAVE_SELECTED_GROUP)) {
+            mSelectedGroupName = savedInstanceState.getString(SAVE_SELECTED_GROUP);
+        }
 
         mRenameListener = new OnClickListener() {
             @Override
@@ -259,6 +268,8 @@ public class WifiP2pSettings extends SettingsPreferenceFragment
             public void onClick(DialogInterface dialog, int which) {
                 if (which == DialogInterface.BUTTON_POSITIVE) {
                     if (mWifiP2pManager != null) {
+                        if (mSelectedGroup != null) {
+                            if (DBG) Log.d(TAG, " deleting group " + mSelectedGroup.getGroupName());
                             mWifiP2pManager.deletePersistentGroup(mChannel,
                                     mSelectedGroup.getNetworkId(),
                                     new WifiP2pManager.ActionListener() {
@@ -269,8 +280,17 @@ public class WifiP2pSettings extends SettingsPreferenceFragment
                                     if (DBG) Log.d(TAG, " delete group fail " + reason);
                                 }
                             });
+                            mSelectedGroup = null;
+                        } else {
+                            if (DBG) Log.w(TAG, " No selected group to delete!" );
                         }
                     }
+                } else if (which == DialogInterface.BUTTON_NEGATIVE) {
+                    if (DBG) {
+                        Log.d(TAG, " forgetting selected group " + mSelectedGroup.getGroupName());
+                    }
+                    mSelectedGroup = null;
+                }
             }
         };
 
@@ -453,8 +473,8 @@ public class WifiP2pSettings extends SettingsPreferenceFragment
             AlertDialog dialog = new AlertDialog.Builder(getActivity())
                 .setMessage(getActivity().getString(stringId))
                 .setPositiveButton(getActivity().getString(R.string.dlg_ok), mDeleteGroupListener)
-                .setNegativeButton(getActivity().getString(R.string.dlg_cancel), null)
+                .setNegativeButton(getActivity().getString(R.string.dlg_cancel),
-                .create();
+                        mDeleteGroupListener).create();
             return dialog;
         }
         return null;
@@ -468,6 +488,9 @@ public class WifiP2pSettings extends SettingsPreferenceFragment
         if (mDeviceNameText != null) {
             outState.putString(SAVE_DEVICE_NAME, mDeviceNameText.getText().toString());
         }
+        if (mSelectedGroup != null) {
+            outState.putString(SAVE_SELECTED_GROUP, mSelectedGroup.getGroupName());
+        }
     }
 
     private void handlePeersChanged() {
@@ -488,7 +511,20 @@ public class WifiP2pSettings extends SettingsPreferenceFragment
 
         for (WifiP2pGroup group: groups.getGroupList()) {
             if (DBG) Log.d(TAG, " group " + group);
-            mPersistentGroup.addPreference(new WifiP2pPersistentGroup(getActivity(), group));
+            WifiP2pPersistentGroup wppg = new WifiP2pPersistentGroup(getActivity(), group);
+            mPersistentGroup.addPreference(wppg);
+            if (wppg.getGroupName().equals(mSelectedGroupName)) {
+                if (DBG) Log.d(TAG, "Selecting group " + wppg.getGroupName());
+                mSelectedGroup = wppg;
+                mSelectedGroupName = null;
+            }
+        }
+        if (mSelectedGroupName != null) {
+            // Looks like there's a dialog pending getting user confirmation to delete the
+            // selected group. When user hits OK on that dialog, we won't do anything; but we
+            // shouldn't be in this situation in first place, because these groups are persistent
+            // groups and they shouldn't just get deleted!
+            Log.w(TAG, " Selected group " + mSelectedGroupName + " disappered on next query ");
         }
     }