* Initialize the ContactSelectionListFragment with the selection from GroupCreateActivity, tackles #47.

* If contact is unselected in ContactSelectionListFragment, which was previously in the group, delete it from GroupCreateActivity, also.

src/org/thoughtcrime/securesms/ContactSelectionListFragment.java

@@ -61,6 +61,7 @@ import org.thoughtcrime.securesms.util.StickyHeaderDecoration;
 import org.thoughtcrime.securesms.util.Util;
 import org.thoughtcrime.securesms.util.ViewUtil;
 
+import java.util.ArrayList;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Set;
@@ -83,6 +84,7 @@ public class ContactSelectionListFragment extends    Fragment
   public static final String RECENTS               = "recents";
   public static final String SELECT_VERIFIED_EXTRA = "select_verified";
   public static final String FROM_SHARE_ACTIVITY_EXTRA = "from_share_activity";
+  public static final String PRESELECTED_CONTACTS = "preselected_contacts";
 
   private ApplicationDcContext dcContext;
 
@@ -243,6 +245,10 @@ public class ContactSelectionListFragment extends    Fragment
             isMulti(),
             true);
     selectedContacts = adapter.getSelectedContacts();
+    ArrayList<String> preselectedContacts = getActivity().getIntent().getStringArrayListExtra(PRESELECTED_CONTACTS);
+    if(preselectedContacts!=null) {
+      selectedContacts.addAll(preselectedContacts);
+    }
     recyclerView.setAdapter(adapter);
     recyclerView.addItemDecoration(new StickyHeaderDecoration(adapter, true, true));
   }

src/org/thoughtcrime/securesms/GroupCreateActivity.java

@@ -62,6 +62,7 @@ import org.thoughtcrime.securesms.util.task.ProgressDialogAsyncTask;
 import org.thoughtcrime.securesms.util.guava.Optional;
 
 import java.io.File;
+import java.util.ArrayList;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Set;
@@ -151,6 +152,7 @@ public class GroupCreateActivity extends PassphraseRequiredActionBarActivity
   }
 
   private void addSelectedContacts(@NonNull Recipient... recipients) {
+    getAdapter().clear();
     new AddMembersTask(this).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, recipients);
   }
 
@@ -421,6 +423,17 @@ public class GroupCreateActivity extends PassphraseRequiredActionBarActivity
     public void onClick(View v) {
       Intent intent = new Intent(GroupCreateActivity.this, ContactMultiSelectionActivity.class);
       intent.putExtra(ContactSelectionListFragment.SELECT_VERIFIED_EXTRA, verified);
+      if(editGroupChatId!=null) {
+        Recipient recipient = GroupCreateActivity.this.dcContext.getRecipient(ApplicationDcContext.RECIPIENT_TYPE_CHAT, editGroupChatId);
+        List<Recipient> participants = recipient.getParticipants();
+        ArrayList<String> preselectedContacts = new ArrayList<>();
+        for (Recipient p : participants) {
+          if(p.getAddress().isDcContact()) {
+            preselectedContacts.add(dcContext.getContact(p.getAddress().getDcContactId()).getAddr());
+          }
+        }
+        intent.putExtra(ContactSelectionListFragment.PRESELECTED_CONTACTS, preselectedContacts);
+      }
       startActivityForResult(intent, PICK_CONTACT);
     }
   }

src/org/thoughtcrime/securesms/util/SelectedRecipientsAdapter.java

@@ -67,6 +67,11 @@ public class SelectedRecipientsAdapter extends BaseAdapter {
     }
   }
 
+  public void clear() {
+    recipients.clear();
+    notifyDataSetChanged();
+  }
+
   public Set<Recipient> getRecipients() {
     final Set<Recipient> recipientSet = new HashSet<>(recipients.size());
     for (RecipientWrapper wrapper : recipients) {