本文介绍了如何在实时Firebase中更新列表视图-Android的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

我在应用程序中实时更新朋友列表"(mListView)视图时遇到了一些麻烦,它似乎仅在启动时更新.我知道这是一个更新功能的问题,但我不知道该使用什么.

I have been having some trouble updating my Friends list(mListView) view in real time in the application, it only seems to update when it is launched. I know its a matter of an update function but i do not know what to use.

(我对Firebase和android还是很陌生,我仍在学习它们.)

(I'm rather new to firebase and android, and i'm still learning about them.)

这是代码:

private ListView mListView;
private ArrayList<String> mFriends;

private List<User> mUserList;

private UserListAdapter mAdapter;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_profile_friends, container, false);
    mSearchParam = (EditText) view.findViewById(R.id.searchFriends);
    mListView = (ListView) view.findViewById(R.id.lvProfileFriends);
    mPhotos = new ArrayList<>();
    mUserList = new ArrayList<>();
    mFriends = new ArrayList<>();



    DisplayFriends();

    return view;
}

private void DisplayFriends(){
    getFriends();
}


private void updateUsersList(){
    Log.d(TAG, "updateUsersList: updating users list");

    mAdapter = new UserListAdapter(getActivity(), R.layout.layout_user_listitem, mUserList);

    mListView.setAdapter(mAdapter);

    mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Log.d(TAG, "onItemClick: selected user: " + mUserList.get(position).toString());

            //navigate to profile activity
            Intent intent = new Intent(getActivity(), ViewProfileFragment.class);
            intent.putExtra(getString(R.string.calling_activity), getString(R.string.fragment_profile));
            intent.putExtra(getString(R.string.intent_user), mUserList.get(position));
            startActivity(intent);
        }
    });
}

private void updateFriendsList(){
    Log.d(TAG, "getPhotos: getting Friend(s)");
    DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
    for(int i = 0; i < mFriends.size(); i++){
        final int count = i;
        Query query = reference
                .child(getString(R.string.dbname_users))
                .orderByChild(getString(R.string.field_user_id))
                .equalTo(mFriends.get(i));
        query.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                for(DataSnapshot singleSnapshot : dataSnapshot.getChildren()){

                    mUserList.add(singleSnapshot.getValue(User.class));
                }
                if(count >= mFriends.size() - 1){
                    updateUsersList();
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });
    }
}


private void getFriends(){
    Log.d(TAG, "getFollowing: searching for FRIENDS **************************************");
    mFriends.clear();
    mUserList.clear();
    DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
    Query query = reference
            .child(getString(R.string.dbname_friends))
            .child(FirebaseAuth.getInstance().getCurrentUser().getUid());
    query.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
                Log.d(TAG, "onDataChange: found friend----------------**: " + singleSnapshot.getValue(User.class).toString());

                mFriends.add(singleSnapshot.child(getString(R.string.field_user_id)).getValue().toString());

                Log.d(TAG, "onDataChange: Freinds user id: " + mFriends.toString() );
            }

            updateFriendsList();
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

推荐答案

看看这个:

 DatabaseReference dref;
   ListView listview;
   ArrayList<String> list=new ArrayList<>();
   @Override
   protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.activity_main);
     listview=(ListView)findViewById(R.id.listview);
     final ArrayAdapter<String> adapter=new ArrayAdapter<String>(this,android.R.layout.simple_dropdown_item_1line,list);
     listview.setAdapter(adapter);
     dref=FirebaseDatabase.getInstance().getReference();
     dref.addChildEventListener(new ChildEventListener() {
       @Override
       public void onChildAdded(DataSnapshot dataSnapshot, String s) {
         list.add(dataSnapshot.getValue(String.class));
         adapter.notifyDataSetChanged();
       }
       @Override
       public void onChildChanged(DataSnapshot dataSnapshot, String s) {
       }
       @Override
       public void onChildRemoved(DataSnapshot dataSnapshot) {
         list.remove(dataSnapshot.getValue(String.class));
         adapter.notifyDataSetChanged();
       }
       @Override
       public void onChildMoved(DataSnapshot dataSnapshot, String s) {
       }
       @Override
       public void onCancelled(DatabaseError databaseError) {
       }
     });
   }

这篇关于如何在实时Firebase中更新列表视图-Android的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

07-23 01:21
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