android - 更新数据库后更新listView？

Question

我有一个书籍 ListView ，我通过单击项目及其作品来更新 ListView ，但是我有重复的项目，旧的和新的。在我的数据库中我只有新数据。我怎样才能修改我的 ListView ？我正在使用 FireBase 数据库。

更新我的 Activity 来源:

public class ListOfMyBookActivity extends AppCompatActivity  {

//The elements are initialized here

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list_of_my_book);

        listView = (ListView) findViewById(R.id.list_book);

        feedItems = new ArrayList<Book>();
        dataBD= FirebaseDatabase.getInstance();
        dataBaseD=FirebaseDatabase.getInstance();
        updateDB=FirebaseDatabase.getInstance();
        ref = dataBD.getReference("books");
        refdelete=dataBaseD.getReference("books");
        refUpdate=updateDB.getReference("books");
        auth = FirebaseAuth.getInstance();
        mDatabase = FirebaseDatabase.getInstance().getReference("books");


            ref.orderByChild("date_creation").limitToLast(10).addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {



                    List<String> list = new ArrayList<String>();
                    for (DataSnapshot dataSnap : dataSnapshot.getChildren()) {

                        Book valueBook = dataSnap.getValue(Book.class);
                        keyId = dataSnap.getKey();

                        String userBd = valueBook.getId_user();
                        if (userBd.equalsIgnoreCase(id_user)) {
                            String titreLivreToDisplay = valueBook.getNom_livre();
                            String descLivreToDisplay = valueBook.getDesc_livre();
                            String prixLivreToDisplay = valueBook.getPrix_livre();
                            String timeToDisplay = valueBook.getDate_creation();
                            String filePathToDiplay = valueBook.getChemin_image();
                            String villeToDisplay = valueBook.getVille_livre();
                            String typeAnnToDisplat = valueBook.getType_annonce_selected();
                            String bookid = valueBook.getId_book();



                            item = new Book();
                            item.setNom_livre(titreLivreToDisplay);
                            item.setDesc_livre(descLivreToDisplay);
                            item.setPrix_livre(prixLivreToDisplay);
                            item.setDate_creation(timeToDisplay);
                            item.setChemin_image(filePathToDiplay);
                            item.setVille_livre(villeToDisplay);
                            item.setType_annonce_selected(typeAnnToDisplat);
                            item.setId_book(bookid);
                            item.setKeyIdNode(keyId);

                            feedItems.add(item);


                        }

                        Collections.reverse(feedItems);


                        listAdapter = new MyBookListAdapter(ListOfMyBookActivity.this, feedItems);

                        listView.setAdapter(listAdapter);

                        listView.setOnItemClickListener(myClickListener);

                        listAdapter.notifyDataSetChanged();


                    }}



            });


    }


    public AdapterView.OnItemClickListener myClickListener = new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1,
                                final int position, long arg3) {
            deleteItem = position;
            // The AlertDialog is created programmatically
            AlertDialog.Builder alert = new AlertDialog.Builder(arg1.getContext());

            nameBookEdtDlg.setText(nom);
            descBookEdtDlg.setText(desc);
            prixBookEdtDlg.setText(prix);

                alert.setPositiveButton("Update ",
                        new DialogInterface.OnClickListener()

                {
                    public void onClick (DialogInterface dialog,
                    int whichButton){


                    Query query = refUpdate.orderByChild("id_book").equalTo(bookID);

                    query.addListenerForSingleValueEvent(new ValueEventListener() {

                        @Override
                        public void onDataChange(DataSnapshot dataSnapshot) {

                            prixSt=prixBookEdtDlg.getText().toString();
                            descSt=descBookEdtDlg.getText().toString();
                            namSt=nameBookEdtDlg.getText().toString();


                            Map<String, Object> result = new HashMap<String, Object>();
                            result.put("nom_livre", namSt);
                            result.put("desc_livre", descSt);
                            result.put("prix_livre", prixSt);
                            result.put("date_creation", currentDateandTimeUpdate);
                            refUpdate.child(keyId).updateChildren(result);

                            listAdapter.notifyDataSetChanged();

                        } });

            AlertDialog alertDialog = alert.create();

                try{alertDialog.show();} } };}
                }

}

适配器:

public class MyBookListAdapter extends BaseAdapter {


    public MyBookListAdapter( ListOfMyBookActivity listMyBooks, List<Book> feedItemsBooks) {
        this.activity = listMyBooks;
        this.feedItemsBooks = feedItemsBooks;
    }
    @Override
    public int getCount() {
        return feedItemsBooks.size();
    }

    @Override
    public Object getItem(int location) {
        return feedItemsBooks.get(location);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, final ViewGroup parent) {
        final int pos = position;

        if (inflater == null) {
            inflater = (LayoutInflater) activity
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.feed_list_item, null);

        }
        storageDisplayImg = FirebaseStorage.getInstance();
        auth = FirebaseAuth.getInstance();
        FirebaseUser userConnect = auth.getCurrentUser();
        String id_user = userConnect.getUid();
        mFirebaseInstance = FirebaseDatabase.getInstance();
        mFirebaseDatabase = mFirebaseInstance.getReference("books");


        final ImageView profilePic = (ImageView) convertView.findViewById(R.id.book_picture_display_myBook);
        name = (TextView) convertView.findViewById(R.id.name_book_display_myBook);
        TextView timestamp = (TextView) convertView.findViewById(R.id.timestamp_myBook);
        statusMsg = (TextView) convertView.findViewById(R.id.desc_display_myBook);
        prix = (TextView) convertView.findViewById(R.id.prix_display_myBook);
        TextView ville = (TextView) convertView.findViewById(R.id.ville_display_myBook);
        TextView typeCat = (TextView) convertView.findViewById(R.id.type_ann_to_display_myBook);


        Book item = feedItemsBooks.get(position);



        idLivreListAdapter=item.getId_book();

        name.setText(item.getNom_livre());

        if (!TextUtils.isEmpty(item.getDate_creation())) {
            timestamp.setText(item.getDate_creation());
            timestamp.setVisibility(View.VISIBLE);
        } else {
            timestamp.setVisibility(View.GONE);
        }

        if (!TextUtils.isEmpty(item.getDesc_livre())) {
            statusMsg.setText(item.getDesc_livre());
            statusMsg.setVisibility(View.VISIBLE);
        } else {
            statusMsg.setVisibility(View.GONE);
        }

        if (!TextUtils.isEmpty(item.getType_annonce_selected())) {
            typeCat.setText(item.getType_annonce_selected());
            typeCat.setVisibility(View.VISIBLE);
        } else {
            typeCat.setVisibility(View.GONE);
        }


        if (item.getPrix_livre() != null) {
            prix.setText(item.getPrix_livre() + " DH");
            prix.setVisibility(View.VISIBLE);
        } else {
            prix.setVisibility(View.GONE);
        }

        if (item.getVille_livre() != null) {

            ville.setText(item.getVille_livre());
            ville.setVisibility(View.VISIBLE);
        } else {
            ville.setVisibility(View.GONE);
        }

        storageRef = storageDisplayImg.getReferenceFromUrl(item.getChemin_image());
        Log.e(" ", " storageRef " + storageRef.toString());

        if (item.getChemin_image() != null && id_user != null) {


            Glide.with(convertView.getContext())
                    .using(new FirebaseImageLoader())
                    .load(storageRef)
                    .into(profilePic);
            profilePic.setVisibility(View.VISIBLE);

        } else {
            profilePic.setVisibility(View.GONE);
        }


        return convertView;
    }



}

我的问题没有重复我尝试了建议的解决方案，但它不起作用。

Answer 1

不确定这是否是您的问题，但大多数 firebase 代码并非都是必需的...

请注意，您调用了 getNom_livre(和其他)，然后使用完全相同的值调用了 setNom_livre(和其他)？
当您已经拥有一本新书时，您也可以制作一本。

Book valueBook = dataSnap.getValue(Book.class); // This is a Book
keyId = dataSnap.getKey();

String userBd = valueBook.getId_user();
if (userBd.equalsIgnoreCase(id_user)) {
    String titreLivreToDisplay = valueBook.getNom_livre();
    ...

    item = new Book(); // Why do you need a new one?
    item.setNom_livre(titreLivreToDisplay);
    ... 

    feedItems.add(item);
}

首先，您应该将它移到 firebase 方法之前。无需在每次数据更新时重新创建适配器。

listAdapter = new MyBookListAdapter(ListOfMyBookActivity.this, feedItems);
listView.setAdapter(listAdapter);
listView.setOnItemClickListener(myClickListener);

ref.orderByChild("date_creation")...

but i have duplicate item , the old one and the new one

您只需清除适配器即可删除旧数据并添加新数据

ref.orderByChild("date_creation")
    .limitToLast(10)
    .addValueEventListener(new ValueEventListener() {
         @Override
         public void onDataChange(DataSnapshot dataSnapshot) {
             // Remove old data
             feedItems.clear(); 

             // Add new data
             for (DataSnapshot dataSnap : dataSnapshot.getChildren()) {

                 Book valueBook = dataSnap.getValue(Book.class);
                 keyId = dataSnap.getKey();

                  String userBd = valueBook.getId_user();
                  if (userBd.equalsIgnoreCase(id_user)) {
                      valueBook.setKeyIdNode(keyId);
                      feedItems.add(valueBook);
                  }
             }
             Collections.reverse(feedItems);
             listAdapter.notifyDataSetChanged(); // Tell adapter of new data