如何在recyclerview中插入数据库数据后立即显示和更新数据库中的数据？

Question

我有一个录音机app.It把声音录成片段。我想在回收器视图中以另一个片段显示录制的项目。现在发生的情况是录音机工作正常。我已经看到数据被插入到数据库中。但录制的项目不会显示在回收器视图中。我想在数据插入时立即在recyclerview上显示记录的项目。

这是我的适配器类

    public class FileViewerAdapter extends RecyclerView.Adapter<FileViewerAdapter.RecordingViewHolder> implements OnDatabaseChangedListener
    {
        Context mContext;
        DBHelper mDatabase;
        RecordingItem item;
        LinearLayoutManager llm;
        private static final String LOG_TAG = "FileViewerAdapter";

        @Override
        public FileViewerAdapter.RecordingViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View v= LayoutInflater.from(parent.getContext()).inflate(R.layout.card_view,parent,false);
            mContext=parent.getContext();
            return new RecordingViewHolder(v);
        }

        public FileViewerAdapter(Context context, LinearLayoutManager linearLayoutManager) {
            super();
            mContext = context;
            mDatabase = new DBHelper(mContext);
            mDatabase.setOnDatabaseChangedListener(this);
            llm = linearLayoutManager;
        }

        @Override
        public void onBindViewHolder(final FileViewerAdapter.RecordingViewHolder holder, final int position) {
            item=getItem(position);
            int itemDuration=item.getLength();

            int minute= (int) TimeUnit.MILLISECONDS.toMinutes(itemDuration);
            int second= (int) ( TimeUnit.MILLISECONDS.toSeconds(itemDuration)-TimeUnit.MINUTES.toSeconds(minute));

            holder.vName.setText(item.getName());
            holder.vLength.setText(String.format("%02d:%02d", minute, second));
            holder.vDateAdded.setText(
                    DateUtils.formatDateTime(
                            mContext,
                            item.getTime(),
                            DateUtils.FORMAT_SHOW_DATE | DateUtils.FORMAT_NUMERIC_DATE | DateUtils.FORMAT_SHOW_TIME | DateUtils.FORMAT_SHOW_YEAR));

            holder.cardView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    try {
                        PlaybackFragment playbackFragment =
                                new PlaybackFragment().newInstance(getItem(holder.getPosition()));

                        FragmentManager fm = ((FragmentActivity) mContext)
                                .getSupportFragmentManager();

                        FragmentTransaction ft=fm.beginTransaction();
                        playbackFragment.show(fm,"dialog playback");
                        ft.commit();

                    }catch(Exception e)
                    {
                        Log.e(LOG_TAG,"exception",e);
                    }
                }
            });

            holder.cardView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {

                    ArrayList<String> arrayList=new ArrayList<String>() ;
                    arrayList.add(mContext.getString(R.string.dialog_file_share));
                    arrayList.add(mContext.getString(R.string.dialog_file_rename));
                    arrayList.add(mContext.getString(R.string.dialog_file_delete));

                    final CharSequence[] items= arrayList.toArray(new CharSequence[arrayList.size()]);

                    AlertDialog.Builder builder=new AlertDialog.Builder(mContext);
                    builder.setTitle(mContext.getString(R.string.dialog_title_options));
                    builder.setItems(items, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int position) {
                            if(position==0)
                            {
                                shareFileDialog(holder.getPosition());
                            }

                            if(position==1)
                            {
                                renameFileDialog(holder.getPosition());
                            }

                            if(position==2)
                            {
                                deleteFileDialog(holder.getPosition());
                            }
                        }
                    });

                    builder.setCancelable(true);
                    builder.setNegativeButton(mContext.getString(R.string.dialog_action_cancel), new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            dialog.cancel();
                        }
                    });
                    AlertDialog alert= builder.create();
                    alert.show();
                    return false;
                }

            });
        }

        @Override
        public int getItemCount() {
            return mDatabase.getCount();
        }
}

以下是片段类的'OnCreateView‘方法，其中将显示回收视图

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_file_viewer, container, false);

    RecyclerView mRecyclerView = (RecyclerView) v.findViewById(R.id.recycleView);
    mRecyclerView.setHasFixedSize(true);
    LinearLayoutManager llm = new LinearLayoutManager(getActivity());
    llm.setOrientation(LinearLayoutManager.VERTICAL);

    //newest to oldest order (database stores from oldest to newest)
    llm.setReverseLayout(true);
    llm.setStackFromEnd(true);

    mRecyclerView.setLayoutManager(llm);
    mRecyclerView.setItemAnimator(new DefaultItemAnimator());

    mFileViewerAdapter = new FileViewerAdapter(getActivity(), llm);
    mRecyclerView.setAdapter(mFileViewerAdapter);
    mFileViewerAdapter.notifyDataSetChanged();
    return v;
}

那么，问题出在哪里呢？请来人帮帮忙！

Answer 1

通过查看您的，我已经了解到，您没有正确地实现recyclerview适配器。

从DB中选择数据并将其存储在数组列表中，并将其传递给适配器，然后访问其中的数据并将其设置为VIews。

在将数据插入到数据库(我希望是SQLite)之后，您必须再次获取数据并将其添加到数组列表中，然后通过从活动/片段调用adapter.notifyDataSetChanged()；来更新回收视图。

通过这种方式，您可以实现干净且可维护的代码。