问题
Image
I have an EditText which adds items to this RecyclerView and to the Realm DB. That works fine. The problem is that I don't know how to remove those items from both the RecyclerView and from the Realm DB. Should this be done on the Fragment or on the adapter? And how? Thanks!
There is an image on top showing a screenshot of the app.
Here is the Fragment where the RecyclerView is:
public class FragmentMyList extends Fragment{
private RecyclerView recyclerView;
private EditText editTxt;
private FloatingActionButton btn;
private Item item;
private ArrayList<Item> itemList;
private AdapterItemsRecycler adapterItemsRecycler;
private Realm realm;
RealmResults<Item> results;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View vistaADevolver = inflater.inflate(R.layout.fragment_my_list, container, false);
getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
Realm.init(getContext());
realm = Realm.getDefaultInstance();
editTxt = (EditText)vistaADevolver.findViewById(R.id.editText);
btn = (FloatingActionButton) vistaADevolver.findViewById(R.id.button);
recyclerView = (RecyclerView) vistaADevolver.findViewById(R.id.recyclerViewToDo);
itemList = new ArrayList<>();
results = realm.where(Item.class).equalTo("id", 1).findAll();
final InputMethodManager inputManager = (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
adapterItemsRecycler = new AdapterItemsRecycler(results, getActivity(), new ItemsListener());
recyclerView.setHasFixedSize(true);
recyclerView.addItemDecoration(new SimpleItemDivider(getActivity()));
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity(),LinearLayoutManager.VERTICAL, false));
recyclerView.setAdapter(adapterItemsRecycler);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String itemName = editTxt.getText().toString();
saveIntoDatabase(itemName);
inputManager.hideSoftInputFromWindow(getView().getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
editTxt.getText().clear();
adapterItemsRecycler.notifyDataSetChanged();
}
});
return vistaADevolver;
}
@Override
public void onDestroy() {
super.onDestroy();
realm.close();
}
private void saveIntoDatabase(final String itemName) {
realm.executeTransactionAsync(new Realm.Transaction() {
@Override
public void execute(Realm bgRealm) {
item = bgRealm.createObject(Item.class);
item.setName(itemName);
item.setPoint(itemName);
item.setId(1);
Fragment fragment = new Fragment();
Bundle bundle = new Bundle();
bundle.putString("POINT", item.getPoint());
fragment.setArguments(bundle);
itemList.add(item);
}
}, new Realm.Transaction.OnSuccess() {
@Override
public void onSuccess() {
// Transaction was a success.
Log.v("database", "Stored ok");
}
}, new Realm.Transaction.OnError() {
@Override
public void onError(Throwable error) {
// Transaction failed and was automatically canceled.
Log.e("database", error.getMessage());
}
});
}
class ItemsListener implements AdapterView.OnClickListener{
@Override
public void onClick(View view) {
Item itemTouched = results.get(recyclerView.getChildAdapterPosition(view));
EscuchadorInterface unEscuchador = (EscuchadorInterface)getActivity();
unEscuchador.itemSelected(itemTouched);
}
}
public interface EscuchadorInterface{
public void itemSelected(Item anItem);
}
}
My RecyclerView adapter:
public class AdapterItemsRecycler extends RecyclerView.Adapter {
private RealmResults<Item> itemList;
private Context context;
private View.OnClickListener listener;
private Realm realm;
public AdapterItemsRecycler(RealmResults<Item> itemList, Context context, View.OnClickListener listener) {
this.itemList = itemList;
this.context = context;
this.listener = listener;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, final int viewType) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.my_list_detail, parent, false);
view.setOnClickListener(listener);
ItemViewHolder itemViewHolder = new ItemViewHolder(view);
return itemViewHolder;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
Item item = itemList.get(position);
ItemViewHolder itemViewHolder = (ItemViewHolder) holder;
itemViewHolder.loadItem(item);
}
@Override
public int getItemCount() {
return itemList.size();
}
private class ItemViewHolder extends RecyclerView.ViewHolder{
private TextView itemText;
private ImageButton imageButton;
public ItemViewHolder(View view) {
super(view);
itemText = (TextView) view.findViewById(R.id.textViewItemNameTD);
imageButton = (ImageButton) view.findViewById(R.id.delete);
}
public void loadItem(Item item) {
itemText.setText(item.getName());
imageButton.setImageResource(R.drawable.trash);
}
public ImageButton getImageButton() {
return imageButton;
}
}
}
RecyclerView's detail:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:design="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
tools:context="com.segunfamisa.sample.bottomnav.MainActivity">
<ImageButton
android:id="@+id/delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:tint="#03A9F4"
android:scaleType="centerInside"
android:background="#ffffff"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:onClick="deleteItem"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/textViewItemNameTD"
android:textSize="14dp"
android:textColor="#212121"
android:background="#ffffff"
android:padding="10dp"
android:layout_toRightOf="@+id/delete"/>
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/arrow"
android:scaleType="centerInside"
android:background="#ffffff"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"/>
</RelativeLayout>
回答1:
Just use RealmRecyclerViewAdapter with the RealmResults directly, which handles synchronization between database and list and adapter automatically.
public class FragmentMyList
extends Fragment {
private RecyclerView recyclerView;
private EditText editTxt;
private FloatingActionButton btn;
private AdapterItemsRecycler adapterItemsRecycler;
private Realm realm;
RealmResults<Item> results;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View vistaADevolver = inflater.inflate(R.layout.fragment_my_list, container, false);
getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
Realm.init(getContext());
realm = Realm.getDefaultInstance();
editTxt = (EditText) vistaADevolver.findViewById(R.id.editText);
btn = (FloatingActionButton) vistaADevolver.findViewById(R.id.button);
recyclerView = (RecyclerView) vistaADevolver.findViewById(R.id.recyclerViewToDo);
results = realm.where(Item.class).equalTo("id", 1).findAll();
final InputMethodManager inputManager = (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
adapterItemsRecycler = new AdapterItemsRecycler(results, new ItemsListener());
recyclerView.setHasFixedSize(true);
recyclerView.addItemDecoration(new SimpleItemDivider(getActivity()));
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false));
recyclerView.setAdapter(adapterItemsRecycler);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String itemName = editTxt.getText().toString();
saveIntoDatabase(itemName);
inputManager.hideSoftInputFromWindow(getView().getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
editTxt.getText().clear();
}
});
return vistaADevolver;
}
@Override
public void onDestroy() {
super.onDestroy();
realm.close();
}
private void saveIntoDatabase(final String itemName) {
realm.executeTransactionAsync(new Realm.Transaction() {
@Override
public void execute(Realm bgRealm) {
Item item = bgRealm.createObject(Item.class);
item.setName(itemName);
item.setPoint(itemName);
item.setId(1);
}
}, new Realm.Transaction.OnSuccess() {
@Override
public void onSuccess() {
// Transaction was a success.
Log.v("database", "Stored ok");
}
}, new Realm.Transaction.OnError() {
@Override
public void onError(Throwable error) {
// Transaction failed and was automatically canceled.
Log.e("database", error.getMessage());
}
});
}
class ItemsListener
implements AdapterView.OnClickListener {
@Override
public void onClick(View view) {
Item itemTouched = results.get(recyclerView.getChildAdapterPosition(view));
EscuchadorInterface unEscuchador = (EscuchadorInterface) getActivity();
unEscuchador.itemSelected(itemTouched);
}
}
public interface EscuchadorInterface {
public void itemSelected(Item anItem);
}
}
// compile 'io.realm:android-adapters:2.0.0'
public class AdapterItemsRecycler
extends RealmRecyclerViewAdapter<Item, ItemViewHolder> {
private View.OnClickListener listener;
public AdapterItemsRecycler(OrderedRealmCollection<Item> itemList, View.OnClickListener listener) {
super(itemList, true);
this.listener = listener;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, final int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
View view = inflater.inflate(R.layout.my_list_detail, parent, false);
view.setOnClickListener(listener);
ItemViewHolder itemViewHolder = new ItemViewHolder(view);
return itemViewHolder;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
Item item = getData().get(position);
ItemViewHolder itemViewHolder = (ItemViewHolder) holder;
itemViewHolder.loadItem(item);
}
private static class ItemViewHolder
extends RecyclerView.ViewHolder {
private TextView itemText;
private ImageButton imageButton;
public ItemViewHolder(View view) {
super(view);
itemText = (TextView) view.findViewById(R.id.textViewItemNameTD);
imageButton = (ImageButton) view.findViewById(R.id.delete);
}
public void loadItem(Item item) {
itemText.setText(item.getName());
imageButton.setImageResource(R.drawable.trash);
}
public ImageButton getImageButton() {
return imageButton;
}
}
}
private void deleteFromDatabase(final String itemName) {
realm.executeTransactionAsync(new Realm.Transaction() {
@Override
public void execute(Realm bgRealm) {
Item item = bgRealm.where(Item.class).equalTo("name", itemName).findFirst();
if(item != null) {
item.deleteFromRealm();
}
}
}, new Realm.Transaction.OnSuccess() {
@Override
public void onSuccess() {
// Transaction was a success.
Log.v("database", "Delete ok");
}
}, new Realm.Transaction.OnError() {
@Override
public void onError(Throwable error) {
// Transaction failed and was automatically canceled.
Log.e("database", error.getMessage());
}
});
}
来源：https://stackoverflow.com/questions/42949964/delete-item-from-recyclerview-and-realm-db