我正在开发一个Android应用程序，该应用程序显示一系列卡片，其中包含一些存储在本地SQLite数据库中的信息（在主片段中）。
与this问题中的Matteo一样，我已经实现了自定义回收器适配器（GitHub link），还有一个用于滑动的自定义侦听器（SwipeableRecyclerView），但面对的是有点不同的问题。当我刷我的carview项目时，它会回到它的'＆＃39;开始位置，可能根本没有删除以前刷过的项目（来自与我的回收器适配器一起使用的数据库和回收站视图）。
我的数据库助手的代码如下：
public class GeekNotesDatabaseHelper {
static final String DB_NAME = "geeknotes_db";
static final String TABLE = "notes_table";
static final int VERSION = 1;
static final String UID = "_id";
static final String TITLE = "title";
static final String CATEGORY = "category";
private DBHelper dbHelper;
private SQLiteDatabase database;
public GeekNotesDatabaseHelper(Context context) {
dbHelper = new DBHelper(context);
database = dbHelper.getWritableDatabase();
}
public void insertData(String title, String category) {
ContentValues cv = new ContentValues();
cv.put(TITLE, title);
cv.put(CATEGORY, category);
database.insert(TABLE, null, cv);
}
public Cursor getAllData() {
String buildSQL = "SELECT * FROM " + TABLE + " ORDER BY " + UID + " DESC";
return database.rawQuery(buildSQL, null);
}
public void deleteByID(int position) {
database.delete(TABLE, UID + " = " + position, null);
}
private class DBHelper extends SQLiteOpenHelper {
public DBHelper(Context context) {
super(context, DB_NAME, null, VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + TABLE + " (" + UID + " INTEGER " +
"PRIMARY KEY AUTOINCREMENT, " + TITLE + " TEXT, " + CATEGORY + " TEXT);");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE);
onCreate(db);
}
}
}
适配器类：
public class GeekNotesAdapter extends CursorRecyclerAdapter<GeekNotesAdapter.ViewHolder> {
private final Fragment fragment;
private OnItemClickListener itemClickListener;
public GeekNotesAdapter(Cursor cursor, Fragment fragment) {
super(cursor);
this.fragment = fragment;
}
@Override
public void onBindViewHolderCursor(ViewHolder holder, Cursor cursor) {
holder.title.setText(
cursor.getString(cursor.getColumnIndexOrThrow(GeekNotesDatabaseHelper.TITLE)).replaceAll("\\<[^>]*>", ""));
holder.category.setText(
cursor.getString((cursor.getColumnIndexOrThrow(GeekNotesDatabaseHelper.CATEGORY))));
holder.id = cursor.getInt(cursor.getColumnIndexOrThrow(GeekNotesDatabaseHelper.UID));
}
@Override
public GeekNotesAdapter.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
final LayoutInflater mInflater = LayoutInflater.from(viewGroup.getContext());
final View sView = mInflater.inflate(R.layout.note_item, viewGroup, false);
return new ViewHolder(sView);
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
TextView title;
TextView category;
int id;
public ViewHolder(View view) {
super(view);
title = (TextView) view.findViewById(R.id.name);
category = (TextView) view.findViewById(R.id.category);
itemView.setOnClickListener(this);
}
@Override
public void onClick(View v) {
if (itemClickListener != null) {
itemClickListener.onItemClick(v, id);
}
}
}
public interface OnItemClickListener {
public void onItemClick(View view , int position);
}
public void setOnItemClickListener(final OnItemClickListener itemClickListener) {
this.itemClickListener = itemClickListener;
}
}
我的Fragment代码包含cardview-items：
public class GeekNotesFragment extends Fragment {
GeekNotesDatabaseHelper dbHelper;
GeekNotesAdapter adapter;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.main_fragment, container, false);
dbHelper = new GeekNotesDatabaseHelper(getActivity());
Bundle bundle = getArguments();
if (bundle != null) {
// String itemTitle = bundle.getString("tag_item_title");
// String itemCategory = bundle.getString("tag_item_category");
Item item = (Item) bundle.getSerializable("note_item");
dbHelper.insertData(item.getName(), item.getCategory());
}
final RecyclerView recyclerList = (RecyclerView) v.findViewById(R.id.itemsInCards);
recyclerList.setHasFixedSize(true);
LinearLayoutManager llm = new LinearLayoutManager(getActivity());
llm.setOrientation(LinearLayoutManager.VERTICAL);
recyclerList.setLayoutManager(llm);
setTargetFragment(GeekNotesFragment.this, 0);
adapter = new GeekNotesAdapter(dbHelper.getAllData(), getTargetFragment());
recyclerList.setAdapter(adapter);
SwipeableRecyclerViewTouchListener swipeTouchListener =
new SwipeableRecyclerViewTouchListener(recyclerList, new SwipeableRecyclerViewTouchListener.SwipeListener() {
@Override
public boolean canSwipe(int position) {
return true;
}
@Override
public void onDismissedBySwipeLeft(RecyclerView recyclerView, int[] reverseSortedPositions) {
for (int position : reverseSortedPositions) {
dbHelper.deleteByID(position);
adapter.notifyItemRemoved(position);
}
adapter.notifyDataSetChanged();
}
@Override
public void onDismissedBySwipeRight(RecyclerView recyclerView, int[] reverseSortedPositions) {
for (int position : reverseSortedPositions) {
dbHelper.deleteByID(position);
adapter.notifyItemRemoved(position);
}
adapter.notifyDataSetChanged();
}
});
recyclerList.addOnItemTouchListener(swipeTouchListener);
FloatingActionButton fab = (FloatingActionButton) v.findViewById(R.id.fab);
fab.attachToRecyclerView(recyclerList);
// fab.setBaselineAlignBottom(true);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.container, new NewNoteFragment());
ft.addToBackStack(null);
ft.commit();
}
});
return v;
}
}
将项目添加到我的数据库/ recyclerview很好。但删除 - 不幸的是，并没有。我是开发Android应用程序的新手，所以，请告诉我这里可能有什么问题，哪个问题不允许我正确删除卡片项目＆amp;如何解决？
提前致谢。
答案 0 :(得分：0)
嗯，这是一个很老的帖子。但我想回答，因为它可以帮助别人。
答案 - 尝试使用回收器视图的方法，例如 -
获取该位置的视图持有者，然后访问该视图的值，以便在数据库中删除。