我刚刚在项目中使用dbSqlite进行了Login和LoginUp。现在，我正在尝试使用dbSqlite购物车。当我尝试read从数据库中获取数据时，出现此错误：
no such table: cart (code 1): , while compiling: select * from cart
CartFragment.java中的以下代码会导致此错误：
Cursor rs = db.getData();
当我使用DB Browser浏览数据库检查Sqlite时，购物车表不存在。我怎么解决这个问题？该错误是因为表不存在？
DatabaseHelper.java
public class DatabaseHelper extends SQLiteOpenHelper {
public DatabaseHelper(Context context) {
super(context, "Login.db", null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("Create table user(email text primary key, password text)");
db.execSQL("Create table cart(Image text, Title text, Cost text, TotalCost text)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists user");
db.execSQL("drop table if exists cart");
}
public boolean insert (String email, String password){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("email", email);
contentValues.put("password", password);
long ins = db.insert("user", null, contentValues);
if (ins==-1) return false;
else return true;
}
// checking if email exists
public Boolean chkemail(String email){
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("Select * from user where email=?", new String[]{email});
if (cursor.getCount()>0) return false;
else return true;
}
// checking the email and password
public Boolean emailpassword(String email, String password){
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("select * from user where email=? and password=?", new String[]{email,password});
if (cursor.getCount()>0) return true;
else return false;
}
public void AddToCart(String Image, String Title, String Cost, String TotalCost){
SQLiteDatabase db = getWritableDatabase();
ContentValues data = new ContentValues();
data.put("Image",Image);
data.put("Title",Title);
data.put("Cost",Cost);
data.put("TotalCost", TotalCost);
db.insert("cart",null,data);
}
public Cursor getData() {
SQLiteDatabase db = this.getReadableDatabase();
Cursor rs = db.rawQuery( "select * from cart",null);
return rs;
}
}
尝试在此向数据库添加数据。 ProductDetailAdapter.java
public class ProductDetailAdapter extends RecyclerView.Adapter<ProductDetailAdapter.ViewHolder> {
private Context mContext;
private List<Product> productList;
private ImageView imgProductDetail;
private TextView textProductDetailCost, textProductDetailMarket;
private Button btnProductDetail;
private CardView cardViewProductDetail;
DatabaseHelper db;
public ProductDetailAdapter(Context mContext, List<Product> productList) {
this.mContext = mContext;
this.productList = productList;
}
@NonNull
@Override
public ProductDetailAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int i) {
View mView = LayoutInflater.from(parent.getContext()).inflate(R.layout.product_detail_item_view, parent, false);
return new ViewHolder(mView); }
@Override
public void onBindViewHolder(final ProductDetailAdapter.ViewHolder viewHolder, final int position) {
Glide.with(mContext).load(productList.get(position).getProductMarketImage())
.apply(RequestOptions.placeholderOf(R.drawable.ic_glide_img).error(R.drawable.ic_glide_warning)).
into(imgProductDetail);
textProductDetailCost.setText(productList.get(position).getProductCost());
// textProductDetailMarket.setText(productList.get(position).getProductMarket());
cardViewProductDetail.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
btnProductDetail.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
db = new DatabaseHelper(mContext);
String img,cost,title,total;
img = productList.get(position).getProductImage();
cost = productList.get(position).getProductCost();
title = productList.get(position).getProductName();
total = "";
Log.e("img","Image");
Log.e("cost","Cost");
Log.e("title","Title");
db.AddToCart(img,title,cost,total);
Toast.makeText(mContext,"Ürün sepetinize eklendi",Toast.LENGTH_SHORT);
}
});
}
@Override
public int getItemCount() {
return productList.size();
}
class ViewHolder extends RecyclerView.ViewHolder{
ViewHolder(View itemView){
super(itemView);
imgProductDetail = itemView.findViewById(R.id.imageView_product_detail);
textProductDetailCost = itemView.findViewById(R.id.text_product_detail_cost);
// textProductDetailMarket = itemView.findViewById(R.id.textView_product_detail_market);
btnProductDetail = itemView.findViewById(R.id.buttonProductDetail);
cardViewProductDetail = itemView.findViewById(R.id.cardViewProductDetail);
}
}
}
需要在此处从数据库加载数据。 CartFragment.java
public class CartFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private ImageView imageShare;
List<Product> productList;
List<Supermarket> supermarketList;
Product product;
Supermarket supermarket;
DatabaseHelper db;
private Toolbar toolbar;
private RecyclerView recyclerViewCart;
private OnFragmentInteractionListener mListener;
public CartFragment() {
// Required empty public constructor
}
public static CartFragment newInstance(String param1, String param2) {
CartFragment fragment = new CartFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v = inflater.inflate(R.layout.fragment_cart, container, false);
imageShare = v.findViewById(R.id.img_cart_share);
recyclerViewCart = v.findViewById(R.id.recyclerview_cart);
LinearLayoutManager verticalLayoutManager = new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false);
recyclerViewCart.setLayoutManager(verticalLayoutManager);
db = new DatabaseHelper(getContext());
Cursor rs = db.getData();
rs.moveToFirst();
String img = rs.getString(rs.getColumnIndex("Image"));
String title = rs.getString(rs.getColumnIndex("Title"));
String cost = rs.getString(rs.getColumnIndex("Cost"));
}