如何解决如何获得总计的片段
请帮助我，我正面临这些问题，并且花了更多时间来解决这些问题，但是他们打电话给多友陪伴，所以请显示视频并建议我找出并解决问题。它是一个简单的杂货店应用程序为了帮助检查我的知识，请提供帮助并有可能分享另一种快速获得我解决方案的快速方法...感谢社区的支持..
i want similer to these in fragmnet
我的购物车片段代码
public class CartFragment extends Fragment implements UpdateInf{
RecyclerView cartList;
// public static List<ProductModel> cartModels;
private List<ProductModel> cartItemList;
public static TextView tvTotalWithCheckout;
CartHelper cartHelper;
public static double grandTotalPlus = 0.0d;
int cartCount;
ProductModel productModel;
UpdateInf updateInf;
public CartFragment() {
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater,@Nullable ViewGroup container,@Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_cart,container,false);
cartList = view.findViewById(R.id.cartList);
tvTotalWithCheckout = view.findViewById(R.id.tvTotalWithCheckout);
cartHelper = new CartHelper(getActivity());
productModel = new ProductModel();
updateInf = this;
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
cartList.setLayoutManager(linearLayoutManager);
//LayoutAnimationController layoutAnimationController = AnimationUtils.loadLayoutAnimation(getActivity(),R.anim.layout_anim_right_to_left);
// cartList.getAdapter().notifyDataSetChanged();
// cartList.setLayoutAnimation(layoutAnimationController);
//cartList.scheduleLayoutAnimation();
DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(getActivity(),DividerItemDecoration.VERTICAL);
cartList.addItemDecoration(dividerItemDecoration);
cartItemList = cartHelper.getAllProducts();
MyCartAdapter myCartAdapter = new MyCartAdapter(getActivity(),cartItemList,updateInf);
cartList.setAdapter(myCartAdapter);
// tvTotalWithCheckout.setText( "\u20B9" + grandTotal(cartItemList));
Log.e("grandCheckTotal","setMyCartItem: "+grandTotalPlus);
tvTotalWithCheckout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getActivity(),CheckoutActivity.class);
startActivity(intent);
}
});
return view;
}
@Override
public void setQuantity(int quantity) {
grandTotal(cartItemList);
Log.e("grandTotal","setQuantity: "+ grandTotalPlus);
}
private double grandTotal(List<ProductModel> cartItemList) {
for (ProductModel model : cartItemList) {
// Log.e("cartData","setMyCartItem: " + model.getProductId() + ":" + model.getProductName());
cartCount = model.getProductQty();
grandTotalPlus += Double.parseDouble(model.getProductPrice()) * cartCount;
}
return grandTotalPlus;
}
}
**my adapter code**
public class MyCartAdapter extends RecyclerView.Adapter<MyCartAdapter.Holder> {
private Context context;
private List<ProductModel> productModels;
CartHelper cartHelper;
ProductModel productModel;
UpdateInf updateInf;
public MyCartAdapter(Context context,List<ProductModel> productModels,UpdateInf updateInf) {
this.context = context;
this.productModels = productModels;
cartHelper = new CartHelper(context);
this.updateInf = updateInf;
}
@NonNull
@Override
public Holder onCreateViewHolder(@NonNull ViewGroup parent,int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_cart_items,parent,false);
return new Holder(view);
}
@Override
public void onBindViewHolder(@NonNull final Holder holder,final int position) {
productModel = productModels.get(position);
Glide.with(context).load(productModels.get(position).getProductImage()).into(holder.cartImgProduct);
holder.tvProductName.setText(productModels.get(position).getProductName());
holder.tvProductPrice.setText("\u20B9" + productModels.get(position).getProductPrice());
holder.tvProductType.setText(productModels.get(position).getProductType());
holder.tvQty.setText(String.valueOf(productModels.get(position).getProductQty()));
holder.imgIncrement.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//grandTotalPlus = 0.0d;
int cartIncrementItem = productModels.get(position).getProductQty();
cartIncrementItem += 1;
productModels.get(position).setProductQty(cartIncrementItem);
// double cash = Double.parseDouble(productModels.get(position).getProductPrice()) * productModels.get(position).getProductQty();
holder.tvQty.setText(String.valueOf(productModels.get(position).getProductQty()));
// productModels.get(position).setTotalCash(cash);
cartHelper.updateCart(new ProductModel(productModels.get(position).getProductId(),productModels.get(position).getProductQty()));
updateInf.setQuantity(cartIncrementItem);
}
});
holder.imgDecrement.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int cartDecrementItem = productModels.get(position).getProductQty();
if (cartDecrementItem == 1) {
} else {
cartDecrementItem -= 1;
productModels.get(position).setProductQty(cartDecrementItem);
holder.tvQty.setText(String.valueOf(productModels.get(position).getProductQty()));
updateInf.setQuantity(cartDecrementItem);
}
cartHelper.updateCart(new ProductModel(productModels.get(position).getProductId(),productModels.get(position).getProductQty()));
}
});
}
@Override
public int getItemCount() {
return productModels.size();
}
class Holder extends RecyclerView.ViewHolder {
ImageView cartImgProduct,imgRemoveCart,imgIncrement,imgDecrement;
TextView tvProductName,tvProductPrice,tvProductType,tvQty;
public Holder(@NonNull View itemView) {
super(itemView);
cartImgProduct = itemView.findViewById(R.id.cartImgProduct);
tvProductName = itemView.findViewById(R.id.tvProductName);
tvProductPrice = itemView.findViewById(R.id.tvProductPrice);
tvProductType = itemView.findViewById(R.id.tvProductType);
imgIncrement = itemView.findViewById(R.id.imgIncrement);
imgDecrement = itemView.findViewById(R.id.imgDecrement);
tvQty = itemView.findViewById(R.id.tvQty);
}
}
}
我的购物车帮助代码
public class CartHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "grocery_store";
private static final String TABLE_CART = "cart";
private static final String KEY_PRODUCT_ID = "product_id";
private static final String KEY_PRODUCT_NAME = "product_name";
private static final String KEY_PRODUCT_PRICE = "product_price";
private static final String KEY_PRODUCT_TYPE = "product_type";
private static final String KEY_PRODUCT_IMAGE = "product_image";
private static final String KEY_PRODUCT_QTY = "product_qty";
private static final String KEY_TOTAL_CASH = "total_cash";
public CartHelper(Context context) {
super(context,DATABASE_NAME,null,DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_CART_TABLE =
"CREATE TABLE " + TABLE_CART + "(" + KEY_PRODUCT_ID + " TEXT PRIMARY KEY,"
+ KEY_PRODUCT_NAME + " TEXT,"
+ KEY_PRODUCT_PRICE + " TEXT,"
+ KEY_PRODUCT_TYPE + " TEXT,"
+ KEY_PRODUCT_IMAGE + " TEXT,"
+ KEY_PRODUCT_QTY + " INTEGER" + ")";
db.execSQL(CREATE_CART_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_CART);
onCreate(db);
}
public void addToCart(ProductModel productModels) {
SQLiteDatabase sqLiteDatabase = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(KEY_PRODUCT_ID,productModels.getProductId());
contentValues.put(KEY_PRODUCT_NAME,productModels.getProductName());
contentValues.put(KEY_PRODUCT_PRICE,productModels.getProductPrice());
contentValues.put(KEY_PRODUCT_TYPE,productModels.getProductType());
contentValues.put(KEY_PRODUCT_IMAGE,productModels.getProductImage());
contentValues.put(KEY_PRODUCT_QTY,productModels.getProductQty());
sqLiteDatabase.insert(TABLE_CART,contentValues);
sqLiteDatabase.close();
}
public List<ProductModel> getAllProducts() {
List<ProductModel> productModelList = new ArrayList<ProductModel>();
String query = "SELECT * FROM " + TABLE_CART;
SQLiteDatabase sqLiteDatabase = this.getWritableDatabase();
Cursor cursor = sqLiteDatabase.rawQuery(query,null);
if (cursor.moveToFirst()) {
do {
ProductModel productModel = new ProductModel();
productModel.setProductId(cursor.getString(0));
productModel.setProductName(cursor.getString(1));
productModel.setProductPrice(cursor.getString(2));
productModel.setProductType(cursor.getString(3));
productModel.setProductImage(cursor.getString(4));
productModel.setProductQty(cursor.getInt(5));
productModelList.add(productModel);
} while (cursor.moveToNext());
}
return productModelList;
}
public int updateCart(ProductModel productModel) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_PRODUCT_QTY,productModel.getProductQty());
//values.put(KEY_TOTAL_CASH,productModel.getTotalCash());
//values.put(KEY_PRODUCT_PRICE,productModel.getProductPrice());
// updating row
return db.update(TABLE_CART,values,KEY_PRODUCT_ID + " = ? ",new String[]{String.valueOf(productModel.getProductId())});
}
// Deleting single contact
public void deleteCart(ProductModel productModel) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_CART,KEY_PRODUCT_ID + " = ?",new String[]{String.valueOf(productModel.getProductId())});
db.close();
}
}
解决方法
private double grandTotal(List<ProductModel> cartItemList) {
grandTotalPlus = 0.0d // Reinitialze to zero
for (ProductModel model : cartItemList) {
// Log.e("cartData","setMyCartItem: " + model.getProductId() + ":" + model.getProductName());
cartCount = model.getProductQty();
grandTotalPlus += Double.parseDouble(model.getProductPrice()) * cartCount;
}
return grandTotalPlus;
}
grandtotalplus是一个静态变量，当您离开页面时，它的值永远不会重置，因此，第一次访问购物车页面时，它的值是50。之后，当您返回并添加更多商品，然后返回购物车页面时，它仍然具有值50，您便开始添加它。这就是为什么你要135。
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