如何将firebase添加到android studio中的片段

Question

我正在制作一个 android 电子商务应用程序，我下载了一个应用程序模板，但在该模板中，片段中没有 firebase，我希望当用户单击结帐按钮时，他选择的产品应该进入 firebase 数据库，但所有视频我看到他们使用活动。所以请帮助我。 CartFragment.java

 package com.example.shoppingcart.views;
    
    import android.content.Intent;
    import android.os.Bundle;
    
    
    
    import androidx.annotation.NonNull;
    import androidx.annotation.Nullable;
    import androidx.fragment.app.Fragment;
    import androidx.lifecycle.Observer;
    import androidx.lifecycle.ViewModelProvider;
    import androidx.navigation.NavController;
    import androidx.navigation.Navigation;
    import androidx.recyclerview.widget.DividerItemDecoration;
    import androidx.recyclerview.widget.RecyclerView;
    
    import android.text.TextUtils;
    import android.util.Log;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.ImageView;
    import android.widget.RadioButton;
    import android.widget.Spinner;
    import android.widget.TextView;
    import android.widget.Toast;
    import android.widget.Toolbar;
    
    import com.example.shoppingcart.R;
    import com.example.shoppingcart.adapters.CartListAdapter;
    import com.example.shoppingcart.cartholder;
    import com.example.shoppingcart.databinding.FragmentCartBinding;
    import com.example.shoppingcart.dataholder;
    import com.example.shoppingcart.models.CartItem;
    import com.example.shoppingcart.productholder;
    import com.example.shoppingcart.viewmodels.ShopViewModel;
    import com.google.firebase.auth.FirebaseAuth;
    import com.google.firebase.database.DatabaseReference;
    import com.google.firebase.database.FirebaseDatabase;
    import com.google.firebase.firestore.FirebaseFirestore;
    
    import java.text.SimpleDateFormat;
    import java.util.Calendar;
    import java.util.HashMap;
    import java.util.List;
    import java.util.UUID;
    
    public class CartFragment extends Fragment implements CartListAdapter.CartInterface {
    
        private static final String TAG = "CartFragment";
        private ImageView productImage;
        private TextView productname;
        private TextView productprice;
        private TextView productcategory;
        private Spinner productquantity;
        UUID uuid = UUID.randomUUID();
        String randomUUID = uuid.toString().trim();
        ShopViewModel shopViewModel;
        FragmentCartBinding fragmentCartBinding;
        NavController navController;
        Button button;
    
        private void finishActivity() {
            if (getActivity() != null) {
                getActivity().finish();
            }
        }
    
        public CartFragment() {
            // Required empty public constructor
        }
    
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            // Inflate the layout for this fragment
            fragmentCartBinding = FragmentCartBinding.inflate(inflater, container, false);
            return fragmentCartBinding.getRoot();
    
    
        }
    
        @Override
        public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);
            
    
            navController = Navigation.findNavController(view);
    
            final CartListAdapter cartListAdapter = new CartListAdapter(this);
            fragmentCartBinding.cartRecyclerView.setAdapter(cartListAdapter);
            fragmentCartBinding.cartRecyclerView.addItemDecoration(new DividerItemDecoration(requireContext(), DividerItemDecoration.VERTICAL));
    
            shopViewModel = new ViewModelProvider(requireActivity()).get(ShopViewModel.class);
            shopViewModel.getCart().observe(getViewLifecycleOwner(), new Observer<List<CartItem>>() {
                @Override
                public void onChanged(List<CartItem> cartItems) {
                    cartListAdapter.submitList(cartItems);
                    fragmentCartBinding.placeOrderButton.setEnabled(cartItems.size() > 0);
                }
            });
    
            shopViewModel.getTotalPrice().observe(getViewLifecycleOwner(), new Observer<Double>() {
                @Override
                public void onChanged(Double aDouble) {
                    fragmentCartBinding.orderTotalTextView.setText("Total: PKR " + aDouble.toString());
    
    
                }
            });
    
            button = (Button) getView().findViewById(R.id.placeOrderButton);
            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Intent intent = new Intent(CartFragment.this.getActivity(), CheckoutActivity.class);
                    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
                    startActivity(intent);
                    finishActivity();
                }
            });
        }
    
        @Override
        public void deleteItem(CartItem cartItem) {
            shopViewModel.removeItemFromCart(cartItem);
        }
    
        @Override
        public void changeQuantity(CartItem cartItem, int quantity) {
            shopViewModel.changeQuantity(cartItem, quantity);
        }
    
    
    
        }

fragment_cart.xml

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:orientation="vertical"
        tools:context=".views.CartFragment"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/cartRecyclerView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
            tools:listitem="@layout/cart_row"
            tools:itemCount="2"
            />

        <Space
            android:layout_width="match_parent"
            android:layout_height="16dp" />

        <TextView
            android:id="@+id/orderTotalTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="end"
            android:layout_margin="8dp"
            android:text="Total: PKR 26"
            android:textAppearance="@style/TextAppearance.MaterialComponents.Headline6" />

        <Button
            android:id="@+id/placeOrderButton"
            style="@style/Widget.MaterialComponents.Button.UnelevatedButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="end"
            android:layout_margin="8dp"
            android:text="Proceed To Checkout"
            android:textAppearance="@style/TextAppearance.MaterialComponents.Caption" />

    </LinearLayout>
</ScrollView>

Answer 1

您必须使用哪种 firebase 数据库，因为这两种方法都相似... 活动和片段方法相同，方法没有任何变化...

我将向您展示 firestore 方法，因为我不知道您必须使用哪一种

在片段中首先初始化

FirebaseFirestore firebaseFirestore;

oncreateview 初始化

firebaseFirestore = FirebaseFirestore.getInstance(); 

在你可以执行所有的 crud 操作之后，除了前两行之外的所有东西都是必需的

简单的使用兄弟...