我是android编程的新手，我在从firestore显示数据时遇到了问题。我想在导航抽屉中以片段形式显示数据。我找到了在活动中显示它的教程，但没有任何碎片。请帮帮我。
public class MainActivity extends AppCompatActivity {
Toolbar toolbar;
DrawerLayout drawerLayout;
ActionBarDrawerToggle actionBarDrawerToggle;
NavigationView navigationView;
FragmentTransaction fragmentTransaction;
private boolean shouldLoadProductFragOnBackPress = false;
public static int navItemIndex = 0;
public FirebaseAuth mAuth;
FirebaseFirestore db = FirebaseFirestore.getInstance();
private void Load_Product_fragment() {
navItemIndex = 0;
fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.maincontainer,new ProductFragment());
fragmentTransaction.commit();
getSupportActionBar().setTitle(R.string.Productfragment_Title);
drawerLayout.closeDrawers();
}
private void Load_Service_fragment(){
navItemIndex = 1;
fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.maincontainer,new ServiceFragment());
fragmentTransaction.commit();
getSupportActionBar().setTitle(R.string.Servicefragmnet_Title);
drawerLayout.closeDrawers();
shouldLoadProductFragOnBackPress = true;
}
private void Load_Account_fragment(){
navItemIndex = 2;
fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.maincontainer,new AccountFragment());
fragmentTransaction.commit();
getSupportActionBar().setTitle(R.string.Accountfragment_Title);
drawerLayout.closeDrawers();
shouldLoadProductFragOnBackPress = true;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar=(Toolbar)findViewById(R.id.Toolbar_Layout);
setSupportActionBar(toolbar);
drawerLayout=(DrawerLayout) findViewById(R.id.Drawer_Layout);
actionBarDrawerToggle = new ActionBarDrawerToggle(this,drawerLayout,toolbar,R.string.drawer_open,R.string.drawer_close);
drawerLayout.addDrawerListener(actionBarDrawerToggle);
drawerLayout.openDrawer(Gravity.LEFT);
Load_Product_fragment();
navigationView= findViewById(R.id.Navigation_View);
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId())
{
case R.id.Productsfragment_ND:
Load_Product_fragment();
item.setChecked(true);
break;
case R.id.Servicefragment_ND:
Load_Service_fragment();
item.setChecked(true);
break;
case R.id.Accountfragemnt_ND:
Load_Account_fragment();
item.setChecked(true);
break;
}
return false;
}
});
}
@Override
public void onBackPressed() {
if (drawerLayout.isDrawerOpen(GravityCompat.START)) {
drawerLayout.closeDrawers();
return;
}
// This code loads home fragment when back key is pressed
// when user is in other fragment than home
if (shouldLoadProductFragOnBackPress) {
// checking if user is on other navigation menu
// rather than home
if (navItemIndex !=0) {
navItemIndex = 0;
shouldLoadProductFragOnBackPress = false;
Load_Product_fragment();
return;
}
}
super.onBackPressed();
}
@Override
protected void onPostCreate(@Nullable Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
actionBarDrawerToggle.syncState();
}
public void del(View view) {db.collection("products").document("test")
.delete()
.addOnSuccessListener(new OnSuccessListener<Void>() {
@Override
public void onSuccess(Void aVoid) {
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
}
});
}
}
这是我的主要活动。它包含3个片段的导航抽屉的要求。我有一个链接到应用程序的Firestore数据库。我需要在这些片段中显示数据库的内容。
我不确定这是否是正确的方法。请帮助我
public class ProductFragment extends Fragment {
private static final String TAG = ProductFragment.class.getSimpleName();
private RecyclerView recipeRecyclerview;
private LinearLayoutManager linearLayoutManager;
private Product_adapter mAdapter;
private DatabaseReference mDatabaseRef;
private DatabaseReference childRef;
public ProductFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate (R.layout.fragment_product, container, false);
getActivity().setTitle(getString(R.string.Productfrag_title));
linearLayoutManager = new LinearLayoutManager(getActivity());
recipeRecyclerview = view.findViewById(R.id.List_recycleview);
recipeRecyclerview.setHasFixedSize(true);
mDatabaseRef = FirebaseDatabase.getInstance().getReference();
childRef = mDatabaseRef.child("recipes");
mAdapter = new Product_adapter(Product_response.class, R.layout.list_layout, View_holder.class, childRef, getContext());
recipeRecyclerview.setLayoutManager(linearLayoutManager);
recipeRecyclerview.setAdapter(mAdapter);
return view;
} } 这是我的产品片段。我试图添加回收站视图。
适配器
public class Product_adapter extends RecyclerView.Adapter {
FirebaseFirestore db = FirebaseFirestore.getInstance();
private Context context;
Query query = db.collection("products");
FirestoreRecyclerOptions<Product_response> response = new FirestoreRecyclerOptions.Builder<Product_response>()
.setQuery(query, Product_response.class)
.build();
FirestoreRecyclerAdapter adapter = new FirestoreRecyclerAdapter<Product_response, View_holder>(response) {
@Override
protected void onBindViewHolder(View_holder holder, int position, Product_response model) {
}
@Override
public View_holder onCreateViewHolder(ViewGroup group, int i) {
// Create a new instance of the ViewHolder, in this case we are using a custom
// layout called R.layout.message for each item
View view = LayoutInflater.from(group.getContext())
.inflate(R.layout.list_layout, group, false);
return new View_holder(view);
}
};
public Product_adapter(Class<Product_response> product_responseClass, int list_layout, Class<View_holder> view_holderClass, DatabaseReference childRef, Context context) {
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return null;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
}
@Override
public int getItemCount() {
return 0;
}
}
查看持有人
public class View_holder extends RecyclerView.ViewHolder{
private static final String TAG = View_holder.class.getSimpleName();
public TextView main_text, subtext ;
public ImageView image;
public View_holder(View itemView) {
super(itemView);
main_text = (TextView)itemView.findViewById(R.id.List_maintext);
subtext = (TextView)itemView.findViewById(R.id.List_subtext);
image = (ImageView)itemView.findViewById(R.id.List_imageview);
}
}
接下来我将显示响应页面，其中我使用了firebase的getter和setter
import com.google.firebase.firestore.IgnoreExtraProperties;
@IgnoreExtraProperties
public class Product_response {
private String Product;
private String Cost;
public Product_response() {
}
public Product_response(String Product, String Cost){
this.Product= Product;
this.Cost= Cost;
}
public String getProduct() {
return Product;
}
public void setProduct(String Product) {
this.Product = Product;
}
public String getCost(){
return Cost;
}
public void setCost(String Cost)
{
this.Cost = Cost;
}
}
This is how my database looks like. I need to display this products in my fragment
This is the github link of the app. Please help me complete this
