Question

我正在开发一个食谱书应用程序。我的数据结构如下：

 Reference
   - users
     -53
     -movies
       -id1
          (-name
          -rating
          -ingredients(list)
          -recipe
          -photo)
       -id2 (....)

正确添加数据，但当我使用以下代码进行检索时，应用程序会停止。我的模型类是 Recipe 。

我需要创建一个网格结构来显示所有菜肴。我认为这段代码应该用于此目的，但它并没有。我做错了什么？

当用户点击特定菜肴时，应显示该菜肴的配方和其他详细信息。如何在火力基地进行这种选择性检索？

package foodelicious.com.foodfinal;

public class MainActivity extends AppCompatActivity {

private FloatingActionButton fab;

ScaleAnimation shrinkAnim;
private RecyclerView mRecyclerView;
private StaggeredGridLayoutManager mLayoutManager;
private TextView tvNoRecipes;

private ImageView DPoster;
private TextView  DMovieName,DIngredients,DRecipeTitle,DRecipe;
private RatingBar Drate;


//Getting reference to Firebase Database
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference mDatabaseReference = database.getReference();

private static final String userId = "53";


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //Initializing our Recyclerview
    mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
    tvNoRecipes = (TextView) findViewById(R.id.tv_no_recipes);

    DPoster=(ImageView) findViewById(R.id.Dposter);
    DIngredients=(TextView) findViewById(R.id.Ding);
    //scale animation to shrink floating actionbar
    shrinkAnim = new ScaleAnimation(1.15f, 0f, 1.15f, 0f, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);

    if (mRecyclerView != null) {
        //to enable optimization of recyclerview
        mRecyclerView.setHasFixedSize(true);
    }
    //using staggered grid pattern in recyclerview
    mLayoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);
    mRecyclerView.setLayoutManager(mLayoutManager);

    //Say Hello to our new FirebaseUI android Element, i.e., FirebaseRecyclerAdapter
    FirebaseRecyclerAdapter<Recipe,RecipeViewHolder> adapter = new FirebaseRecyclerAdapter<Recipe, RecipeViewHolder>(
            Recipe.class,
            R.layout.recipe_board_item,
            RecipeViewHolder.class,
            //referencing the node where we want the database to store the data from our Object
            mDatabaseReference.child("users").child(userId).child("movies").getRef()
    ) {
        @Override
        protected void populateViewHolder(final RecipeViewHolder viewHolder, Recipe model, int position) {
            if(tvNoRecipes.getVisibility()== View.VISIBLE){
                tvNoRecipes.setVisibility(View.GONE);

            }
            viewHolder.tvRecipeName.setText(model.getRecipeName());
            viewHolder.ratingBar.setRating(model.getRecipeRating());
            Picasso.with(MainActivity.this).load(model.getRecipePoster()).into(viewHolder.ivRecipePoster);

            viewHolder.ivRecipePoster.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View view) {

                    setContentView(R.layout.recipe_details);

                }
            });
        }
    };

    mRecyclerView.setAdapter(adapter);


    fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            getSupportFragmentManager().beginTransaction()
                    .replace(R.id.frame_container, new AddRecipeFragment())
                    .addToBackStack(null)
                    .commit();
            //animation being used to make floating actionbar disappear
            shrinkAnim.setDuration(400);
            fab.setAnimation(shrinkAnim);
            shrinkAnim.start();
            shrinkAnim.setAnimationListener(new Animation.AnimationListener() {
                @Override
                public void onAnimationStart(Animation animation) {

                }

                @Override
                public void onAnimationEnd(Animation animation) {
                    //changing floating actionbar visibility to gone on animation end
                    fab.setVisibility(View.GONE);
                }

                @Override
                public void onAnimationRepeat(Animation animation) {


                }
            });

        }
    });


}


@Override
public void onBackPressed() {
    super.onBackPressed();
    if (fab.getVisibility() == View.GONE)
        fab.setVisibility(View.VISIBLE);
}



//ViewHolder for our Firebase UI
public static class RecipeViewHolder extends RecyclerView.ViewHolder{

    TextView tvRecipeName;
    RatingBar ratingBar;
    ImageView ivRecipePoster;

    public RecipeViewHolder(View v) {
        super(v);
        tvRecipeName = (TextView) v.findViewById(R.id.iv_dish_name);
        ratingBar = (RatingBar) v.findViewById(R.id.rating_bar);
        ivRecipePoster = (ImageView) v.findViewById(R.id.iv_dish_poster);

    }
}
}

logcat的

10-05 16：43：08.462 30349-30479 / foodelicious.com.foodfinal D / FA：连接到远程服务 10-05 16：43：08.463 30349-30479 / foodelicious.com.foodfinal V / FA：处理排队的服务任务：1 10-05 16：43：13.592 30349-30479 / foodelicious.com.foodfinal V / FA：不活动，断开与服务的连接 10-05 16：43：21.549 30349-30354 / foodelicious.com.foodfinal I / art：部分代码缓存集合，代码= 29KB，数据= 29KB 10-05 16：43：21.550 30349-30354 / foodelicious.com.foodfinal I / art：代码缓存收集后，代码= 29KB，数据= 29KB 10-05 16：43：21.550 30349-30354 / foodelicious.com.foodfinal I / art：将代码缓存容量增加到128KB 10-05 16：43：21.617 30349-30349 / foodelicious.com.foodfinal D / AndroidRuntime：关闭VM 10-05 16：43：21.625 30349-30349 / foodelicious.com.foodfinal E / AndroidRuntime：FATAL EXCEPTION：main 流程：foodelicious.com.foodfinal，PID：30349 com.google.firebase.database.DatabaseException：类foodelicious.com.foodfinal.models.Recipe缺少一个没有参数的构造函数在com.google.android.gms.internal.zzbqi $ zza.zze（未知来源）在com.google.android.gms.internal.zzbqi $ zza.zzaG（未知来源）在com.google.android.gms.internal.zzbqi.zze（未知来源）在com.google.android.gms.internal.zzbqi.zzb（未知来源）在com.google.android.gms.internal.zzbqi.zza（未知来源）在com.google.firebase.database.DataSnapshot.getValue（未知来源）在com.firebase.ui.database.FirebaseRecyclerAdapter.parseSnapshot（FirebaseRecyclerAdapter.java:147）在com.firebase.ui.database.FirebaseRecyclerAdapter.getItem（FirebaseRecyclerAdapter.java:136）在com.firebase.ui.database.FirebaseRecyclerAdapter.onBindViewHolder（FirebaseRecyclerAdapter.java:176）在android.support.v7.widget.RecyclerView $ Adapter.onBindViewHolder（RecyclerView.java:6476）在android.support.v7.widget.RecyclerView $ Adapter.bindViewHolder（RecyclerView.java:6509）在android.support.v7.widget.RecyclerView $ Recycler.tryBindViewHolderByDeadline（RecyclerView.java:5452）在android.support.v7.widget.RecyclerView $ Recycler.tryGetViewHolderForPositionByDeadline（RecyclerView.java:5718）在android.support.v7.widget.RecyclerView $ Recycler.getViewForPosition（RecyclerView.java:5557）在android.support.v7.widget.RecyclerView $ Recycler.getViewForPosition（RecyclerView.java:5553）在android.support.v7.widget.LayoutState.next（LayoutState.java:100）在android.support.v7.widget.StaggeredGridLayoutManager.fill（StaggeredGridLayoutManager.java:1570）在android.support.v7.widget.StaggeredGridLayoutManager.onLayoutChildren（StaggeredGridLayoutManager.java:682）在android.support.v7.widget.StaggeredGridLayoutManager.onLayoutChildren（StaggeredGridLayoutManager.java:604）在android.support.v7.widget.RecyclerView.dispatchLayoutStep2（RecyclerView.java:3693）在android.support.v7.widget.RecyclerView.dispatchLayout（RecyclerView.java:3410）在android.support.v7.widget.RecyclerView.consumePendingUpdateOperations（RecyclerView.java:1710）在android.support.v7.widget.RecyclerView $ 1.run（RecyclerView.java:346）在android.view.Choreographer $ CallbackRecord.run（Choreographer.java:871）在android.view.Choreographer.doCallbacks（Choreographer.java:683）在android.view.Choreographer.doFrame（Choreographer.java:616）在android.view.Choreographer $ FrameDisplayEventReceiver.run（Choreographer.java:857）在android.os.Handler.handleCallback（Handler.java:751）在android.os.Handler.dispatchMessage（Handler.java:95）在android.os.Looper.loop（Looper.java:154）在android.app.ActivityThread.main（ActivityThread.java:6123） at java.lang.reflect.Method.invoke（Native Method）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:867）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:757）

Answer 1

错误：

com.google.firebase.database.DatabaseException：class foodelicious.com.foodfinal.models.Recipe缺少一个没有参数的构造函数

<强>解决方案：将默认（无参数）构造函数添加到类Recipe

public class Recipe ... { public Recipe() { // } }

当我尝试将数据从firebase数据库添加到firebaseViewHolder

logcat的

1 个答案: