尝试在 Android 中的空对象引用错误上调用虚拟方法“void android.widget.TextView.setText(java.lang.CharSequence)”

Question

我在其他问题上得到了帮助，试图解决这个问题，但仍然没有运气，只是继续获得相同的空对象引用。

我已经包含了这个问题的相关文件，只是无法解决这个问题。 任何建议都非常受欢迎。

食谱类

    public class Recipe extends MainActivity {

    TabLayout tabLayout;
    ImageView recipeImage;
    TextView descriptionText, courseText, servingsText, costText, caloriesText, methodText;
    RecyclerView listIngredient;
    SQLiteDatabase db;
    String search_name;
    Cursor c;
    RecyclerViewAdapter adapterRecipe;
    List<RecipeList> itemRecipe = new ArrayList<>();

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.recipe);
        //search_name = getIntent().getStringExtra("NAME");
        search_name = "Speedy chicken couscous";

        loadRecipe();
        //recyclerview Recipe
        adapterRecipe = new RecyclerViewAdapter(this, itemRecipe);
        listIngredient = findViewById(R.id.listIngredient);

        RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(this,
                LinearLayoutManager.VERTICAL, false);
        listIngredient.setLayoutManager(mLayoutManager);
        listIngredient.setItemAnimator(new DefaultItemAnimator());
        listIngredient.setAdapter(adapterRecipe);

    }
    public void loadRecipe() {
        itemRecipe.clear();
        db = (new DatabaseManager(this).getWritableDatabase());
        String RECIPE_SEARCH = " SELECT A.recipe, A.ingredient_quantity, B.measurement_name, B.ingredient_name, B.description " +
                "FROM " + DatabaseManager.TABLE_QUANTITY + " AS A JOIN " + DatabaseManager.TABLE_INGREDIENTS +
                " AS B ON A.ingredient = B.ingredient_name";
        String selectQuery = "";
        selectQuery = RECIPE_SEARCH + " WHERE A.recipe LIKE ?";
        c = db.rawQuery(selectQuery, new String[]{"%" + search_name + "%"});
        if (c.moveToFirst()) {
            do {
                RecipeList recipeList = new RecipeList();
                recipeList.setRecipe(c.getString(c.getColumnIndex("recipe")));
                recipeList.setIngredient_amount(c.getString(c.getColumnIndex("ingredient_quantity")));
                recipeList.setMeasurement_name(c.getString(c.getColumnIndex("measurement_name")));
                recipeList.setIngredient_name(c.getString(c.getColumnIndex("ingredient_name")));
                recipeList.setDescription(c.getString(c.getColumnIndex("description")));
                itemRecipe.add(recipeList);
            } while (c.moveToNext());
            c.close();
        }

    }
}

回收器适配器

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {

    private List<RecipeList> itemRecipe;
    private LayoutInflater mInflater;
    private ItemClickListener mClickListener;

    // data is passed into the constructor
    RecyclerViewAdapter(Context context, List<RecipeList> data) {
        this.mInflater = LayoutInflater.from(context);
        this.itemRecipe = data;
    }

    // inflates the row layout from xml when needed
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = mInflater.inflate(R.layout.fragment_item, parent, false);
        return new ViewHolder(view);
    }

    // binds the data to the TextView in each row
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        holder.myTextView.setText(itemRecipe.get(position).toString());

    }

    // total number of rows
    @Override
    public int getItemCount() {
        return itemRecipe.size();
    }


    // stores and recycles views as they are scrolled off screen
    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        TextView myTextView;

        ViewHolder(View itemView) {
            super(itemView);
            myTextView = itemView.findViewById(R.id.listIngredient);
            itemView.setOnClickListener(this);
        }

        @Override
        public void onClick(View view) {
            if (mClickListener != null) mClickListener.onItemClick(view, getAdapterPosition());
        }
    }


    // allows clicks events to be caught
    void setClickListener(ItemClickListener itemClickListener) {
        this.mClickListener = itemClickListener;
    }

    // parent activity will implement this method to respond to click events
    public interface ItemClickListener {
        void onItemClick(View view, int position);
    }
}

配方列表模型

public class RecipeList {

    private Integer id;
    private Double ingredient_quantity;
    private String recipe;
    private String measurement_name;
    private String ingredient_name;
    private String description;
    private String ingredient_amount = String.valueOf(ingredient_quantity);
    public RecipeList(){

    }

    public RecipeList(String recipe, String ingredient_amount, String measurement_name, String ingredient_name, String description) {

        this.recipe = recipe;
        this.ingredient_amount = ingredient_amount;
        this.measurement_name = measurement_name;
        this.ingredient_name = ingredient_name;
        this.description = description;
    }

    public String getRecipe() {
        return recipe;
    }

    public void setRecipe(String recipe) {
        this.recipe = recipe;
    }

    public String getIngredient_amount() {
        return ingredient_amount;
    }

    public void setIngredient_amount(String ingredient_amount) {
        this.ingredient_amount = ingredient_amount;
    }

    public String getMeasurement_name() {
        return measurement_name;
    }

    public void setMeasurement_name(String measurement_name) {
        this.measurement_name = measurement_name;
    }

    public String getIngredient_name() {
        return ingredient_name;
    }

    public void setIngredient_name(String ingredient_name) {
        this.ingredient_name = ingredient_name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }
    @Override
    public String toString() {
        return "RecipeList{" +
                "id=" + id +
                ", ingredient_quantity=" + ingredient_quantity +
                ", recipe='" + recipe + '\'' +
                ", measurement_name='" + measurement_name + '\'' +
                ", ingredient_name='" + ingredient_name + '\'' +
                ", description='" + description + '\'' +
                ", ingredient_amount='" + ingredient_amount + '\'' +
                '}';
    }
}

更新：

这是导致故障的行：

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    holder.myTextView.setText(itemRecipe.get(position).toString());

}

Fragment_item

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <TextView
        android:id="@+id/quantity"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/text_margin"
        android:textSize="12sp" />

    <TextView
        android:id="@+id/measurement"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/text_margin"
        android:textSize="12sp" />

    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/text_margin"
        android:textSize="12sp" />

    <TextView
        android:id="@+id/description"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/text_margin"
        android:textSize="12sp" />

</LinearLayout>

布局xml

<androidx.constraintlayout.widget.ConstraintLayout 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">


    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tabLayout"
        android:layout_width="409dp"
        android:layout_height="wrap_content"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Recipe" />

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Meal Plan" />

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Shopping List" />
    </com.google.android.material.tabs.TabLayout>

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.5" />

    <ImageView
        android:id="@+id/recipeImage"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toTopOf="@+id/guideline4"
        app:layout_constraintEnd_toStartOf="@+id/guideline3"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/tabLayout" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.33" />

    <TextView
        android:id="@+id/descriptionText"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:text="TextView"
        app:layout_constraintBottom_toTopOf="@+id/guideline4"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/recipeImage"
        app:layout_constraintTop_toBottomOf="@+id/tabLayout" />

    <TextView
        android:id="@+id/courseText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:text="TextView"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/guideline4" />

    <TextView
        android:id="@+id/servingsText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:text="TextView"
        app:layout_constraintStart_toStartOf="@+id/guideline3"
        app:layout_constraintTop_toTopOf="@+id/guideline4" />

    <TextView
        android:id="@+id/costText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="8dp"
        android:text="TextView"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/courseText" />

    <TextView
        android:id="@+id/caloriesText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="8dp"
        android:text="TextView"
        app:layout_constraintStart_toStartOf="@+id/guideline3"
        app:layout_constraintTop_toBottomOf="@+id/servingsText" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/listIngredient"
        android:name="com.stu54259.plan2cook.Recipe"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="8dp"
        app:layoutManager="LinearLayoutManager"
        app:layout_constraintBottom_toTopOf="@+id/guideline7"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/caloriesText"
        tools:context=".Recipe"
        tools:listitem="@layout/fragment_item">

    </androidx.recyclerview.widget.RecyclerView>

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline7"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.66" />

    <TextView
        android:id="@+id/methodText"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:text="TextView"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/listIngredient" />


</androidx.constraintlayout.widget.ConstraintLayout>

更新

我改变了 myTextView = itemView.findViewById(R.id.listIngredient); 到 myTextView = itemView.findViewById(R.id.quantity);

recyclerView 现在正在显示 RecipeList{id=null, ingredients_quantity=null, recipe='Speedy chicken cous cous',measurement_name='tbsp',component_name='fresh coriander',description='chopped',成分数量 = 1} 然后这个对每种成分重复，而我希望它显示 1 汤匙切碎的新鲜香菜 有什么想法吗？