通过适配器膨胀 json 数据

Posted 2023-04-19

【中文标题】通过适配器膨胀 json 数据

【英文标题】：Inflating json data via Adapter

【发布时间】：2019-10-31 13:53:39

【问题描述】：

我正在尝试将 json 数据膨胀到我的列表项中，但我得到了一个空白屏幕。我要显示的数据来自嵌套的 json 数组。所以我使用改造和 gson 创建了对象。我制作了 2 个对象（蛋糕和配料），配料是 List 类型。我还提供了 json 文件的图像。

public class CakesItem  

    @SerializedName("id")
    private int mId;

    @SerializedName("name")
    private String mName;

    @SerializedName("ingredients")
    private List<Ingredient> mIngredients;


    public int getmId() 
        return mId;
    

    public String getmName() 
        return mName;
    

    public List<Ingredient> getmIngredients() 
        return mIngredients;
    

public class Ingredient implements Parcelable 


    private double quantity;

    private String measure, ingredient;



    public String getmMeasure() 
        return measure;
    

    public double getmQuantity() 
        return quantity;
    


    public String getmIngredient() 
        return ingredient;
    

public class IngredientsAdapter extends RecyclerView.Adapter<IngredientsAdapter.IngredientsHolder> 

    private List<Ingredient> ingredients = new ArrayList<>();


    @NonNull
    @Override
    public IngredientsHolder onCreateViewHolder(@NonNull ViewGroup parent, int i) 

        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.ingredient_list_item, parent, false);
        return new IngredientsHolder(view);
    

    @Override
    public void onBindViewHolder(@NonNull final IngredientsHolder Holder, int position) 

        Holder.onBind(ingredients.get(position));

    

    @Override
    public int getItemCount() 
        return ingredients.size();
    

    void getIngredientsData(List<Ingredient> ingredients) 
        this.ingredients.clear();
        this.ingredients = ingredients;
        notifyDataSetChanged();
    

    class IngredientsHolder extends RecyclerView.ViewHolder 


        private final TextView mIngredientsTV;

        IngredientsHolder(@NonNull View itemView) 
            super(itemView);

            mIngredientsTV = itemView.findViewById(R.id.ingredients_list_tv);
        


        void onBind(Ingredient ingredients) 
            mIngredientsTV.setText(formatString(ingredients.getmIngredient(), String.valueOf(ingredients.getmQuantity()), ingredients.getmMeasure()));
        

        private String formatString(String i, String q, String m) 
            return " (" + q + " " + m + ") " + i;
        
    





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

        mIngredientsList = new ArrayList<>();
        IngredientsAdapter ingredientsAdapter = new IngredientsAdapter();
        ingredientsRecyclerView = findViewById(R.id.ingredients_recycler_view);
        ingredientsRecyclerView.setHasFixedSize(true);
        ingredientsRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        ingredientsRecyclerView.setAdapter(ingredientsAdapter);

        ingredientsAdapter.getIngredientsData(mIngredientsList);


        mRecipeImage = findViewById(R.id.recipe_cake_image_iv);
        Drawable myDrawable = getResources().getDrawable(R.drawable.nutella_pie_2);
        mRecipeImage.setImageDrawable(myDrawable);

        mCakeTitle = findViewById(R.id.cake_title);
        mCakeTitle.setText("Nutella Pie");

    

【问题讨论】：

您是否为您的RecyclerView 设置了物品装饰器？ android.jlelse.eu/…

不，我没有添加物品装饰器，应该吗？

你绝对需要。尝试添加一个。

【参考方案1】：

您在哪里将 JSON 解析为对象？从代码中，您刚刚为您的适配器设置了一个空列表。 尝试： 在 MainActivity：

@Override
public void onItemClicked(CakesItem cakesItem) 
    Intent detailIntent = new Intent(this, recipe_detail.class);
    detailIntent.putExtra("Ingredients", cakesItem.getmIngredients());
    startActivity(detailIntent);

在recipe_detail中：

private List<Ingredient> mIngredientsList = new ArrayList<>();

@Override
protected void onCreate(Bundle savedInstanceState) 
    ...
    mIngredientsList = getIntent().getSerializableExtra("Ingredients");;
    IngredientsAdapter ingredientsAdapter = new IngredientsAdapter();
    ingredientsAdapter.getIngredientsData(mIngredientsList);
    ...

【讨论】：

哦，我认为你正在做一些事情，但如果我在我的 activity_recipe_detail 中实现该行，“json”将不会被解析，因为网络调用是在 Main_activity 上实现的。 github.com/Pureskill75/BakingApp/blob/master/app/src/main/java/…

@pureskill75 已编辑，请尝试。

全部完成，谢谢，我用 parcelable 替换了可序列化