用Android Studio实现外卖订餐系统显示代码

抱歉，这个问题比较复杂，需要涉及到数据库、后端接口等多个方面的知识。以下是一个简单的示例代码，仅供参考：

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private RecyclerView mRecyclerView;
    private List<Dish> mDishList = new ArrayList<>();
    private DishAdapter mAdapter;

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

        // 初始化 RecyclerView
        mRecyclerView = findViewById(R.id.recycler_view);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mAdapter = new DishAdapter(mDishList);
        mRecyclerView.setAdapter(mAdapter);

        // 加载菜品数据
        loadDishes();
    }

    private void loadDishes() {
        // 发送网络请求获取菜品列表
        RequestQueue queue = Volley.newRequestQueue(this);
        String url = "http://example.com/api/dishes";
        JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null,
                response -> {
                    // 解析服务器返回的 JSON 数据
                    JSONArray jsonArray = response.optJSONArray("data");
                    for (int i = 0; i < jsonArray.length(); i++) {
                        JSONObject jsonObject = jsonArray.optJSONObject(i);
                        Dish dish = new Dish();
                        dish.setName(jsonObject.optString("name"));
                        dish.setPrice(jsonObject.optDouble("price"));
                        dish.setDescription(jsonObject.optString("description"));
                        mDishList.add(dish);
                    }
                    // 刷新 RecyclerView
                    mAdapter.notifyDataSetChanged();
                },
                error -> Toast.makeText(this, "加载菜品失败", Toast.LENGTH_SHORT).show());
        queue.add(request);
    }
}

Dish.java

public class Dish {
    private String name;
    private double price;
    private String description;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }
}

DishAdapter.java

public class DishAdapter extends RecyclerView.Adapter<DishAdapter.ViewHolder> {
    private List<Dish> mDishList;

    public DishAdapter(List<Dish> dishList) {
        mDishList = dishList;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_dish, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        Dish dish = mDishList.get(position);
        holder.nameTextView.setText(dish.getName());
        holder.priceTextView.setText(String.format(Locale.getDefault(), "%.2f 元", dish.getPrice()));
        holder.descriptionTextView.setText(dish.getDescription());
    }

    @Override
    public int getItemCount() {
        return mDishList.size();
    }

    static class ViewHolder extends RecyclerView.ViewHolder {
        TextView nameTextView;
        TextView priceTextView;
        TextView descriptionTextView;

        ViewHolder(View view) {
            super(view);
            nameTextView = view.findViewById(R.id.text_name);
            priceTextView = view.findViewById(R.id.text_price);
            descriptionTextView = view.findViewById(R.id.text_description);
        }
    }
}

item_dish.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:id="@+id/text_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="24sp"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/text_price"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="18sp" />

    <TextView
        android:id="@+id/text_description"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="16sp"
        android:layout_marginTop="8dp" />

</LinearLayout>

此示例代码仅实现了菜品列表的显示，仍需后端接口和数据库支持才能实现完整的外卖订餐系统。