如何在 RecyclerView 中制作动态微调器？答案

【问题标题】：How to make Dynamic Spinner inside RecyclerView?如何在 RecyclerView 中制作动态微调器？
【发布时间】：2021-09-13 02:50:11
【问题描述】：

我将创建一个 Dynamic CardView，其中包含 TextView (Item Name)、Spinner 等组件strong>（活动选择）和EditText（静态备注）。

我已经为数组中的每个列表设置/获取了 Item Name，但是对于 Spinner Item 我遇到了错误。

请参阅下文以供参考。谢谢！

1. FormActivity.java

    private void buildRecyclerView() {
       mRecyclerView = findViewById(R.id.rv_item); //RecyclerView
       mRecyclerView.setHasFixedSize(true);
       mLayoutManager = new LinearLayoutManager(this);
       mAdapter = new ItemAdapter(mItemList, this);

       mRecyclerView.setLayoutManager(mLayoutManager);
       mRecyclerView.setAdapter(mAdapter);
    }

mItemList，我要过去到 ItemAdapter.class

{
        "item_id": 1,
        "location_id": 1,
        "item_name": "Credit Back Door",
        "value": [
                "A",
                "B",
                "C"
            ]
        }
    },

{
        "item_id": 2,
        "location_id": 1,
        "item_name": "2F Admin Bridgeway",
        "value": [
                "D",
                "E",
                "F"
            ]
        }
    }

2. form_item.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView 
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:id="@+id/itemCard"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_rowWeight="1"
android:layout_columnWeight="1"
android:layout_gravity="fill"
android:layout_margin="8dp"
app:cardCornerRadius="20dp"
app:cardElevation="20dp">

<androidx.constraintlayout.widget.ConstraintLayout
    android:id="@+id/relativeLayout2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="8dp"
    android:padding="10dp"
    tools:layout_editor_absoluteX="4dp"
    tools:layout_editor_absoluteY="4dp">

    <TextView
        android:id="@+id/txt_item"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        android:text="1. Item"
        android:textAllCaps="false"
        android:textColor="#327034"
        android:textStyle="bold"
        app:layout_constraintTop_toTopOf="parent"
        tools:layout_editor_absoluteX="10dp" />

    <Spinner
        android:id="@+id/dd_activity"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="34dp"
        android:animateLayoutChanges="false"
        app:layout_constraintTop_toTopOf="parent"
        tools:layout_editor_absoluteX="9dp" />

    <EditText
        android:id="@+id/txt_remarks"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="68dp"
        android:hint="Remarks"
        app:layout_constraintTop_toTopOf="parent"
        tools:layout_editor_absoluteX="9dp" />

</androidx.constraintlayout.widget.ConstraintLayout>

</androidx.cardview.widget.CardView>

2.2 动态 CardView 用户界面 Please click here to see the picture

3. ItemAdapter.java

public class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ItemViewHolder> {
public ArrayList<ItemParams> mItemList;
public Context Context;

public ItemAdapter(ArrayList<ItemParams> itemList, Context context) {
    mItemList = itemList;
    Context = context;
}

public static class ItemViewHolder extends RecyclerView.ViewHolder {
    public TextView txt_item;
    public Spinner dd_activity;
    public EditText txt_remarks;
    public CardView itemCard;

    public ItemViewHolder(View itemView) {
        super(itemView);
        itemCard = itemView.findViewById(R.id.itemCard);
        txt_item = itemView.findViewById(R.id.txt_item);
        dd_activity = itemView.findViewById(R.id.dd_activity);
        txt_remarks = itemView.findViewById(R.id.txt_remarks);
    }
}

@NonNull
@Override
public ItemAdapter.ItemViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.form_item, parent, false);
    ItemAdapter.ItemViewHolder cvh = new ItemAdapter.ItemViewHolder(v);

    //SPINNER ITEM SAMPLE BUT IT WILL BE A DYNAMIC FROM ONE OF THE LIST
    List<String> list = new ArrayList<String>();
    list.add("list 1");
    list.add("list 2");
    list.add("list 3");

    ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(parent.getContext(),R.layout.form_item, list);
    dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    cvh.dd_activity.setAdapter(dataAdapter);

    return cvh;
}

@Override
public void onBindViewHolder(@NonNull ItemAdapter.ItemViewHolder holder, int position) {
    ItemParams mFormItem = mItemList.get(position);

    holder.txt_item.setText(mFormItem.getItem_name());
}

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

}

错误：

2021-07-01 13:28:34.645 7337-7337/com.unilab.healthcheck E/RecyclerView: No adapter attached; skipping layout

2021-07-01 13:28:35.050 7337-7337/com.unilab.healthcheck E/ArrayAdapter: You must supply a resource ID for a TextView

2021-07-01 13:28:35.053 7337-7337/com.unilab.healthcheck E/AndroidRuntime: FATAL EXCEPTION: main Process: com.unilab.healthcheck, PID: 7337 java.lang.IllegalStateException: ArrayAdapter requires the resource ID to be a TextView

【问题讨论】：

那么，微调器的错误是什么？
嗯，用构造函数也显示 ItemAdapter.ItemViewHolder 类。
您在 ArrayAdapter 之前创建 ItemViewHolder，这样新的 ItemHolder 将没有 ArrayAdapter。
@Matheus 请查看更新后的代码。谢谢！
@Zain 请查看更新后的帖子。谢谢！

标签： java android android-studio dynamic spinner

【解决方案1】：

由于您不必在适配器中初始化数组，而是可以在活动或片段中创建列表，无论您拥有什么，你可以试试这个 sn-ps（参考来自你的代码）

->首先您必须将此代码添加到活动或片段中

        //SPINNER ITEM SAMPLE
        List<String> list = new ArrayList<String>();
        list.add("list 1");
        list.add("list 2");
        list.add("list 3");
        recycleview.setAdapter(new ItemAdapter(getActivity(),list));

-> 然后

package com.brnd.pos.adapters;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ItemViewHolder> {
    Context context;
    List<String> list;

    public ItemAdapter(Context context, List<String> list) {
        this.context = context;
        this.list = list;
    }

    @NonNull
    @Override
    public ItemAdapter.ItemViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.form_item, parent, false);
        return new ItemAdapter.ItemViewHolder(v);
    }

    @Override
    public void onBindViewHolder(@NonNull ItemAdapter.ItemViewHolder holder, int position) {
        ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(parent.getContext(), R.layout.form_item, R.id.dd_activity, list);
        dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        cvh.dd_activity.setAdapter(dataAdapter);

        ItemParams mFormItem = mItemList.get(position);
        holder.txt_item.setText(mFormItem.getItem_name());
    }

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

    //below viewholder is just for your reference you have to find view id's
    public static class ItemViewHolder extends RecyclerView.ViewHolder {
        public ItemViewHolder(@NonNull View itemView) {
            super(itemView);
        }
    }
}

【讨论】：

感谢您的回复。后续问题，如果微调项的值取决于传递给 ItemAdapter 的列表怎么办？请查看更新后的帖子。再次感谢您。

【解决方案2】：

FormActivity.java

private void buildRecyclerView() {
        mRecyclerView = findViewById(R.id.rv_item); //RecyclerView
        mRecyclerView.setHasFixedSize(true);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mRecyclerView.setAdapter(new ItemAdapter(mItemList,getApplicationContext()));
    }

ItemAdapter.java

public class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ItemViewHolder> {

    public ArrayList<ItemParams> mItemList;
    public Context context;

    public ItemAdapter(ArrayList<ItemParams> itemList, Context context) {
        this.mItemList = itemList;
        this.context = context;
    }

    public static class ItemViewHolder extends RecyclerView.ViewHolder {
        public TextView txt_item;
        public Spinner dd_activity;
        public EditText txt_remarks;
        public CardView itemCard;

        public ItemViewHolder(View itemView) {
            super(itemView);
            itemCard = itemView.findViewById(R.id.itemCard);
            txt_item = itemView.findViewById(R.id.txt_item);
            dd_activity = itemView.findViewById(R.id.dd_activity);
            txt_remarks = itemView.findViewById(R.id.txt_remarks);
        }
    }

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

    @Override
    public void onBindViewHolder(@NonNull ItemViewHolder holder, int position) {
        //SPINNER ITEM SAMPLE BUT IT WILL BE A DYNAMIC FROM ONE OF THE LIST
        List<String> list = new ArrayList<String>();
        list.add("list 1");
        list.add("list 2");
        list.add("list 3");

        holder.dd_activity.setAdapter(
                new ArrayAdapter(context, android.R.layout.simple_spinner_dropdown_item, list));

        holder.txt_item.setText(mItemList.get(position).getItem_name());
    }

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

但我相信错误在 xml 中：

android.R.layout.simple_spinner_dropdown_item

如果错误仍然出现，请尝试切换到类似于此的 XML：

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/item_dropdown_textView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:padding="15dp"
    android:text="@string/texte"
    android:textAlignment="center"
    android:textSize="18sp"></TextView>

【讨论】：