android - RecyclerView 中的 Android Spinners 问题

Question

我有一个包含复杂项目的 RecyclerView，由一个包含 TextView 小部件、一个 Spinner 小部件和一个 的类表示EditText 小部件。 (想一想任务列表，其中包含任务名称、用于选择任务已到达哪个处理阶段的旋转器，以及该处理阶段的完成日期。)

此列表的数据来自文件，对列表中项目的更改将写回到文件中。当用户稍后返回应用程序时，列表应反射(reflect)他之前看到的数据。

1. 目前，我的应用程序显示项目列表，只是我不知道如何将 Spinner 的初始值设置为从文件中读取的值。 如何为列表中的每个微调器设置不同的初始选择？

2. 目前，当用户从 Spinner 中进行选择时，列表会消失并且选择不会显示为用户的选择。我从另一个帖子看到 - Android: Spinner not showing the selected value - 我应该调用 setSelection()(由 AbsSpinner 的 Spinner 类继承)。但这没有任何作用。在 XML 布局中，我的 Spinner 具有:android:textColor="@color/colorPrimaryDark" 所以我认为文本的颜色与背景相匹配不是问题。看这个List of Tasks . 如何保留用户的选择？

3. 在 OnItemSelected() 中，我如何告诉 Activity 记录所选值以便将其保存回文件？示例代码我'我在网上发现通常只使用 Toast 来显示选择已注册。我想我需要知道 RecyclerView 中的哪个项目包含这个 Spinner...

这里是详细信息...

activity_task.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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"
    android:background="@color/colorBG"
    tools:context="org.myorg.myapp.DetailActivity">

    ...

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rvChapList"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        app:layout_constraintTop_toBottomOf="@+id/txtTaskLabel"
        android:layout_marginTop="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toRightOf="@+id/imgBorder"
        app:layout_constraintRight_toRightOf="parent"
        />

</android.support.constraint.ConstraintLayout>

subtask_detail.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="24dp"
    android:background="@color/colorBG"
    android:id="@+id/subtask_detail"
    >

    <android.support.constraint.Guideline
        android:id="@+id/LGuideLine2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:orientation="vertical"
        app:layout_constraintGuide_begin="40dp"
        tools:layout_editor_absoluteY="0dp"
        tools:layout_editor_absoluteX="40dp" />

    <android.support.constraint.Guideline
        android:id="@+id/RGuideLine2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:orientation="vertical"
        app:layout_constraintGuide_begin="280dp"
        tools:layout_editor_absoluteY="0dp"
        tools:layout_editor_absoluteX="280dp" />

    <TextView
        android:id="@+id/txtChapNum"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:paddingTop="6dp"
        tools:text="150"
        android:textAppearance="@style/TextAppearance.AppCompat"
        android:textColor="@color/colorPrimaryDark"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@+id/LGuideLine2"
        />

    <Spinner
        android:id="@+id/spnSteps"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:spinnerMode="dialog"
        tools:text="Quality Check"
        android:prompt="@string/step_prompt"
        style="@android:style/Widget.Holo.Light.Spinner"
        android:entries="@array/step_array"
        android:textColor="@color/colorPrimaryDark"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toRightOf="@+id/LGuideLine2"
        app:layout_constraintRight_toLeftOf="@+id/RGuideLine2"
        />

    <EditText
        android:id="@+id/edtDate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="date"
        android:paddingTop="0dp"
        android:paddingBottom="0dp"
        android:paddingStart="0dp"
        android:paddingEnd="0dp"
        tools:text="12-30-2020"
        android:textSize="14sp"
        android:textColor="@color/colorPrimaryDark"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toRightOf="@+id/RGuideLine2"
        app:layout_constraintRight_toRightOf="parent"
        />

</android.support.constraint.ConstraintLayout>

DetailActivity.java:

package org.myorg.myapp;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;

import java.util.ArrayList;

public class DetailActivity extends AppCompatActivity {
    private RecyclerView _rv;
    private LayoutInflater _li;
    private SubtaskDetailAdapter _adapter;
    private ArrayList _alEntries;
    private ArrayList _alTaskEntries;
    private String _sTaskName = null;
    private static final String EXTRA_TASK = "EXTRA_TASK";

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

        Intent i = getIntent();
        _sTaskName = i.getStringExtra(EXTRA_TASK);
        TextView tvTaskName = (TextView) findViewById(R.id.txtTaskName2);
        tvTaskName.setText(_sTaskName);

        // create item detail array & populate it based on task item array
        _alEntries = Globals.getArrayList();
        _alTaskEntries = new ArrayList();
        PopulateTaskDetailList();

        _rv = (RecyclerView) findViewById(R.id.rvChapList);
        _li = getLayoutInflater();
        _rv.setLayoutManager(new LinearLayoutManager(this));

        _adapter = new SubtaskDetailAdapter();
        _rv.setAdapter(_adapter);
    }

    public void PopulateTaskDetailList() {
        int iNumEntries = _alEntries.size();
        String sSubtask = "";
        TaskItem tiEntry = null;
        DetailItem diEntry = null;

        // extract subtasks for indicated task
        for (int i = 0; i < iNumEntries; i++) {
            tiEntry = (TaskItem) _alEntries.get(i);

            // if this task entry has the indicated Task name, save it's data
            if (tiEntry.get_TaskName().equals(_sTaskName)) {
                diEntry = new DetailItem(tiEntry.get_Subtask(),
                                         tiEntry.get_StepCompleted(),
                                         tiEntry.get_DateCompleted());

                _alTaskEntries.add(diEntry);
            }
        }
    }

    private class DetailItem {
        private String _sSubTaskName = "";
        private String _sStep = "";
        private String _sDate = "";

        private DetailItem(String sSubTaskName, String sStep, String sDate) {
            _sSubTaskName = sSubTaskName;
            _sStep = sStep;
            _sDate = sDate;
        }

        private String get_Subtask() { return _sSubTaskName; }

        public void set_Subtask(String sTaskName) { _sSubTaskName = sTaskName; }

        private String get_Step() { return _sStep; }

        public void set_Step(String sStep) { _sStep = sStep; }

        private String get_Date() { return _sDate; }

        public void set_Date(String sDate) { _sDate = sDate; }
    }

    private class SubtaskDetailAdapter extends RecyclerView.Adapter<SubtaskDetailAdapter.DetailViewHolder> {

        /**
         * Inflates (creates & fills) a new subtask_detail View, and then creates/returns a new
         * DetailViewHolder object for that view.
         * @param parent Unfortunately the docs currently don't explain this at all :(
         * @param viewType Unfortunately the docs currently don't explain this at all :(
         * @return
         */
        @Override
        public SubtaskDetailAdapter.DetailViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            // "inflate" (create & fill) a new holder / container view based on the task_item
            // layout, without "attaching" it to the parent view
            View v = _li.inflate(R.layout.subtask_detail, parent, false);

            // create an instance of DetailViewHolder based on this "inflated" "holder" view
            return new SubtaskDetailAdapter.DetailViewHolder(v);
        }

        /**
         * This method "Binds" or assigns Data (from _alTaskEntries) to each SubtaskDetail (ViewHolder).
         * @param holder The SubtaskDetail instance at a given position in the list
         * @param position The current position of the SubtaskDetail we are Binding to, based upon
         *                 our (listOfData). So for the second ViewHolder we create, we'll bind data
         *                 from the second Item in listOfData.
         */
        @Override
        public void onBindViewHolder(SubtaskDetailAdapter.DetailViewHolder holder, int position) {
            // the ViewHolder data
            DetailItem currentItem = (DetailItem) _alTaskEntries.get(position);

            holder._tvSubtask.setText(currentItem.get_Subtask());
            holder._etDate.setText(currentItem.get_Date());
            holder._spSteps.setSelection(position, true);
        }

        /**
         * This method helps our Adapter determine how many ViewHolders it needs to create,
         * based on the size of the Dataset (List) it is working with.
         * Returning 0 here would tell our Adapter not to make any Items.
         *
         * @return the size of the dataset to be represented in the RecyclerView
         **/
        @Override
        public int getItemCount() { return _alTaskEntries.size(); }

        /**
         * A ViewHolder is a container for a set of Views we want to populate with Data
         **/
        class DetailViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

            // view holders for views to bind in the layout
            private TextView  _tvSubtask;
            private EditText  _etDate;
            private Spinner   _spSteps;
            private ViewGroup _vgContainer;

            private DetailViewHolder(View itemView) {
                super(itemView);

                // use itemView with findViewByID, because we are looking for an ID in
                // the SubtaskDetail view container we created / inflated above
                _tvSubtask = (TextView) itemView.findViewById(R.id.txtChapNum);
                _spSteps = (Spinner) itemView.findViewById(R.id.spnSteps);
                _etDate = (EditText) itemView.findViewById(R.id.edtDate);

                _vgContainer = (ViewGroup) itemView.findViewById(R.id.subtask_detail);

                _spSteps.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                    @Override
                    public void onItemSelected(AdapterView<?> adapter, View v,
                                               int position, long id) {
                        // On selecting a spinner item
                        String sStep = adapter.getItemAtPosition(position).toString();

                        _spSteps.setSelection(position);
                    }

                    @Override
                    public void onNothingSelected(AdapterView<?> arg0) {
                        // TODO Auto‐generated method stub
                    }
                });

                /* We can pass "this" as an Argument, because DetailViewHolder implements the
                   View.OnClickListener interface. */
                _vgContainer.setOnClickListener(this);
            }

            @Override
            public void onClick(View v) {
                // currently unused
            }
        }
    }
}

感谢您在我尝试学习这些东西时提供的任何帮助!

新信息

我已经为我的问题 #3 找到了解决方案，尽管感觉很麻烦。可能有更好的方法，但由于没有人启发我，我只剩下这个了。

要在 RecyclerView 中显示的数据数组是 DetailItem 对象数组。我在 DetailItem 类中添加了另一个实例变量来保存将与该子任务步骤相关联的 Spinner View 。

这是更新后的 DetailItem 类定义:

private class DetailItem {
    private String   _sSubTaskName = "";
    private String   _sStep = "";
    private Spinner  _spSteps;
    private String   _sDate = "";

    private DetailItem(String sSubTaskName, String sStep, String sDate) {
    _sSubTaskName = sSubTaskName;
    _sStep = sStep;
    _sDate = sDate;
    }

    private String get_Subtask() { return _sSubTaskName; }
    public void set_Subtask(String sTaskName) { _sSubTaskName = sTaskName; }
    private String get_Step() { return _sStep; }
    public void set_Step(String sStep) { _sStep = sStep; }
    private Spinner get_Spin() { return _spSteps; }
    public void set_Spin(Spinner spSteps) { _spSteps = spSteps; }
    private String get_Date() { return _sDate; }
    public void set_Date(String sDate) { _sDate = sDate; }
}

我修改了适配器以将显示/选择它的 Spinner 与任务步骤一起存储。我还移动了代码以将 Spinner 的监听器从 ViewHolder 移动到 Adapter。

这是更新后的 SubtaskDetailAdapter 类定义及其扩展的 onBindViewHolder 方法:

private class SubtaskDetailAdapter extends RecyclerView.Adapter<SubtaskDetailAdapter.DetailViewHolder> {
    /** no changes */
    @Override
    public SubtaskDetailAdapter.DetailViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // ...
    }

    @Override
    public void onBindViewHolder(SubtaskDetailAdapter.DetailViewHolder holder, int position) {
        // the ViewHolder data
        DetailItem currentItem = (DetailItem) _alTaskEntries.get(position);

        holder._tvSubtask.setText(currentItem.get_Subtask());
        holder._etDate.setText(currentItem.get_Date());

        // store the spinner in the DetailItem object
        currentItem.set_Spin(holder._spSteps);

        // store DetailItem object in the array
        _alTaskEntries.set(position, currentItem);

        // look for Spinner step matching this entry's step
        String sStep = currentItem.get_Step();
        int iSel = 0;
        while (iSel < sSteps.length && !sSteps[iSel].equals(sStep))
            iSel++;

        // if matching step is found, set Spinner to show it
        if (iSel < sSteps.length) holder._spSteps.setSelection(iSel, true);

        // if matching step isn't found, show error message
        else Toast.makeText(getApplicationContext(),
                            "Unrecognized Step: " + sStep,
                            Toast.LENGTH_SHORT).show();

        // set listener for spinner selections
        holder._spSteps.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapter, View v,
                                       int position,           long id) {
                // get selected step
                String sStep = adapter.getItemAtPosition(position).toString();

                DetailItem currentItem = null;
                int iNumDetails = _alTaskEntries.size();
                int iDetail = 0;
                // fast-forward to array entry for this adapter (spinner)
                while (iDetail < iNumDetails) {
                    currentItem = (DetailItem) _alTaskEntries.get(iDetail);
                    if (currentItem.get_Spin().equals(adapter))
                        break;
                    else
                        iDetail++;
                }

                // if found, save it in the array of detail items
                if ((iDetail < iNumDetails) && (currentItem != null)) {
                    currentItem.set_Step(sStep);
                    _alTaskEntries.set(iDetail, currentItem);
                }

                adapter.setSelection(position);
            }

            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
                // TODO Auto-generated method stub
            }
        });
    }

我删除了 ViewHolder 类中的代码以在容器 View 上设置 OnClickListener，因为我不想响应对 RecyclerView 项目的点击，而只想响应其中的各个 View 。需要一个空的 OnClick，因为 holder 被声明为实现 OnClickListener 接口(interface)(我不知道这是否需要)。

这是更新的(更简单的)ViewHolder 类:

class DetailViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
    // view holders for views to bind in the layout
    private TextView  _tvSubtask;
    private EditText  _etDate;
    private Spinner   _spSteps;

    private DetailViewHolder(View itemView) {
        super(itemView);

        // use itemView with findViewByID, because we are looking for an ID in
        // the SubtaskDetail view container we created / inflated above
        _tvSubtask = (TextView) itemView.findViewById(R.id.txtChapNum);
        _spSteps = (Spinner) itemView.findViewById(R.id.spnSteps);
        _etDate = (EditText) itemView.findViewById(R.id.edtDate);
    }

    @Override
    public void onClick(View v) {
        // currently unused
    }
}

我的问题 #1 和 #2 仍未解决，这使得我的应用程序目前无法使用...有人想要解决这个问题吗？？？

Answer 1

我不知道您的代码将如何实现，但我会尝试通过示例回答您的问题来帮助您。

1) 如何为列表中的每个微调器设置不同的初始选择？

如果你想在 Spinner 中存储一个对象列表。

类

public class SpinnerItem {

    private String name;
    private int position;

    public SpinnerItem(String name, int position) {
        this.name = name;
        this.position = position;
    }

    public String getName() {
        return name;
    }

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

    public int getPosition() {
        return position;
    }

    public void setPosition(int position) {
        this.position = position;
    }

    @Override
    public String toString() {
        return this.name;
    }
}

微调器

ArrayList<SpinnerItem> spinnerItems = new ArrayList<>();
Spinner spinner = (Spinner) findViewById(R.id.spinner);

// Creating the items
for(int i=0; i<20; i++){
    spinnerItems.add(new SpinnerItem("A"+(i+1), i));
}

ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, spinnerItems);

spinner.setAdapter(adapter);
spinner.setSelection(10); // To select A11

2) 如何保留用户的选择？

要获取所选项目，您必须使用 setOnItemSelectedListener .

spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int position, long id) {
                SpinnerItem itemSelected = (SpinnerItem) adapterView.getItemAtPosition(position);
                Toast.makeText(view.getContext(), itemSelected.toString(), Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {

            }
        });

我通常将 Spinner 变量作为 Activity 类中的属性。您可以创建一个变量作为属性并调用 spItemSelected 来存储所选元素(在我的代码中将 SpinnerItem itemSelected 替换为 spItemSelected)。

3) 如何让 Activity 记录所选值以便将其保存回文件？

如果您在类 Activity 中选择元素作为属性，则可以更容易地从任何函数调用它以将其存储在文件中。我不确定你什么时候想要保存文件。