使用Android中的dataSource信息填充下拉列表

Question

我正在尝试使用数据源中的用户列表填充下拉列表，我从数据库中获取该数据源。我为此创建了自己的布局，因为我需要一些额外的信息，如电子邮件地址以及用户的名称和标题。我在下面粘贴的布局没有这个，因为我想首先填充全名。

hcp_dropdown.xml（布局）：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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="wrap_content"
android:background="@color/grey_98"
android:orientation="horizontal">

<android.support.constraint.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/Row_assessment_file_for_list_assessment_text_name"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="4dp"
        android:textColor="#000000"
        android:textSize="15sp"
        android:textStyle="normal"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="MissingConstraints"
        tools:text="Lastname, Firstname" />

</android.support.constraint.ConstraintLayout>

我意识到我不得不给这个视图充气，所以我在我的适配器中做了这个。

HCPListAdapter.java（适配器）：

public class HCPListAdapter extends ArrayAdapter<User> {
public HCPListAdapter(Context context, List<User> users){
    super(context, 0, users);
}

@NonNull
@Override
public View getView(int position, View convertView, @NonNull ViewGroup parent) {

    if (convertView == null) {
        convertView = LayoutInflater.from(getContext()).inflate(R.layout.hcp_dropdown, parent, false);
    }
    HCPViewHolder viewHolder = (HCPViewHolder) convertView.getTag();

    if (viewHolder == null) {
        viewHolder = new HCPViewHolder();
        viewHolder.name = (TextView) convertView.findViewById(R.id.Row_assessment_file_for_list_assessment_text_name);

        convertView.setTag(viewHolder);
    }

    User user = getItem(position);
    if (user != null) {
        viewHolder.name.setText(user.getTitle() + ". " + user.getLastname() + ", " + user.getFirstname());
    } else {
        viewHolder.name.setText(R.string.error_unknown);
        return convertView;
    }
    return convertView;
}

    private class HCPViewHolder{
        public TextView name;
    }
}

这是我的问题当我现在尝试使用此适配器作为我的微调器并用信息填充它时，它显示第一个用户，然后当我单击下拉按钮时它崩溃并在logcat中给我一个错误（在我的RegisterActivity.java下面）

RegisterActivity.java（活动）

 HCPListAdapter HCPAdapter = new HCPListAdapter(RegisterActivity.this, MainActivity.sListHCPs);
        mspinnerCompleteHCP1.setAdapter(HCPAdapter);

...我在应用程序崩溃时收到此logcat消息：

FATAL EXCEPTION: main
                                                                     Process: co.uk.mednet.mednet_ghana, PID: 8483
                                                                     android.content.res.Resources$NotFoundException: Resource ID #0x0
                                                                         at android.content.res.ResourcesImpl.getValue(ResourcesImpl.java:202)
                                                                         at android.content.res.Resources.loadXmlResourceParser(Resources.java:2970)
                                                                         at android.content.res.Resources.getLayout(Resources.java:1986)
                                                                         at android.view.LayoutInflater.inflate(LayoutInflater.java:425)
                                                                         at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:380)
                                                                         at android.widget.ArrayAdapter.getDropDownView(ArrayAdapter.java:457)
                                                                         at android.widget.Spinner$DropDownAdapter.getDropDownView(Spinner.java:1121)
                                                                         at android.widget.Spinner$DropDownAdapter.getView(Spinner.java:1117)
                                                                         at android.widget.Spinner.measureContentWidth(Spinner.java:958)
                                                                         at android.widget.Spinner$DropdownPopup.computeContentWidth(Spinner.java:1369)
                                                                         at android.widget.Spinner$DropdownPopup.show(Spinner.java:1408)
                                                                         at android.widget.Spinner.performClick(Spinner.java:869)
                                                                         at android.support.v7.widget.AppCompatSpinner.performClick(AppCompatSpinner.java:438)
                                                                         at android.view.View$PerformClick.run(View.java:23748)
                                                                         at android.os.Handler.handleCallback(Handler.java:751)
                                                                         at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                         at android.os.Looper.loop(Looper.java:154)
                                                                         at android.app.ActivityThread.main(ActivityThread.java:6776)
                                                                         at java.lang.reflect.Method.invoke(Native Method)
                                                                         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1520)
                                                                         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1410)

Answer 1

试试这个代码。

public class HCPListAdapter extends ArrayAdapter<User> {
List<User> users;
LayoutInflater inflater;

public HCPListAdapter(Activity context, int resouceId, int textviewId, List<User> list){
    super(context,resouceId,textviewId, list);
    users = list;
    inflater = context.getLayoutInflater();
}

@NonNull
@Override
public View getView(int position, View convertView, @NonNull ViewGroup parent) {

    if (convertView == null) {
        convertView = inflater.inflate(R.layout.hcp_dropdown, parent, false);
    }
    TextView name = convertView.findViewById(R.id.Row_assessment_file_for_list_assessment_text_name);

    User user = getItem(position);
    if (user != null) {
        name.setText(user.getTitle() + ". " + user.getLastname() + ", " + user.getFirstname());
    } else {
        name.setText(R.string.error_unknown);
        return convertView;
    }
    return convertView;
}

@Override
public int getCount() {
    return users.size();
}

@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
    if(convertView == null){
        convertView = inflater.inflate(R.layout.hcp_dropdown, parent, false);
    }
    User user = getItem(position);
    TextView txtTitle = convertView.findViewById(R.id.Row_assessment_file_for_list_assessment_text_name);
    txtTitle.setText(user.getTitle() + ". " + user.getLastname() + ", " + user.getFirstname());
    return convertView;
    }
}