android - 如何从 ListView 中提取对象 - getItemAtPosition 不起作用

Question

我为我的 ListView 实现了一个自定义适配器。如何从特定列表项中提取对象。这是我的自定义适配器的外观:

MyCustomAdapter.java

public class MyCustomAdapter extends ArrayAdapter<DashboardBean> {


Context context;
int layoutResourceId;
DashboardBean currentMRB;
Vector<DashboardBean> data;

public MyCustomAdapter(Context context, int layoutResourceId, Vector<DashboardBean> data) 
{
    super(context,layoutResourceId,data);
    this.layoutResourceId = layoutResourceId;
    this.context=context;
    this.data = data;
}

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

    View row = convertView;
    MyStringReaderHolder holder;

    if(row==null)
    {
        LayoutInflater inflater = ((Activity)context).getLayoutInflater();
        row = inflater.inflate(layoutResourceId, parent,false);

        holder= new MyStringReaderHolder();

        holder.project = (TextView)row.findViewById(R.id.project);
        holder.workRequest = (TextView)row.findViewById(R.id.work_request);
        holder.startDate  = (TextView)row.findViewById(R.id.start_date);
        holder.status = (TextView) row.findViewById(R.id.status);

        row.setTag(holder);
    }
    else
    {
        holder=(MyStringReaderHolder) row.getTag();
    }

    DashboardBean mrb =data.elementAt(position);
    System.out.println("Position="+position);

     holder.project.setText(mrb.project);
    holder.workRequest.setText(mrb.workRequest);
    holder.startDate.setText(mrb.startDate);
    holder.status.setText(mrb.status);
    return row;
}





static class MyStringReaderHolder {
     TextView project, workRequest, startDate, status;

   }
}

这是 DashboardBean.java

 public class DashboardBean {

    public String project;
    public String workRequest;
    public String startDate;
    public String status;   

    public DashboardBean(String project,String workRequest,String startDate,String status)
    {
        this.project = project;
        this.workRequest = workRequest;
        this.startDate = startDate;
        this.status = status;
    }
}

这是我调用 onClickListener() 的 java fragment :

mListView.setOnItemClickListener(new OnItemClickListener() {
      public void onItemClick(AdapterView<?> myAdapter, View myView, 
            int myItemInt, long mylng) {
        TableRow tableRow = (TableRow) (mListView.getItemAtPosition(myItemInt));

        String project = ((TextView) tableRow.findViewById(R.id.project)).getText().toString();
        String workRequest = ((TextView) tableRow.findViewById(R.id.work_request)).getText().toString();
        String startDate = ((TextView) tableRow.findViewById(R.id.start_date)).getText().toString();
        String status = ((TextView) tableRow.findViewById(R.id.status)).getText().toString();

          showWorkRequest(project, workRequest, startDate, status);

      }

  });

和 xml 代码:

<?xml version="1.0" encoding="utf-8"?>
<TableRow xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tabRow1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    style="@style/BodyRow"
    android:gravity="center_horizontal" >

    <RelativeLayout 
    android:id="@+id/relativeLayout1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"

    android:gravity="center_horizontal" >

    <TextView
        android:id="@+id/status"
        android:layout_width="wrap_content"
        style="@style/BodyText"
        android:layout_height="wrap_content"

        android:layout_alignParentRight="true"
         android:textColor="@color/textColor"
        android:text="TextView" />

    <TextView
        android:id="@+id/start_date"
        style="@style/HourText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:text="TextView"  android:textColor="@color/textColor" android:textSize="10sp"/>

    <TextView
        android:id="@+id/project"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_toRightOf="@+id/start_date"
        android:gravity="center_horizontal"
        style="@style/LeftHeaderText"
        android:text="TextView" android:layout_marginLeft="5dp"
        android:textColor="@color/textColor" android:textStyle="bold"/>

    <TextView
        android:id="@+id/work_request"
        android:layout_width="wrap_content"
        style="@style/BodyText"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/project"
        android:layout_below="@+id/project"
        android:text="TextView"
         android:textColor="@color/textColor" />

</RelativeLayout>
</TableRow>

我想我不能像通常使用的那样使用 onClickListener，因为我是 extendind 自定义适配器。在那种情况下，他们可能有问题

public void onItemClick(AdapterView<?> myAdapter, View myView, 
            int myItemInt, long mylng)

但日志显示:DashboardBean 出现 ClassCastException。

无论如何，我无法修复它。谁能帮忙？

Answer 1

ClassCastException 是由 OnItemClickListener 中的以下行引起的:

TableRow tableRow = (TableRow) (mListView.getItemAtPosition(myItemInt));

那是因为您的适配器充满了 DashboardBean 实例。 getItemAtPosition 方法返回属于适配器使用的数据结构的对象，不是图形小部件的实例(TableRow，我假设)对象显示在哪个上。只是写:

DashboardBean board = (DashboardBean) (mListView.getItemAtPosition(myItemInt));

代替有问题的行就可以了。然后，您可以直接使用 DashboardBean 对象中的字段，而不是通过 TextView 和类似的 UI 元素。