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我想将从 Web 服务获取的一些数据绑定到自定义列表视图...我的列表视图有一个图像视图和三个文本视图...

我读过的大多数教程都建议应该制作一个适配器类，所以我目前编写了一个如下所示的适配器：

public class InboxAdapter extends BaseAdapter {

    private Context context;

    private List<MailInbox> mails;

    public InboxAdapter(Context context, List<MailInbox> mails)
    {
        this.context = context;
        this.mails = mails;
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return mails.size();
    }

    @Override
    public Object getItem(int item) {
        // TODO Auto-generated method stub
        return mails.get(item);
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }

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

        MailInbox entry = mails.get(position);

        if(convertView == null)
        {
            LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.mail_list_row, null);
        }

        ImageView mailImg = (ImageView)convertView.findViewById(R.list.mail_thumb);
        //Set the appropriate image - either unread or read

        TextView author = (TextView)convertView.findViewById(R.list.mail_text);
        TextView body = (TextView)convertView.findViewById(R.list.mail_detail);
        TextView date = (TextView)convertView.findViewById(R.list.mail_date);

        author.setText(entry.AuthorName);
        body.setText(entry.MessageBody);
        date.setText(entry.CreatedAt);

        return convertView;
    }
}

所以这是我卡住的部分。我现在有一个适配器，但我不完全确定如何使用它......

在具有列表视图的活动中：

更新：

好的，所以我正在尝试像这样填充适配器：

private void setUpList()
{
    list = (ListView)findViewById(R.id.mail_list);      

    final List<MailInbox> mails = new ArrayList<MailInbox>();

    for(int i = 0; i < mMessages.myMail.size(); i++)
    {
        MailInbox inbox = new MailInbox();

        inbox.setProperty(0, mMessages.myMail.get(i).CreatedAt);
        inbox.setProperty(1, mMessages.myMail.get(i).MessageBody);
        inbox.setProperty(3, mMessages.myMail.get(i).AuthorName);
        inbox.setProperty(4, mMessages.myMail.get(i).IsRead);//used to determine the image that will be in the imageview

        mails.add(inbox);
    }

    // Just to check if it's added properly - it outputs 5
    int length = mails.size();
    System.out.println("Size: " + length);

    InboxAdapter adapter = new InboxAdapter(this, mails);

    list.setAdapter(adapter);
}

但是在 list.setAdapter(adapter) 上，我得到一个 Nullpointer 异常

整个错误：

05-14 17:43:17.855: E/AndroidRuntime(976): FATAL EXCEPTION: main
05-14 17:43:17.855: E/AndroidRuntime(976): java.lang.NullPointerException
05-14 17:43:17.855: E/AndroidRuntime(976):  at com.cim.daycare.InboxActivity.setUpList(InboxActivity.java:67)
05-14 17:43:17.855: E/AndroidRuntime(976):  at com.cim.daycare.InboxActivity.access$2(InboxActivity.java:43)
05-14 17:43:17.855: E/AndroidRuntime(976):  at com.cim.daycare.InboxActivity$GetMails.onPostExecute(InboxActivity.java:96)
05-14 17:43:17.855: E/AndroidRuntime(976):  at com.cim.daycare.InboxActivity$GetMails.onPostExecute(InboxActivity.java:1)
05-14 17:43:17.855: E/AndroidRuntime(976):  at android.os.AsyncTask.finish(AsyncTask.java:417)
05-14 17:43:17.855: E/AndroidRuntime(976):  at android.os.AsyncTask.access$300(AsyncTask.java:127)
05-14 17:43:17.855: E/AndroidRuntime(976):  at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
05-14 17:43:17.855: E/AndroidRuntime(976):  at android.os.Handler.dispatchMessage(Handler.java:99)
05-14 17:43:17.855: E/AndroidRuntime(976):  at android.os.Looper.loop(Looper.java:123)
05-14 17:43:17.855: E/AndroidRuntime(976):  at android.app.ActivityThread.main(ActivityThread.java:3683)
05-14 17:43:17.855: E/AndroidRuntime(976):  at java.lang.reflect.Method.invokeNative(Native Method)
05-14 17:43:17.855: E/AndroidRuntime(976):  at java.lang.reflect.Method.invoke(Method.java:507)
05-14 17:43:17.855: E/AndroidRuntime(976):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-14 17:43:17.855: E/AndroidRuntime(976):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-14 17:43:17.855: E/AndroidRuntime(976):  at dalvik.system.NativeStart.main(Native Method)

从做一些谷歌，听起来问题可能出在xml文件上......我有两个xml，一个叫做mail_list，一个叫做mail_list_row......

列表：

<?xml version="1.0" encoding="utf-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mail_list"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_weight="2"
    android:drawSelectorOnTop="false" >    
</ListView>

排：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="48dip"
    android:background="@drawable/listselector"
    >
    <ImageView
        android:id="@+list/mail_thumb"
        android:layout_width="30dip"
        android:layout_height="30dip"
        android:layout_centerVertical="true"
        android:layout_alignParentLeft="true"
        android:contentDescription="@string/imgdesc"
        />
    <TextView
        android:id="@+list/mail_text"
        android:layout_toRightOf="@+list/mail_thumb"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="14dip"
        android:layout_marginLeft="8dip"
        android:layout_centerVertical="false"
        android:singleLine="true"
        android:ellipsize="end"
        android:textStyle="bold"
        android:textColor="@android:color/white"
        />
    <TextView 
        android:id="@+list/mail_detail"
        android:layout_toRightOf="@+list/mail_thumb"
        android:layout_below="@+list/mail_text"
        android:layout_width="100dip"
        android:layout_height="wrap_content"
        android:textSize="12dip"
        android:layout_marginLeft="8dip"
        android:layout_centerVertical="false"
        android:singleLine="true"
        android:ellipsize="end"
        android:textColor="@color/grey"     
        />
    <TextView 
        android:id="@+list/mail_date"
        android:layout_toRightOf="@+list/mail_detail"
        android:layout_below="@+list/mail_text"
        android:layout_width="100dip"
        android:layout_height="wrap_content"
        android:textSize="12dip"
        android:singleLine="true"
        android:ellipsize="end"
        android:textColor="@color/grey"
        android:layout_alignParentRight="true"      
        />
</RelativeLayout>
4

2 回答 2

1

在 setUpList 方法中，您将要使用的数据传递给适配器。

然后构造函数将它们的集合分配给适配器内的集合。getView 然后提取相关数据（1 x 1）并将其放入视图的正确元素中

于 2012-05-14T13:52:18.920 回答
1

尝试类似的东西

private void setUpList()
{
    list = (ListView)findViewById(R.id.mail_list);
     InboxAdapter adapter=new InboxAdapter(this,YourArrayList);
    list.setAdapter(adapter);
}
于 2012-05-14T13:55:12.220 回答