Question

我一直试图弄清楚这件事发生了一段时间，也许我已经盯着它看了太久......我觉得它很简单。

这是我的ListActivity类

    public class ResultsListActivity extends ListActivity {
    private ArrayList<Result> results = new ArrayList<Result>();
    private ListView list;


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.sp_history);
        //set up list
        list = new ListView(this);

    }

    @Override
    protected void onResume()
    {
        super.onResume();
        results = openAndQueryDatabase();
        displayResultList();
    }
    private void displayResultList() {


        list.setAdapter(new HistoryArrayAdapter(this.getBaseContext(), results));

    }
    private ArrayList<Result> openAndQueryDatabase() {
        DatabaseHandler dbh = new DatabaseHandler(getBaseContext());
        ArrayList<Result> toReturn = dbh.getAllResults();
        return toReturn;

    }//open and query database

    public int getCount() {
        return null == results ? 0 : results.size();
    }

    }

这是我的ListAdapterClass

    public class HistoryArrayAdapter extends ArrayAdapter<Result> {


  private final Context context;
  private final ArrayList<Result> values;
  private int layoutId;

  public HistoryArrayAdapter(Context context, ArrayList<Result> results) {
    super(context, R.layout.history_row, results);
    this.context = context;
    this.layoutId = R.layout.history_row;
    this.values = results;
  }

  @Override
    public int getCount() {
        return values.size();// more than zero
    }

  @Override
    public Result getItem(int position) {

        return values.get(position);// may be in your case
    }

  @Override
  public View getView(int position, View convertView, ViewGroup parent) {
      if(convertView==null)
      {
                      // inflate the layout
                      LayoutInflater inflater = ((Activity) context).getLayoutInflater();
                      convertView = inflater.inflate(layoutId, parent, false);
      }// if convertView == null

    //set up our views
    TextView uploadSpeed = (TextView) convertView.findViewById(R.id.upload_speed_history);
    TextView downloadSpeed = (TextView) convertView.findViewById(R.id.download_speed_history);
    TextView pingTime = (TextView) convertView.findViewById(R.id.ping_history_text);
    TextView networkName = (TextView) convertView.findViewById(R.id.history_network_name);
    TextView dateTime = (TextView) convertView.findViewById(R.id.history_dateTime);
    ImageView imageView = (ImageView) convertView.findViewById(R.id.history_connection);

    //set up our values
    Result row = values.get(position);
    uploadSpeed.setText(row.getUpload());
    downloadSpeed.setText(row.getDownload());
    pingTime.setText(row.getPingTime());
    networkName.setText(row.getNetworkName());
    dateTime.setText(row.getDateTime());
    if(row.getNetworkType() == "NETWORK_WIFI")
        imageView.setImageResource(R.drawable.ico_wifi);
    else
        imageView.setImageResource(R.drawable.ico_cell);

    return convertView;
  }//getView

     }

这是ListView的.xml

     <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
   android:orientation="vertical">

<ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:divider="#b5b5b5"
    android:dividerHeight="1dp" />

 </LinearLayout>

这是行布局

     <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:orientation="vertical" >

<RelativeLayout
    android:id="@+id/realtive_line_1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" >

    <TextView
        android:id="@+id/history_network_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="26dp"
        android:layout_toRightOf="@+id/imageView1"
        android:text="TextView" />

    <ImageView
        android:id="@+id/history_connection"
        android:layout_width="20dip"
        android:layout_height="20dip"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft = "20dip"
        android:layout_marginTop = "5dip"
        android:src="@drawable/ico_wifi" />

    <TextView
        android:id="@+id/history_dateTime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="65dp"
        android:layout_below="@+id/network_name"
        android:text="2013-08-15 12:35:00 PM" 
        android:textSize="10sp" />

</RelativeLayout>

<RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" 
    android:layout_below="@+id/realtive_line_1"
    >

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="15dip"
        android:layout_height="15dip"
        android:layout_alignParentLeft="true"
        android:layout_centerVertical="true"
        android:layout_marginLeft="23dp"
        android:layout_marginTop = "15dip"
        android:src="@drawable/ico_ping" />

    <TextView
        android:id="@+id/ping_history_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_marginLeft="25dp"
        android:layout_toRightOf="@+id/imageView2"
        android:text="30 ms"
        android:textSize = "15sp"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <ImageView
        android:id="@+id/results_icon_up"
        android:layout_width="20dip"
        android:layout_height="20dip"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:src="@drawable/ico_up"
        android:layout_marginRight = "40dip" />

    <ImageView
        android:id="@+id/results_icon_down"
        android:layout_width="20dip"
        android:layout_height="20dip"
        android:layout_alignParentRight="true"
        android:layout_marginTop="5dip"
        android:layout_below ="@+id/results_icon_up"
        android:src="@drawable/ico_down"
        android:layout_marginRight = "40dip" />

    <TextView
        android:id="@+id/upload_speed_history"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/results_icon_down"
        android:layout_marginRight="15dp"
        android:layout_toLeftOf="@+id/results_icon_up"
        android:text="4.26 Mbps"
        android:textAppearance="?android:attr/textAppearanceSmall" />

    <TextView
        android:id="@+id/download_speed_history"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/upload_speed_history"
        android:layout_alignTop="@+id/results_icon_down"
        android:text="24.56 Mbps"
        android:textAppearance="?android:attr/textAppearanceSmall" />

</RelativeLayout>

<ImageView
    android:id="@+id/imageView3"
    android:layout_width="20dip"
    android:layout_height="20dip"
    android:layout_alignParentRight ="true"
    android:layout_centerVertical="true"
    android:src="@drawable/arrow" />

 </RelativeLayout>

我知道的事情......我确实有结果。我可以在调试器中看到它并且它们填充得很好。我知道我有一些看似不必要的方法，有一些工作要做，以确保应用程序在填充列表之前不在进程的中间。

Answer 1

更改您的onCreate()，如下所示

 @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.sp_history);
        //set up list
        list = getListView();

    }

Answer 2

如果您已声明正在使用异步调用来获取数据库结果...即使在调试时您获得结果，但实际运行时可能会在设置适配器后获得结果在以下行中，适配器中results的长度为0，因此您的getView()没有收到回调。

可以有一个自定义Listener，它将在获取结果时获得回调，然后您可以将适配器设置为列表视图，或者另一个解决方案可能是保留适配器的实例然后添加使用Adapter.add()方法将获取的结果发送到适配器，然后调用Adapter.notifyDataSetChanged()方法。

修改： - 当您使用ListActivity时，无需创建新的ListView实例。只需调用getListView()方法即可获得上述回答者建议的ListView实例。

自定义ListAdapter从不调用GetView

2 个答案: