Android 带集合的小部件 (ListView) 不显示项目
Android Widget with collection (ListView) not displaying items
我正在尝试为我的应用程序做一个简单的小部件，它使用 ListView 在小部件上显示来自 API 的数据，但列表是空的，即使日志显示数据已成功下载。
显示空白 listView，其中没有数据。没有显示错误。这是什么原因？
我在尝试解决这个问题时使用的资源：
官方文档 - https://developer.android.com/guide/topics/appwidgets#collections
类似问题 - How to use listview in a widget?
我的 AppWidgetProvider
public class Widget extends AppWidgetProvider {
RemoteViews views;
void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
int appWidgetId) {
CharSequence widgetText = context.getString(R.string.appwidget_text);
// Construct the RemoteViews object
views = new RemoteViews(context.getPackageName(), R.layout.my_widget);
views.setTextViewText(R.id.appwidget_text, widgetText);
// Instruct the widget manager to update the widget
appWidgetManager.updateAppWidget(appWidgetId, views);
}
@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
// There may be multiple widgets active, so update all of them
for (int appWidgetId : appWidgetIds) {
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.my_widget);
Intent intent = new Intent(context, WidgetService.class);
remoteViews.setRemoteAdapter(R.id.appwidget_list_view, intent);
appWidgetManager.updateAppWidget(appWidgetId, remoteViews);
}
}
WidgetFactory 和 WidgetService
public class WidgetFactory implements RemoteViewsService.RemoteViewsFactory{
final Context context;
List<SimpleCoin> list;
List<Coin> coinList;
public WidgetFactory(Context context, Intent intent) {
this.context = context;
}
@Override
public void onCreate() {
//get data from database
CoinDatabase coinDatabase = CoinDatabase.buildDatabase(context);
list = coinDatabase.coinDao().getAllSimpleCoinsNonLive();
coinList = new ArrayList<>();
}
@Override
public void onDataSetChanged() {
//based on data from database download content (JSON)
if(list != null) {
Log.d("Widget", "Coin size -> " + list.size());
StringBuilder id = new StringBuilder("id=" + list.get(0).getId());
for (int j = 0; j < list.size(); j++) {
id.append(",");
id.append(list.get(j).getId());
}
String finalUrl = URL + id.toString() + API_KEY;
Observable.fromCallable(() -> {
HttpURLConnection connection = null;
BufferedReader reader = null;
java.net.URL url1 = new URL(finalUrl);
connection = (HttpURLConnection) url1.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuilder buffer = new StringBuilder();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line).append("\n");
}
connection.disconnect();
reader.close();
return buffer.toString();
}).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe(new Observer<String>() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onNext(@NonNull String s) {
if (s != null) {
try {
//Create new coin and update list of coins
JSONObject object = new JSONObject(s);
for (int i = 0; i < list.size(); i++) {
JSONObject jsonObject = object.getJSONObject("data").getJSONObject(String.valueOf(list.get(i).getId()));
Log.d("Widget", "Coin -> " + jsonObject.getString("name") + jsonObject.getJSONObject("quote").getJSONObject("USD").getDouble("price") + jsonObject.getJSONObject("quote").getJSONObject("USD").getDouble("percent_change_7d"));
Coin coin = new Coin(jsonObject.getString("name"), jsonObject.getJSONObject("quote").getJSONObject("USD").getDouble("price"), jsonObject.getJSONObject("quote").getJSONObject("USD").getDouble("percent_change_7d"), false);
coinList.add(coin);
getViewAt(i);
}
} catch (JSONException e) {
Log.d("Widget", "Coin -> " + e.toString());
e.printStackTrace();
}
}
}
@Override
public void onError(@NonNull Throwable e) {
}
@Override
public void onComplete() {
}
});
}
}
@Override
public void onDestroy() {}
@Override
public int getCount() {
return list.size();
}
@Override
public RemoteViews getViewAt(int i) {
//Set ListData based on coinList
Log.d("Widget", "Coin size getViewAt -> " + list.size() + "item num ->" + i);
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.my_widget_list_item);
if(coinList != null)
if(coinList.size() > i) {
Log.d("Widget", "Coin position added" + coinList.get(i).getName());
remoteViews.setTextViewText(R.id.widgetItemTaskNameLabel, coinList.get(i).getName());
}
return remoteViews;
}
@Override
public RemoteViews getLoadingView() {
return null;
}
@Override
public int getViewTypeCount() {
return 1;
}
@Override
public long getItemId(int i) {
return i;
}
@Override
public boolean hasStableIds() {
return true;
}
}
public class WidgetService extends RemoteViewsService {
@Override
public RemoteViewsFactory onGetViewFactory(Intent intent) {
return new WidgetFactory(this.getApplicationContext(), intent);
}
}
这是我的日志：
D/Widget: Coin size getViewAt -> 1 item num ->0
D/Widget: Coin size getViewAt -> 1 item num ->0
D/Widget: Coin -> testCoin0.00.0
D/Widget: Coin size getViewAt -> 1 item num ->0
D/Widget: Coin position added testCoin
my_widget.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:tools="http://schemas.android.com/tools"
android:background="@color/colorPrimary"
android:padding="@dimen/widget_margin">
<TextView
android:id="@+id/appwidget_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_margin="8dp"
android:background="@color/colorPrimary"
android:contentDescription="@string/appwidget_text"
android:text="@string/appwidget_text"
android:textColor="#ffffff"
android:textSize="24sp"
android:textStyle="bold|italic" />
<ListView
android:id="@+id/appwidget_list_view"
android:layout_width="match_parent"
android:layout_margin="8dp"
tools:listitem="@layout/my_widget_list_item"
android:layout_height="wrap_content"
android:background="@color/colorAccent"
android:layout_below="@id/appwidget_text">
</ListView>
</RelativeLayout>
my_widget_list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:paddingLeft="@dimen/widget_listview_padding_x"
android:paddingRight="@dimen/widget_listview_padding_x"
android:paddingStart="@dimen/widget_listview_padding_x"
android:paddingEnd="@dimen/widget_listview_padding_x"
android:minHeight="@dimen/widget_listview_item_height"
android:weightSum="2"
android:layout_height="wrap_content">
<TextView
android:id="@+id/widgetItemTaskNameLabel"
android:layout_width="0dp"
android:gravity="start"
android:layout_weight="1"
android:textColor="@color/colorPrimary"
android:layout_gravity="center_vertical"
android:layout_height="wrap_content" />
</LinearLayout>
我发现了我的错误，原来我的 API 调用不应该是异步的，因为正如文档所说：
public void onDataSetChanged() ->
You can do heaving lifting in here, synchronously. For example, if you need to process an image, fetch something from the network, etc., it is ok to do it here, synchronously. The widget will remain in its current state while work is being done here, so you don't need to worry about locking up the widget.
所以从异步调用中获取我的数据是数据未显示的原因
我正在尝试为我的应用程序做一个简单的小部件，它使用 ListView 在小部件上显示来自 API 的数据，但列表是空的，即使日志显示数据已成功下载。 显示空白 listView，其中没有数据。没有显示错误。这是什么原因？
我在尝试解决这个问题时使用的资源：
官方文档 - https://developer.android.com/guide/topics/appwidgets#collections
类似问题 - How to use listview in a widget?
我的 AppWidgetProvider
public class Widget extends AppWidgetProvider {
RemoteViews views;
void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
int appWidgetId) {
CharSequence widgetText = context.getString(R.string.appwidget_text);
// Construct the RemoteViews object
views = new RemoteViews(context.getPackageName(), R.layout.my_widget);
views.setTextViewText(R.id.appwidget_text, widgetText);
// Instruct the widget manager to update the widget
appWidgetManager.updateAppWidget(appWidgetId, views);
}
@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
// There may be multiple widgets active, so update all of them
for (int appWidgetId : appWidgetIds) {
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.my_widget);
Intent intent = new Intent(context, WidgetService.class);
remoteViews.setRemoteAdapter(R.id.appwidget_list_view, intent);
appWidgetManager.updateAppWidget(appWidgetId, remoteViews);
}
}
WidgetFactory 和 WidgetService
public class WidgetFactory implements RemoteViewsService.RemoteViewsFactory{
final Context context;
List<SimpleCoin> list;
List<Coin> coinList;
public WidgetFactory(Context context, Intent intent) {
this.context = context;
}
@Override
public void onCreate() {
//get data from database
CoinDatabase coinDatabase = CoinDatabase.buildDatabase(context);
list = coinDatabase.coinDao().getAllSimpleCoinsNonLive();
coinList = new ArrayList<>();
}
@Override
public void onDataSetChanged() {
//based on data from database download content (JSON)
if(list != null) {
Log.d("Widget", "Coin size -> " + list.size());
StringBuilder id = new StringBuilder("id=" + list.get(0).getId());
for (int j = 0; j < list.size(); j++) {
id.append(",");
id.append(list.get(j).getId());
}
String finalUrl = URL + id.toString() + API_KEY;
Observable.fromCallable(() -> {
HttpURLConnection connection = null;
BufferedReader reader = null;
java.net.URL url1 = new URL(finalUrl);
connection = (HttpURLConnection) url1.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuilder buffer = new StringBuilder();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line).append("\n");
}
connection.disconnect();
reader.close();
return buffer.toString();
}).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe(new Observer<String>() {
@Override
public void onSubscribe(@NonNull Disposable d) {
}
@Override
public void onNext(@NonNull String s) {
if (s != null) {
try {
//Create new coin and update list of coins
JSONObject object = new JSONObject(s);
for (int i = 0; i < list.size(); i++) {
JSONObject jsonObject = object.getJSONObject("data").getJSONObject(String.valueOf(list.get(i).getId()));
Log.d("Widget", "Coin -> " + jsonObject.getString("name") + jsonObject.getJSONObject("quote").getJSONObject("USD").getDouble("price") + jsonObject.getJSONObject("quote").getJSONObject("USD").getDouble("percent_change_7d"));
Coin coin = new Coin(jsonObject.getString("name"), jsonObject.getJSONObject("quote").getJSONObject("USD").getDouble("price"), jsonObject.getJSONObject("quote").getJSONObject("USD").getDouble("percent_change_7d"), false);
coinList.add(coin);
getViewAt(i);
}
} catch (JSONException e) {
Log.d("Widget", "Coin -> " + e.toString());
e.printStackTrace();
}
}
}
@Override
public void onError(@NonNull Throwable e) {
}
@Override
public void onComplete() {
}
});
}
}
@Override
public void onDestroy() {}
@Override
public int getCount() {
return list.size();
}
@Override
public RemoteViews getViewAt(int i) {
//Set ListData based on coinList
Log.d("Widget", "Coin size getViewAt -> " + list.size() + "item num ->" + i);
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.my_widget_list_item);
if(coinList != null)
if(coinList.size() > i) {
Log.d("Widget", "Coin position added" + coinList.get(i).getName());
remoteViews.setTextViewText(R.id.widgetItemTaskNameLabel, coinList.get(i).getName());
}
return remoteViews;
}
@Override
public RemoteViews getLoadingView() {
return null;
}
@Override
public int getViewTypeCount() {
return 1;
}
@Override
public long getItemId(int i) {
return i;
}
@Override
public boolean hasStableIds() {
return true;
}
}
public class WidgetService extends RemoteViewsService {
@Override
public RemoteViewsFactory onGetViewFactory(Intent intent) {
return new WidgetFactory(this.getApplicationContext(), intent);
}
}
这是我的日志：
D/Widget: Coin size getViewAt -> 1 item num ->0
D/Widget: Coin size getViewAt -> 1 item num ->0
D/Widget: Coin -> testCoin0.00.0
D/Widget: Coin size getViewAt -> 1 item num ->0
D/Widget: Coin position added testCoin
my_widget.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:tools="http://schemas.android.com/tools"
android:background="@color/colorPrimary"
android:padding="@dimen/widget_margin">
<TextView
android:id="@+id/appwidget_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_margin="8dp"
android:background="@color/colorPrimary"
android:contentDescription="@string/appwidget_text"
android:text="@string/appwidget_text"
android:textColor="#ffffff"
android:textSize="24sp"
android:textStyle="bold|italic" />
<ListView
android:id="@+id/appwidget_list_view"
android:layout_width="match_parent"
android:layout_margin="8dp"
tools:listitem="@layout/my_widget_list_item"
android:layout_height="wrap_content"
android:background="@color/colorAccent"
android:layout_below="@id/appwidget_text">
</ListView>
</RelativeLayout>
my_widget_list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:paddingLeft="@dimen/widget_listview_padding_x"
android:paddingRight="@dimen/widget_listview_padding_x"
android:paddingStart="@dimen/widget_listview_padding_x"
android:paddingEnd="@dimen/widget_listview_padding_x"
android:minHeight="@dimen/widget_listview_item_height"
android:weightSum="2"
android:layout_height="wrap_content">
<TextView
android:id="@+id/widgetItemTaskNameLabel"
android:layout_width="0dp"
android:gravity="start"
android:layout_weight="1"
android:textColor="@color/colorPrimary"
android:layout_gravity="center_vertical"
android:layout_height="wrap_content" />
</LinearLayout>
我发现了我的错误，原来我的 API 调用不应该是异步的，因为正如文档所说：
public void onDataSetChanged() -> You can do heaving lifting in here, synchronously. For example, if you need to process an image, fetch something from the network, etc., it is ok to do it here, synchronously. The widget will remain in its current state while work is being done here, so you don't need to worry about locking up the widget.
所以从异步调用中获取我的数据是数据未显示的原因