我正在尝试实现从数据库获取数据并显示它的SimpleCursorAdapter。直到现在我使用的ArrayAdapter完美无缺。
但是因为我更改了CursorAdapter的代码，所以它在片段上没有显示任何内容。
Cursor将数据存储在ListView。
这里是片段类（虽然有很多代码）：
public class ForecastFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor>
{
//ArrayAdapter<String> mForecastAdapter;
/**Change to cursor Adapter*/
SimpleCursorAdapter mForecastAdapter;
String Cityname;
/*Loader Id**/
private String mLocation;
private final static int FORECAST_LOADER = 0;
// Projection columns
private static final String[] FORECAST_COLUMNS = {
WeatherEntry.TABLE_NAME + "." + WeatherEntry._ID,
WeatherEntry.COLUMN_DATE,
WeatherEntry.COLUMN_SHORT_DESC,
WeatherEntry.COLUMN_MAX_TEMP,
WeatherEntry.COLUMN_MIN_TEMP,
WeatherContract.LocationEntry.COLUMN_LOCATION_SETTING,
WeatherEntry.COLUMN_WEATHER_ID,
WeatherContract.LocationEntry.COLUMN_COORD_LAT,
WeatherContract.LocationEntry.COLUMN_COORD_LONG
};
// Indices for forecast column
static final int COL_WEATHER_ID = 0;
static final int COL_WEATHER_DATE=1;
static final int COL_WEATHER_DESC=2;
static final int COL_WEATHER_MAX_TEMP=3;
static final int COL_WEATHER_MIN_TEMP = 4;
static final int COL_LOCATION_SETTING =5;
static final int COL_WEATHER_CONDITION_ID=6;
static final int COL_COORD_LAT =7;
static final int COL_COORD_LONG =8;
public ForecastFragment(){
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
getLoaderManager().initLoader(FORECAST_LOADER,null,this);
}
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.forecastfragment,menu);
}
private void updateWeather(){
FetchWeatherTask weatherTask = new FetchWeatherTask(getContext());
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
String location = prefs.getString(getString(R.string.pref_location_key),getString(R.string.pref_location_default));
weatherTask.execute(location);
// weatherTask.execute("201014");
//return true;
}
@Override
public void onStart() {
super.onStart();
updateWeather();
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id=item.getItemId();
if(id==R.id.action_refresh)
{
updateWeather();
}
return super.onOptionsItemSelected(item);
}
@Override
public String toString() {
return super.toString();
}
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args)
{
/* String locationSetting = Utility.getPreferredLocation(getActivity());
//Sort Order ; ASC(Date)
String sortOrder = WeatherEntry.COLUMN_DATE + "ASC";
Uri weatherForLocationUri = WeatherEntry.buildWeatherLocationWithStartDate(locationSetting, System.currentTimeMillis());*/
String startDate = WeatherContract.getDbDateString(new java.util.Date());
// Sort order: Ascending, by date
String sortOrder = WeatherEntry.COLUMN_DATE + " ASC";
mLocation = Utility.getPreferredLocation(getActivity());
Uri weatherForLocationUri = WeatherEntry.buildWeatherLocationWithStartDate(mLocation, System.currentTimeMillis()/*startDate*/);
return new CursorLoader(getActivity()
,weatherForLocationUri
,FORECAST_COLUMNS
,null
,null
,sortOrder);
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
mForecastAdapter.swapCursor(data);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
mForecastAdapter.swapCursor(null);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView =inflater.inflate(R.layout.fragment_main, container, false);
String [] forecastArray = {
"today-sunny-88/63",
"tomorrow-foggy-70/40",
"weds-cloudy-72/63",
"thurs-asteroids-75/65",
"fri-heavy rain-65/56",
"sat-day off - 55/55",
"sun - i dont know- 80/68"
};
List<String> weekForecast = new ArrayList<String>(Arrays.asList(forecastArray));
/* //ArrayAdapter<String>
mForecastAdapter = new ArrayAdapter<String>(
//The current context (parent activity)
getActivity(),
// ID of list item layout
R.layout.list_item_forecast,
// ID of text view
R.id.list_item_forecast_textview,
// list of data
weekForecast
);*/
mForecastAdapter = new SimpleCursorAdapter(
//The current context (parent activity)
getActivity(),
// ID of list item layout
R.layout.list_item_forecast,
null,
//column nmaes
new String[]{
WeatherEntry.COLUMN_DATE,
WeatherEntry.COLUMN_SHORT_DESC,
WeatherEntry.COLUMN_MAX_TEMP,
WeatherEntry.COLUMN_MIN_TEMP},
// ID of text view
new int[]{
R.id.list_item_date_textview,
R.id.list_item_forecast_textview,
R.id.list_item_high_textview,
R.id.list_item_low_textview
},0
);
// forecast bind
mForecastAdapter.setViewBinder(new SimpleCursorAdapter.ViewBinder() {
@Override
public boolean setViewValue(View view, Cursor cursor, int columnIndex) {
boolean isMetric = Utility.isMetric(getActivity());
switch (columnIndex) {
case COL_WEATHER_MAX_TEMP:
case COL_WEATHER_MIN_TEMP:
// we have to do some formatting and possibly a conversion
((TextView) view).setText(Utility.formatTemperature(cursor.getDouble(columnIndex), isMetric));
return true;
case COL_WEATHER_DATE:
String dateString = cursor.getString(columnIndex);
TextView dateView = (TextView) view;
dateView.setText(Utility.formatDate(dateString));
return true;
}
// If return false, 2 types of binding will occur
// 1: view is a TextView, SimpleCursorAdapter#setViewText(TextView, String) is called
// 2: view is a ImageView, SimpleCursorAdapter#setViewImage(ImageView v, String value) is called
return false;
}
});
ListView listView = (ListView) rootView.findViewById(R.id.listview_forecast);
listView.setAdapter(mForecastAdapter);
// for clicking
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long l)
{
/* String forecast = mForecastAdapter.getItem(position);
// Toast.makeText(getActivity(),forecast, Toast.LENGTH_SHORT).show();
Intent intent = new Intent(getActivity(),DetailActivity.class)
.putExtra(Intent.EXTRA_TEXT,forecast);
startActivity(intent);*/
}
});
return rootView;
}
}
这里是list_item_forecast.xml：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:orientation="horizontal"
>
<TextView
android:id="@+id/list_item_date_textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:text="TextView" />
<TextView
android:id="@+id/list_item_empty"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="0.08"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:text="-" />
<TextView
android:id="@+id/list_item_forecast_textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:layout_weight="0.08"
/>
<TextView
android:id="@+id/list_item_emptyview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:layout_weight="0.08"
android:text="-" />
<TextView
android:id="@+id/list_item_high_textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:layout_weight="0.08"
/>
<TextView
android:id="@+id/list_item_slash"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:layout_weight="0.08"
android:text="/" />
<TextView
android:id="@+id/list_item_low_textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:layout_weight="0.08"
/>
</LinearLayout>
没有错误。 Logcat显示已从数据库中正确获取数据。
数据库和其他功能正常工作。我只是看不到片段上的任何数据。
有人能帮助我吗？
答案 0 :(得分：0)
也许你和我犯了同样的错误。片段默认textColor为白色，图像的可见性不可见。因此，您应将文本颜色设置为黑色，并将可见性属性设置为可见;