我不知道错误在哪里，logcat没有显示任何内容
应用程序无法启动，我只是收到应用程序停止了。它不会打开。
这个片段存在问题。我试图通过JOSN从免费天气API收到的数据填充listview。我使用自定义对象HourlyForecast，其中包含有关温度，降水量，天气图标和时间的数据。
public class Tab3 extends Fragment {
Typeface weatherFont;
TextView timeField;
TextView precipitationField;
TextView temperatureField;
TextView weatherIcon;
ListView listView;
MyAdapter adapter;
ArrayList<HourlyForecast> hourlyForecastArrayList = new ArrayList<>();
Handler handler;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
weatherFont = Typeface.createFromAsset(getActivity().getAssets(), "fonts/weather.ttf");
updateWeatherData("Belgrade");
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.tab3, container, false);
timeField = (TextView) v.findViewById(R.id.time_hourly_field);
weatherIcon = (TextView) v.findViewById(R.id.weather_hourly_icon);
precipitationField = (TextView) v.findViewById(R.id.precipitation_hourly_field);
temperatureField = (TextView) v.findViewById(R.id.temperature_hourly_field);
weatherIcon.setTypeface(weatherFont);
listView = (ListView) v.findViewById(R.id.my_list);
adapter = new MyAdapter(getActivity(), hourlyForecastArrayList);
listView.setAdapter(adapter);
return v;
}
private void updateWeatherData(final String city) {
new Thread() {
public void run() {
final JSONObject json = RemoteFetch.getJSON(getActivity(), city, 2);
if (json == null) {
handler.post(new Runnable() {
public void run() {
Toast.makeText(getActivity(),
getActivity().getString(R.string.place_not_found),
Toast.LENGTH_LONG).show();
}
});
} else {
handler.post(new Runnable() {
public void run() {
renderWeather(json);
}
});
}
}
}.start();
}
private void renderWeather(JSONObject json) {
try {
JSONArray listObjects = json.getJSONArray("list");
for (int i = 0; i < listObjects.length(); i++) {
DateFormat df = DateFormat.getDateTimeInstance();
String time = df.format(new Date(json.getLong("dt") * 1000));
String precipitation = listObjects.getJSONObject(i).getString("rain");
String temperature = listObjects.getJSONObject(i).getJSONObject("main").getString("temp");
int weatherIconId = listObjects.getJSONObject(i).getJSONArray("weather").getInt(0);
HourlyForecast hourlyForecast = new HourlyForecast(time, precipitation, temperature, weatherIconId);
hourlyForecastArrayList.add(hourlyForecast);
}
} catch (Exception e) {
Log.e("SimpleWeather", "One or more fields not found in the JSON data");
Toast.makeText(getActivity(), "No JSON data found", Toast.LENGTH_LONG).show();
}
}
private void setWeatherIcon(int actualId, int day_night) {
int id = actualId / 100;
String icon = "";
if (actualId == 800) {
long currentTime = new Date().getTime();
if (day_night == 1) {
icon = getActivity().getString(R.string.weather_sunny);
} else if (day_night == 2) {
icon = getActivity().getString(R.string.weather_clear_night);
}
} else {
switch (id) {
case 2:
icon = getActivity().getString(R.string.weather_thunder);
break;
case 3:
icon = getActivity().getString(R.string.weather_drizzle);
break;
case 7:
icon = getActivity().getString(R.string.weather_foggy);
break;
case 8:
icon = getActivity().getString(R.string.weather_cloudy);
break;
case 6:
icon = getActivity().getString(R.string.weather_snowy);
break;
case 5:
icon = getActivity().getString(R.string.weather_rainy);
break;
}
}
weatherIcon.setText(icon);
}
class MyAdapter extends ArrayAdapter<HourlyForecast> {
ArrayList<HourlyForecast> hourlyForecastArrayListInAdapter = new ArrayList<>();
public MyAdapter(Context context, ArrayList<HourlyForecast> hourlyForecasts) {
super(context, R.layout.row_hourly);
hourlyForecastArrayListInAdapter = hourlyForecasts;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = getActivity().getLayoutInflater();
View rowView = inflater.inflate(R.layout.row_hourly, null, true);
HourlyForecast forecastInAdapter = hourlyForecastArrayListInAdapter.get(position);
timeField.setText(forecastInAdapter.getTime());
precipitationField.setText(forecastInAdapter.getPrecipitation());
temperatureField.setText(forecastInAdapter.getTemperature());
setWeatherIcon(forecastInAdapter.getWeatherIconId(), 1);
return rowView;
}
}
}
这是一个logcat
java.lang.NullPointerException
at com.slobx.slobodan.weathermob.Tab3.onCreateView(Tab3.java:61)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:490)
at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:163)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1105)
at android.support.v4.view.ViewPager.populate(ViewPager.java:951)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1473)
at android.view.View.measure(View.java:15172)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:833)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148)
at android.view.View.measure(View.java:15172)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1848)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1100)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1273)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4212)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
at android.view.Choreographer.doCallbacks(Choreographer.java:555)
at android.view.Choreographer.doFrame(Choreographer.java:525)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
这可能来自NullPointerException无法实例化TextView。
检查您的布局R.layout.tab3，确保ID TextView的{{1}}确实存在。