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Ich bekomme immer einen leeren Bildschirm nach dem Ausführen des Codes unter. Ich habe einen benutzerdefinierten Array-Adapter und eine benutzerdefinierte Klasse erstellt, aber es gab keinen leeren Bildschirm wenn Ich habe eine Array-Liste verwendet, um Elemente in einer Listenansicht anzuzeigen. aber jetzt möchte ich Parsing testen von JSON-Daten unter Verwendung von jetzt ist es ein leerer Bildschirm geben, warum bitte helfen hierLeere Bildschirmausgabe beim Analysieren von Daten aus Json-Code aus einer Website extrahiert Api
import android.util.Log;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
/**
* Helper methods related to requesting and receiving earthquake data from USGS.
*/
public final class QueryUtils {
/** Sample JSON response for a USGS query */
private static final String SAMPLE_JSON_RESPONSE = "{\"type\":\"FeatureCollection\",\"metadata\":{\"generated\":1462295443000,\"url\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&starttime=2016-01-01&endtime=2016-01-31&minmag=6&limit=10\",\"title\":\"USGS Earthquakes\",\"status\":200,\"api\":\"1.5.2\",\"limit\":10,\"offset\":1,\"count\":10},\"features\":[{\"type\":\"Feature\",\"properties\":{\"mag\":7.2,\"place\":\"88km N of Yelizovo, Russia\",\"time\":1454124312220,\"updated\":1460674294040,\"tz\":720,\"url\":\"http://earthquake.usgs.gov/earthquakes/eventpage/us20004vvx\",\"detail\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us20004vvx&format=geojson\",\"felt\":2,\"cdi\":3.4,\"mmi\":5.82,\"alert\":\"green\",\"status\":\"reviewed\",\"tsunami\":1,\"sig\":798,\"net\":\"us\",\"code\":\"20004vvx\",\"ids\":\",at00o1qxho,pt16030050,us20004vvx,gcmt20160130032510,\",\"sources\":\",at,pt,us,gcmt,\",\"types\":\",cap,dyfi,finite-fault,general-link,general-text,geoserve,impact-link,impact-text,losspager,moment-tensor,nearby-cities,origin,phase-data,shakemap,tectonic-summary,\",\"nst\":null,\"dmin\":0.958,\"rms\":1.19,\"gap\":17,\"magType\":\"mww\",\"type\":\"earthquake\",\"title\":\"M 7.2 - 88km N of Yelizovo, Russia\"},\"geometry\":{\"type\":\"Point\",\"coordinates\":[158.5463,53.9776,177]},\"id\":\"us20004vvx\"},\n" +
"{\"type\":\"Feature\",\"properties\":{\"mag\":6.1,\"place\":\"94km SSE of Taron, Papua New Guinea\",\"time\":1453777820750,\"updated\":1460156775040,\"tz\":600,\"url\":\"http://earthquake.usgs.gov/earthquakes/eventpage/us20004uks\",\"detail\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us20004uks&format=geojson\",\"felt\":null,\"cdi\":null,\"mmi\":4.1,\"alert\":\"green\",\"status\":\"reviewed\",\"tsunami\":1,\"sig\":572,\"net\":\"us\",\"code\":\"20004uks\",\"ids\":\",us20004uks,gcmt20160126031023,\",\"sources\":\",us,gcmt,\",\"types\":\",cap,geoserve,losspager,moment-tensor,nearby-cities,origin,phase-data,shakemap,tectonic-summary,\",\"nst\":null,\"dmin\":1.537,\"rms\":0.74,\"gap\":25,\"magType\":\"mww\",\"type\":\"earthquake\",\"title\":\"M 6.1 - 94km SSE of Taron, Papua New Guinea\"},\"geometry\":{\"type\":\"Point\",\"coordinates\":[153.2454,-5.2952,26]},\"id\":\"us20004uks\"},\n" +
"{\"type\":\"Feature\",\"properties\":{\"mag\":6.3,\"place\":\"50km NNE of Al Hoceima, Morocco\",\"time\":1453695722730,\"updated\":1460156773040,\"tz\":0,\"url\":\"http://earthquake.usgs.gov/earthquakes/eventpage/us10004gy9\",\"detail\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us10004gy9&format=geojson\",\"felt\":117,\"cdi\":7.2,\"mmi\":5.28,\"alert\":\"green\",\"status\":\"reviewed\",\"tsunami\":0,\"sig\":695,\"net\":\"us\",\"code\":\"10004gy9\",\"ids\":\",us10004gy9,gcmt20160125042203,\",\"sources\":\",us,gcmt,\",\"types\":\",cap,dyfi,geoserve,impact-text,losspager,moment-tensor,nearby-cities,origin,phase-data,shakemap,tectonic-summary,\",\"nst\":null,\"dmin\":2.201,\"rms\":0.92,\"gap\":20,\"magType\":\"mww\",\"type\":\"earthquake\",\"title\":\"M 6.3 - 50km NNE of Al Hoceima, Morocco\"},\"geometry\":{\"type\":\"Point\",\"coordinates\":[-3.6818,35.6493,12]},\"id\":\"us10004gy9\"},\n" +
"{\"type\":\"Feature\",\"properties\":{\"mag\":7.1,\"place\":\"86km E of Old Iliamna, Alaska\",\"time\":1453631430230,\"updated\":1460156770040,\"tz\":-540,\"url\":\"http://earthquake.usgs.gov/earthquakes/eventpage/us10004gqp\",\"detail\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us10004gqp&format=geojson\",\"felt\":1816,\"cdi\":7.2,\"mmi\":6.6,\"alert\":\"green\",\"status\":\"reviewed\",\"tsunami\":1,\"sig\":1496,\"net\":\"us\",\"code\":\"10004gqp\",\"ids\":\",at00o1gd6r,us10004gqp,ak12496371,gcmt20160124103030,\",\"sources\":\",at,us,ak,gcmt,\",\"types\":\",cap,dyfi,finite-fault,general-link,general-text,geoserve,impact-link,impact-text,losspager,moment-tensor,nearby-cities,origin,phase-data,shakemap,tectonic-summary,trump-origin,\",\"nst\":null,\"dmin\":0.72,\"rms\":2.11,\"gap\":19,\"magType\":\"mww\",\"type\":\"earthquake\",\"title\":\"M 7.1 - 86km E of Old Iliamna, Alaska\"},\"geometry\":{\"type\":\"Point\",\"coordinates\":[-153.4051,59.6363,129]},\"id\":\"us10004gqp\"},\n" +
"{\"type\":\"Feature\",\"properties\":{\"mag\":6.6,\"place\":\"215km SW of Tomatlan, Mexico\",\"time\":1453399617650,\"updated\":1459963829040,\"tz\":-420,\"url\":\"http://earthquake.usgs.gov/earthquakes/eventpage/us10004g4l\",\"detail\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us10004g4l&format=geojson\",\"felt\":11,\"cdi\":2.7,\"mmi\":3.92,\"alert\":\"green\",\"status\":\"reviewed\",\"tsunami\":1,\"sig\":673,\"net\":\"us\",\"code\":\"10004g4l\",\"ids\":\",at00o1bebo,pt16021050,us10004g4l,gcmt20160121180659,\",\"sources\":\",at,pt,us,gcmt,\",\"types\":\",cap,dyfi,geoserve,impact-link,impact-text,losspager,moment-tensor,nearby-cities,origin,phase-data,shakemap,tectonic-summary,\",\"nst\":null,\"dmin\":2.413,\"rms\":0.98,\"gap\":74,\"magType\":\"mww\",\"type\":\"earthquake\",\"title\":\"M 6.6 - 215km SW of Tomatlan, Mexico\"},\"geometry\":{\"type\":\"Point\",\"coordinates\":[-106.9337,18.8239,10]},\"id\":\"us10004g4l\"},\n" +
"{\"type\":\"Feature\",\"properties\":{\"mag\":6.7,\"place\":\"52km SE of Shizunai, Japan\",\"time\":1452741933640,\"updated\":1459304879040,\"tz\":540,\"url\":\"http://earthquake.usgs.gov/earthquakes/eventpage/us10004ebx\",\"detail\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us10004ebx&format=geojson\",\"felt\":51,\"cdi\":5.8,\"mmi\":6.45,\"alert\":\"green\",\"status\":\"reviewed\",\"tsunami\":1,\"sig\":720,\"net\":\"us\",\"code\":\"10004ebx\",\"ids\":\",us10004ebx,pt16014050,at00o0xauk,gcmt20160114032534,\",\"sources\":\",us,pt,at,gcmt,\",\"types\":\",associate,cap,dyfi,geoserve,impact-link,impact-text,losspager,moment-tensor,nearby-cities,origin,phase-data,shakemap,\",\"nst\":null,\"dmin\":0.281,\"rms\":0.98,\"gap\":22,\"magType\":\"mww\",\"type\":\"earthquake\",\"title\":\"M 6.7 - 52km SE of Shizunai, Japan\"},\"geometry\":{\"type\":\"Point\",\"coordinates\":[142.781,41.9723,46]},\"id\":\"us10004ebx\"},\n" +
"{\"type\":\"Feature\",\"properties\":{\"mag\":6.1,\"place\":\"12km WNW of Charagua, Bolivia\",\"time\":1452741928270,\"updated\":1459304879040,\"tz\":-240,\"url\":\"http://earthquake.usgs.gov/earthquakes/eventpage/us10004ebw\",\"detail\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us10004ebw&format=geojson\",\"felt\":3,\"cdi\":2.2,\"mmi\":2.21,\"alert\":\"green\",\"status\":\"reviewed\",\"tsunami\":0,\"sig\":573,\"net\":\"us\",\"code\":\"10004ebw\",\"ids\":\",us10004ebw,gcmt20160114032528,\",\"sources\":\",us,gcmt,\",\"types\":\",cap,dyfi,geoserve,impact-text,losspager,moment-tensor,nearby-cities,origin,phase-data,shakemap,tectonic-summary,\",\"nst\":null,\"dmin\":5.492,\"rms\":1.04,\"gap\":16,\"magType\":\"mww\",\"type\":\"earthquake\",\"title\":\"M 6.1 - 12km WNW of Charagua, Bolivia\"},\"geometry\":{\"type\":\"Point\",\"coordinates\":[-63.3288,-19.7597,582.56]},\"id\":\"us10004ebw\"},\n" +
"{\"type\":\"Feature\",\"properties\":{\"mag\":6.2,\"place\":\"74km NW of Rumoi, Japan\",\"time\":1452532083920,\"updated\":1459304875040,\"tz\":540,\"url\":\"http://earthquake.usgs.gov/earthquakes/eventpage/us10004djn\",\"detail\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us10004djn&format=geojson\",\"felt\":8,\"cdi\":3.4,\"mmi\":3.74,\"alert\":\"green\",\"status\":\"reviewed\",\"tsunami\":0,\"sig\":594,\"net\":\"us\",\"code\":\"10004djn\",\"ids\":\",us10004djn,gcmt20160111170803,\",\"sources\":\",us,gcmt,\",\"types\":\",cap,dyfi,geoserve,impact-text,losspager,moment-tensor,nearby-cities,origin,phase-data,shakemap,tectonic-summary,\",\"nst\":null,\"dmin\":1.139,\"rms\":0.96,\"gap\":33,\"magType\":\"mww\",\"type\":\"earthquake\",\"title\":\"M 6.2 - 74km NW of Rumoi, Japan\"},\"geometry\":{\"type\":\"Point\",\"coordinates\":[141.0867,44.4761,238.81]},\"id\":\"us10004djn\"},\n" +
"{\"type\":\"Feature\",\"properties\":{\"mag\":6.5,\"place\":\"227km SE of Sarangani, Philippines\",\"time\":1452530285900,\"updated\":1459304874040,\"tz\":480,\"url\":\"http://earthquake.usgs.gov/earthquakes/eventpage/us10004dj5\",\"detail\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us10004dj5&format=geojson\",\"felt\":1,\"cdi\":2.7,\"mmi\":7.5,\"alert\":\"green\",\"status\":\"reviewed\",\"tsunami\":1,\"sig\":650,\"net\":\"us\",\"code\":\"10004dj5\",\"ids\":\",at00o0srjp,pt16011050,us10004dj5,gcmt20160111163807,\",\"sources\":\",at,pt,us,gcmt,\",\"types\":\",cap,dyfi,geoserve,impact-link,impact-text,losspager,moment-tensor,nearby-cities,origin,phase-data,shakemap,tectonic-summary,\",\"nst\":null,\"dmin\":3.144,\"rms\":0.72,\"gap\":22,\"magType\":\"mww\",\"type\":\"earthquake\",\"title\":\"M 6.5 - 227km SE of Sarangani, Philippines\"},\"geometry\":{\"type\":\"Point\",\"coordinates\":[126.8621,3.8965,13]},\"id\":\"us10004dj5\"},\n" +
"{\"type\":\"Feature\",\"properties\":{\"mag\":6,\"place\":\"Pacific-Antarctic Ridge\",\"time\":1451986454620,\"updated\":1459202978040,\"tz\":-540,\"url\":\"http://earthquake.usgs.gov/earthquakes/eventpage/us10004bgk\",\"detail\":\"http://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us10004bgk&format=geojson\",\"felt\":0,\"cdi\":1,\"mmi\":0,\"alert\":\"green\",\"status\":\"reviewed\",\"tsunami\":0,\"sig\":554,\"net\":\"us\",\"code\":\"10004bgk\",\"ids\":\",us10004bgk,gcmt20160105093415,\",\"sources\":\",us,gcmt,\",\"types\":\",cap,dyfi,geoserve,losspager,moment-tensor,nearby-cities,origin,phase-data,shakemap,\",\"nst\":null,\"dmin\":30.75,\"rms\":0.67,\"gap\":71,\"magType\":\"mww\",\"type\":\"earthquake\",\"title\":\"M 6.0 - Pacific-Antarctic Ridge\"},\"geometry\":{\"type\":\"Point\",\"coordinates\":[-136.2603,-54.2906,10]},\"id\":\"us10004bgk\"}],\"bbox\":[-153.4051,-54.2906,10,158.5463,59.6363,582.56]}";
/**
* Create a private constructor because no one should ever create a {@link QueryUtils} object.
* This class is only meant to hold static variables and methods, which can be accessed
* directly from the class name QueryUtils (and an object instance of QueryUtils is not needed).
*/
private QueryUtils() {
}
/**
* Return a list of {@link Earthquake} objects that has been built up from
* parsing a JSON response.
*/
public static ArrayList<Earthquake> extractEarthquakes() {
// Create an empty ArrayList that we can start adding earthquakes to
ArrayList<Earthquake> earthquakes = new ArrayList<>();
// Try to parse the SAMPLE_JSON_RESPONSE. If there's a problem with the way the JSON
// is formatted, a JSONException exception object will be thrown.
// Catch the exception so the app doesn't crash, and print the error message to the logs.
try {
// Parse the response given by the SAMPLE_JSON_RESPONSE string and
// build up a list of Earthquake objects with the corresponding data.
JSONObject BaseJsonResponse = new JSONObject(SAMPLE_JSON_RESPONSE);
// Getting JSON Array Node
JSONArray earthquakeArray = BaseJsonResponse.getJSONArray("Features");
// looping through All Contacts
for (int i = 0; i < earthquakeArray.length(); i++) {
JSONObject currentEarthquake = earthquakeArray.getJSONObject(i);
JSONObject properties= currentEarthquake.getJSONObject("properties");
String magnitude=properties.getString("mag");
String location=properties.getString("place");
String time=properties.getString("time");
Earthquake earthquake= new Earthquake(magnitude,location,time);
earthquakes.add(earthquake);
}
} catch (JSONException e) {
// If an error is thrown when executing any of the above statements in the "try" block,
// catch the exception here, so the app doesn't crash. Print a log message
// with the message from the exception.
Log.e("QueryUtils", "Problem parsing the earthquake JSON results", e);
}
// Return the list of earthquakes
return earthquakes;
}
}
mein Hauptaktivitätscode ist
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ListView;
import java.util.ArrayList;
public class EarthquakeActivity extends AppCompatActivity {
public static final String LOG_TAG = EarthquakeActivity.class.getName();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.earthquake_activity);
// Create a fake list of earthquake locations.
ArrayList<Earthquake> earthquakes = QueryUtils.extractEarthquakes();
// Find a reference to the {@link ListView} in the layout
ListView earthquakeListView = (ListView) findViewById(R.id.list);
// Create an {@link EarthquakeAdapter}, whose data source is a list of
// {@link Earthquake}s. The adapter knows how to create list item views for each item
// in the list.
EarthquakeAdapter quakeAdapter = new EarthquakeAdapter(this,earthquakes);
// Set the adapter on the {@link ListView}
// so the list can be populated in the user interface
earthquakeListView.setAdapter(quakeAdapter);
}
}
Hier ist der Code, der benutzerdefinierten Klasse I gemacht .
public class Earthquake {
//Magnitude of earthquake (e.g. 7.5,5.5,6.4 etc)
private String mMagnitude;
//Place of Earthquake (Kolkata, Delhi etc)
private String mPlace;
// Date Of the occurrence
private String mDate;
/*
* Create a new Earthquake object.
*
* @param vName is the name of the Android version (e.g. Gingerbread)
* @param vNumber is the corresponding Android version number (e.g. 2.3-2.7)
* @param image is drawable reference ID that corresponds to the Android version
* */
public Earthquake(String eMagnitude, String ePlace, String eDate)
{
mMagnitude = eMagnitude;
mPlace = ePlace;
mDate = eDate;
}
/**
* Get value of magnitude
*/
public String getMagnitude() {
return mMagnitude;
}
/**
* Get the place of occurrence
*/
public String getPlace() {
return mPlace;
}
/**
* Get the Date of occurrence
*/
public String getDate() {
return mDate;
}
}
Hier ist der benutzerdefinierte Array-Adapter.
import android.app.Activity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import java.util.ArrayList;
/**
* Created by Atanu on 25-06-2017.
*/
/*
* {@link EarthquakeAdapter} is an {@link ArrayAdapter} that can provide the layout for each list
* based on a data source, which is a list of {@link Earthquake} objects.
* */
public class EarthquakeAdapter extends ArrayAdapter<Earthquake> {
private static final String LOG_TAG = EarthquakeAdapter.class.getSimpleName();
/**
* This is our own custom constructor (it doesn't mirror a superclass constructor).
* The context is used to inflate the layout file, and the list is the data we want
* to populate into the lists.
*
* @param context The current context. Used to inflate the layout file.
* @param earthquakes A List of Earthquake objects to display in a list
*/
public EarthquakeAdapter(Activity context, ArrayList<Earthquake> earthquakes) {
// Here, we initialize the ArrayAdapter's internal storage for the context and the list.
// the second argument is used when the ArrayAdapter is populating a single TextView.
// Because this is a custom adapter for three TextViews , the adapter is not
// going to use this second argument, so it can be any value. Here, we used 0.
super(context, 0, earthquakes);
}
/**
* Provides a view for an AdapterView (ListView, GridView, etc.)
*
* @param position The position in the list of data that should be displayed in the
* list item view.
* @param convertView The recycled view to populate.
* @param parent The parent ViewGroup that is used for inflation.
* @return The View for the position in the AdapterView.
*/
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Check if the existing view is being reused, otherwise inflate the view
View listItemView = convertView;
if(listItemView == null) {
listItemView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
}
// Get the {@link Earthquake} object located at this position in the list
Earthquake currentEarthquake = getItem(position);
// Find the TextView in the list_item.xml layout with the ID mag
TextView magTextView = (TextView) listItemView.findViewById(R.id.mag);
// Get the magnitude from the current Earthquake object and
// set this text on the name TextView
magTextView.setText(currentEarthquake.getMagnitude());
// Find the TextView in the list_item.xml layout with the ID place
TextView placeTextView = (TextView) listItemView.findViewById(R.id.place);
// Get the place of occurrence from the current Earthquake object and
// set this text on the number TextView
placeTextView.setText(currentEarthquake.getPlace());
// Find the Date of occurrence in the list_item.xml layout with the ID date
TextView dateTextView = (TextView) listItemView.findViewById(R.id.date);
// Get the Date of occurrence from the current Earthquake object and
// set the date to TextView
dateTextView.setText(currentEarthquake.getDate());
// Return the whole list item layout (containing 3 TextViews)
// so that it can be shown in the ListView
return listItemView;
}
}
bitte helfen, ich kann nicht voran gehen, ohne dies zu lösen. Vielen Dank im Voraus.
Haben Sie ypu überprüft, ob Ihr getCount nicht 0 zurückgibt? –
irgendein Fehler in logcat? – John