Using sunrise/sunset REST API in Android. How to correctly pass the URL with obtained location coordinates?
Question
I am making an Android application which gets the coordinates of the user's location and then uses those coordinates to talk to a REST API provided by - this website
I am fairly new with JSON parsing and REST API. I have used AsyncTask, Spring and Jackson for it by following this tutorial
My MainActivity.java looks like this -
package com.gamecodeschool.whereintheworld;
import android.content.Context;
import android.location.LocationListener;
import android.location.LocationManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.location.Criteria;
import android.location.Location;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.client.RestTemplate;
import android.os.AsyncTask;
public class MainActivity extends AppCompatActivity implements LocationListener {
private TextView txtLat;
private TextView txtLong;
private TextView txtSource;
private LocationManager locationManager;
private String provider;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
new HttpRequestTask().execute();
setContentView(R.layout.activity_main);
txtLat = (TextView) findViewById(R.id.txtLat);
txtLong = (TextView) findViewById(R.id.txtLong);
txtSource = (TextView) findViewById(R.id.txtSource);
//Initialize locationManager
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
Location location = locationManager.getLastKnownLocation(provider);
//initialize the location
if(location != null){
txtSource.setText("Source = " +provider);
onLocationChanged(location);
}
}
//start updates when app starts/resumes
@Override
protected void onResume() {
super.onResume();
new HttpRequestTask().execute();
locationManager.requestLocationUpdates
(provider, 500, 1, this);
}
@Override
protected void onPause() {
super.onPause();
locationManager.removeUpdates(this);
}
@Override
public void onLocationChanged(Location location) {
double lat = location.getLatitude();
double lng = location.getLongitude();
txtLat.setText(String.valueOf(lat));
txtLong.setText(String.valueOf(lng));
txtSource.setText("Source = " + provider);
}
public String getCoordinates(Location location)
{
double latitude = location.getLatitude();
double longitude = location.getLongitude();
return ("lat="+latitude+"&lng="+longitude);
}
@Override
public void onStatusChanged(String provider,
int status, Bundle extras) {
txtSource.setText("Source = " + provider);
}
@Override
public void onProviderEnabled(String provider) {
txtSource.setText("Source = " + provider);
}
@Override
public void onProviderDisabled(String provider) {
txtSource.setText("Source = " + provider);
}
//USER DEFINED CLASS
private class HttpRequestTask extends AsyncTask<Void, Void, sunrisedata> {
@Override
protected sunrisedata doInBackground(Void... params) {
try {
final String url = "http://api.sunrise-sunset.org/json?";
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
sunrisedata greeting = restTemplate.getForObject(url, sunrisedata.class);
return greeting;
} catch (Exception e) {
Log.e("MainActivity", e.getMessage(), e);
}
return null;
}
@Override
protected void onPostExecute(sunrisedata greeting) {
TextView greetingIdText = (TextView) findViewById(R.id.txtSunrise);
greetingIdText.setText(greeting.getSunrise());
}
}
}
Here in this part of MainActivity.java
final String url = "http://api.sunrise-sunset.org/json?";
I want to pass the coordinates obtained from this part of the code -
public void onLocationChanged(Location location) {
double lat = location.getLatitude();
double lng = location.getLongitude();
txtLat.setText(String.valueOf(lat));
txtLong.setText(String.valueOf(lng));
txtSource.setText("Source = " + provider);
}
Because according to the REST API docs the GET request URL should be in this format -
http://api.sunrise-sunset.org/json?lat=36.7201600&lng=-4.4203400
What is the way in which I can retrieve the latitude and longitude and append it to the URL in the HttpRequestTask class's method -
protected sunrisedata doInBackground(Void... params)
As of now the logcat error looks like this -
04-03 01:56:35.231 13842-1925/com.gamecodeschool.whereintheworld E/MainActivity: Could not read JSON: Unrecognized token 'Array': was expecting ('true', 'false' or 'null')
at [Source: buffer(com.android.okio.GzipSource@1713350c).inputStream(); line: 1, column: 11]; nested exception is com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'Array': was expecting ('true', 'false' or 'null')
at [Source: buffer(com.android.okio.GzipSource@1713350c).inputStream(); line: 1, column: 11]
org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: Unrecognized token 'Array': was expecting ('true', 'false' or 'null')
at [Source: buffer(com.android.okio.GzipSource@1713350c).inputStream(); line: 1, column: 11]; nested exception is com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'Array': was expecting ('true', 'false' or 'null')
at [Source: buffer(com.android.okio.GzipSource@1713350c).inputStream(); line: 1, column: 11]
at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readInternal(MappingJackson2HttpMessageConverter.java:126)
at org.springframework.http.converter.AbstractHttpMessageConverter.read(AbstractHttpMessageConverter.java:147)
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:76)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:484)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:439)
at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:237)
at com.gamecodeschool.whereintheworld.MainActivity$HttpRequestTask.doInBackground(MainActivity.java:111)
at com.gamecodeschool.whereintheworld.MainActivity$HttpRequestTask.doInBackground(MainActivity.java:99)
at android.os.AsyncTask$2.call(AsyncTask.java:292)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
Caused by: com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'Array': was expecting ('true', 'false' or 'null')
at [Source: buffer(com.android.okio.GzipSource@1713350c).inputStream(); line: 1, column: 11]
at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1524)
at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:557)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._reportInvalidToken(UTF8StreamJsonParser.java:3094)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._handleUnexpectedValue(UTF8StreamJsonParser.java:2339)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._nextTokenNotInObject(UTF8StreamJsonParser.java:817)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.nextToken(UTF8StreamJsonParser.java:697)
at com.fasterxml.jackson.databind.ObjectMapper._initForReading(ObjectMapper.java:3031)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2978)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2158)
at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readInternal(MappingJackson2HttpMessageConverter.java:123)
... 13 more
04-03 01:56:35.232 13842-13842/com.gamecodeschool.whereintheworld D/AndroidRuntime: Shutting down VM
04-03 01:56:35.233 13842-13842/com.gamecodeschool.whereintheworld E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.gamecodeschool.whereintheworld, PID: 13842
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.gamecodeschool.whereintheworld.sunrisedata.getSunrise()' on a null object reference
at com.gamecodeschool.whereintheworld.MainActivity$HttpRequestTask.onPostExecute(MainActivity.java:124)
at com.gamecodeschool.whereintheworld.MainActivity$HttpRequestTask.onPostExecute(MainActivity.java:99)
at android.os.AsyncTask.finish(AsyncTask.java:636)
at android.os.AsyncTask.access$500(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:653)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5294)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
04-03 01:56:36.027 13842-2035/com.gamecodeschool.whereintheworld E/MainActivity: Could not read JSON: Unrecognized token 'Array': was expecting ('true', 'false' or 'null')
at [Source: buffer(com.android.okio.GzipSource@3969795b).inputStream(); line: 1, column: 11]; nested exception is com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'Array': was expecting ('true', 'false' or 'null')
at [Source: buffer(com.android.okio.GzipSource@3969795b).inputStream(); line: 1, column: 11]
org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: Unrecognized token 'Array': was expecting ('true', 'false' or 'null')
at [Source: buffer(com.android.okio.GzipSource@3969795b).inputStream(); line: 1, column: 11]; nested exception is com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'Array': was expecting ('true', 'false' or 'null')
at [Source: buffer(com.android.okio.GzipSource@3969795b).inputStream(); line: 1, column: 11]
at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readInternal(MappingJackson2HttpMessageConverter.java:126)
at org.springframework.http.converter.AbstractHttpMessageConverter.read(AbstractHttpMessageConverter.java:147)
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:76)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:484)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:439)
at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:237)
at com.gamecodeschool.whereintheworld.MainActivity$HttpRequestTask.doInBackground(MainActivity.java:111)
at com.gamecodeschool.whereintheworld.MainActivity$HttpRequestTask.doInBackground(MainActivity.java:99)
at android.os.AsyncTask$2.call(AsyncTask.java:292)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
Caused by: com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'Array': was expecting ('true', 'false' or 'null')
at [Source: buffer(com.android.okio.GzipSource@3969795b).inputStream(); line: 1, column: 11]
at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1524)
at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:557)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._reportInvalidToken(UTF8StreamJsonParser.java:3094)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._handleUnexpectedValue(UTF8StreamJsonParser.java:2339)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._nextTokenNotInObject(UTF8StreamJsonParser.java:817)
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.nextToken(UTF8StreamJsonParser.java:697)
at com.fasterxml.jackson.databind.ObjectMapper._initForReading(ObjectMapper.java:3031)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2978)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2158)
at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readInternal(MappingJackson2HttpMessageConverter.java:123)
... 13 more
As far as I figured out this error is coming because the correct URL along with the latitudes and longitudes is not being passed to the website. Obviously the application is also crashing when run on the phone.
Another class which I created by following the tutorial on spring's website is - sunrisedata.java for storing the obtained JSON response looks like this -
package com.gamecodeschool.whereintheworld;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
@JsonIgnoreProperties(ignoreUnknown=true)
public class sunrisedata {
private String results;
public String getSunrise(){
return this.results;
}
}
Please tell me how to correctly pass the lat and long values obtained in MainActivity class to the url in HttpRequestTask class and I just want to retrieve the sunrise data from JSON and ignore all other fields.
1 answers
solution1
0 2017-04-02 22:47:01
Getting the location of a user happens asynchronously which means you will have to wait until the location is returned to you from the LocationManager before you can make the request to get the sunrise/sunset data.
Right now, you are requesting the sunrise/subset data in onResume() which isn't correct. When you do the request here, it is possible that you won't have the location data yet.
It seems like you will want to fetch the sunrise/sunset data in onLocationChanged() . This method will have the location information you need to add to the url.
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