Ниже приведена программа Mainactivity, всякий раз, когда я пытаюсь запустить ее, получаю ошибку, например
в com.example.soonami.MainActivity $ TsunamiAsyncTask.makeHttpRequest (MainActivity. java: 170) в com.example.soonami .MainActivity $ TsunamiAsyncTask.doInBackground (MainActivity. java: 114) в com.example.soonami.MainActivity $ TsunamiAsyncTask.doInBackground (MainActivity. java: 103)
package com.example.soonami;
import android.os.AsyncTask;
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import android.util.Log;
import android.widget.TextView;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.charset.Charset;
import java.text.SimpleDateFormat;
/**
* Displays information about a single earthquake.
*/
public class MainActivity extends AppCompatActivity {
/** Tag for the log messages */
public static final String LOG_TAG = MainActivity.class.getSimpleName();
/** URL to query the USGS dataset for earthquake information */
private static final String USGS_REQUEST_URL =
"https://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&starttime=2012-01-01&endtime=2012-12-01&minmagnitude=6";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Kick off an {@link AsyncTask} to perform the network request
TsunamiAsyncTask task = new TsunamiAsyncTask();
task.execute();
}
/**
* Update the screen to display information from the given {@link Event}.
*/
private void updateUi(Event earthquake) {
// Display the earthquake title in the UI
TextView titleTextView = (TextView) findViewById(R.id.title);
titleTextView.setText(earthquake.title);
// Display the earthquake date in the UI
TextView dateTextView = (TextView) findViewById(R.id.date);
dateTextView.setText(getDateString(earthquake.time));
// Display whether or not there was a tsunami alert in the UI
TextView tsunamiTextView = (TextView) findViewById(R.id.tsunami_alert);
tsunamiTextView.setText(getTsunamiAlertString(earthquake.tsunamiAlert));
}
/**
* Returns a formatted date and time string for when the earthquake happened.
*/
private String getDateString(long timeInMilliseconds) {
SimpleDateFormat formatter = new SimpleDateFormat("EEE, d MMM yyyy 'at' HH:mm:ss z");
return formatter.format(timeInMilliseconds);
}
/**
* Return the display string for whether or not there was a tsunami alert for an earthquake.
*/
private String getTsunamiAlertString(int tsunamiAlert) {
switch (tsunamiAlert) {
case 0:
return getString(R.string.alert_no);
case 1:
return getString(R.string.alert_yes);
default:
return getString(R.string.alert_not_available);
}
}
/**
* {@link AsyncTask} to perform the network request on a background thread, and then
* update the UI with the first earthquake in the response.
*/
private class TsunamiAsyncTask extends AsyncTask<URL, Void, Event> {
@Override
protected Event doInBackground(URL... urls) {
// Create URL object
URL url = createUrl(USGS_REQUEST_URL);
// Perform HTTP request to the URL and receive a JSON response back
String jsonResponse = "";
try {
jsonResponse = makeHttpRequest(url);
} catch (IOException e) {
// TODO Handle the IOException
}
// Extract relevant fields from the JSON response and create an {@link Event} object
Event earthquake = extractFeatureFromJson(jsonResponse);
// Return the {@link Event} object as the result fo the {@link TsunamiAsyncTask}
return earthquake;
}
/**
* Update the screen with the given earthquake (which was the result of the
* {@link TsunamiAsyncTask}).
*/
@Override
protected void onPostExecute(Event earthquake) {
if (earthquake == null) {
return;
}
updateUi(earthquake);
}
/**
* Returns new URL object from the given string URL.
*/
private URL createUrl(String stringUrl) {
URL url = null;
try {
url = new URL(stringUrl);
} catch (MalformedURLException exception) {
Log.e(LOG_TAG, "Error with creating URL", exception);
return null;
}
return url;
}
/**
* Make an HTTP request to the given URL and return a String as the response.
*/
private String makeHttpRequest(URL url) throws IOException {
String jsonResponse = "";
if (url == null) {
return jsonResponse;
}
HttpURLConnection urlConnection = null;
InputStream inputStream = null;
try {
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setReadTimeout(10000 /* milliseconds */);
urlConnection.setConnectTimeout(15000 /* milliseconds */);
urlConnection.connect();
if (urlConnection.getResponseCode() == 200) {
inputStream = urlConnection.getInputStream();
jsonResponse = readFromStream(inputStream);
} else {
Log.e(LOG_TAG, "Invalid response code " + urlConnection.getResponseCode());
}
} catch (IOException e) {
// TODO: Handle the exception
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (inputStream != null) {
// function must handle java.io.IOException here
inputStream.close();
}
}
return jsonResponse;
}
/**
* Convert the {@link InputStream} into a String which contains the
* whole JSON response from the server.
*/
private String readFromStream(InputStream inputStream) throws IOException {
StringBuilder output = new StringBuilder();
if (inputStream != null) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(inputStreamReader);
String line = reader.readLine();
while (line != null) {
output.append(line);
line = reader.readLine();
}
}
return output.toString();
}
/**
* Return an {@link Event} object by parsing out information
* about the first earthquake from the input earthquakeJSON string.
*/
private Event extractFeatureFromJson(String earthquakeJSON) {
try {
JSONObject baseJsonResponse = new JSONObject(earthquakeJSON);
JSONArray featureArray = baseJsonResponse.getJSONArray("features");
// If there are results in the features array
if (featureArray.length() > 0) {
// Extract out the first feature (which is an earthquake)
JSONObject firstFeature = featureArray.getJSONObject(0);
JSONObject properties = firstFeature.getJSONObject("properties");
// Extract out the title, time, and tsunami values
String title = properties.getString("title");
long time = properties.getLong("time");
int tsunamiAlert = properties.getInt("tsunami");
// Create a new {@link Event} object
return new Event(title, time, tsunamiAlert);
}
} catch (JSONException e) {
Log.e(LOG_TAG, "Problem parsing the earthquake JSON results", e);
}
return null;
}
}
}