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POGetting JSON in Android App
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copied!<p>I am trying to parse some JSON in my app. I have an activity that the user types in their location and presses a button which opens another activity. The problem is that the app crashes when opening the second activity. I used a tutorial to figure out how to get the JSON data but can't figure out what I'm doing wrong. I'm pretty new to Android development so any ideas or help are greatly appreciated.</p> <p>Here is my code:</p> <pre><code>import android.app.Activity; import android.content.Context; import android.content.Intent; import android.os.Bundle; import android.view.KeyEvent; import android.view.View; import android.view.inputmethod.EditorInfo; import android.view.inputmethod.InputMethodManager; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; import android.widget.TextView.OnEditorActionListener; public class WeatherLocation extends Activity { EditText locationText; TextView label; Button getWeather; String enteredText; String url = "http://api.worldweatheronline.com/free/v1/weather.ashx?q=%s&format=json&num_of_days=5&key=37a5fj42xpyptvjgkhrx5rwu"; String newURL; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.weatherlocation); locationText = (EditText) findViewById(R.id.locationText); label = (TextView) findViewById(R.id.label); getWeather = (Button) findViewById(R.id.showWeather); locationText.setText("Current Location"); locationText.setOnEditorActionListener(new OnEditorActionListener() { @Override public boolean onEditorAction(TextView v, int actionId, KeyEvent event) { boolean handled = false; if (actionId == EditorInfo.IME_ACTION_DONE) { enteredText = locationText.getText().toString(); System.out.println(enteredText); // hide the virtual keyboard InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE); imm.hideSoftInputFromWindow(getCurrentFocus().getWindowToken(), InputMethodManager.RESULT_UNCHANGED_SHOWN); newURL = String.format(url, enteredText); System.out.println("Formatted URL: " + newURL); handled = true; } return handled; } }); getWeather.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { Intent weather = new Intent(WeatherLocation.this, Weather.class); startActivity(weather); } }); } } </code></pre> <p>Weather info class:</p> <pre><code>import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.UnsupportedEncodingException; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import android.os.Bundle; import android.util.Log; import android.widget.TextView; public class Weather extends WeatherLocation { TextView currentTemp; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.weather); currentTemp = (TextView) findViewById(R.id.currentTemp); // Create instance of JSONParser JSONParser jParser = new JSONParser(); // getting JSON string from URL System.out.println(newURL); JSONObject json = jParser.getJSONFromUrl(newURL); try { JSONObject data = new JSONObject(json.getString("data")); JSONArray currentConditions = data.getJSONArray("current_condition"); JSONArray weather = data.getJSONArray("weather"); JSONObject temp = currentConditions.getJSONObject(0); String fahr = temp.getString("temp_F"); currentTemp.setText(fahr); } catch(Exception e) { e.getMessage().toString(); } } public static class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } public JSONObject getJSONFromUrl(String url) { // Making HTTP request try { // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try to parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; } } } </code></pre> <p>Errors:</p> <pre><code>10-14 13:11:28.523: E/AndroidRuntime(6583): FATAL EXCEPTION: main 10-14 13:11:28.523: E/AndroidRuntime(6583): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kentuckyfarmbureau.kyfb/com.kentuckyfarmbureau.kyfb.Weather}: java.lang.NullPointerException 10-14 13:11:28.523: E/AndroidRuntime(6583): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211) 10-14 13:11:28.523: E/AndroidRuntime(6583): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261) 10-14 13:11:28.523: E/AndroidRuntime(6583): at android.app.ActivityThread.access$600(ActivityThread.java:141) 10-14 13:11:28.523: E/AndroidRuntime(6583): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256) 10-14 13:11:28.523: E/AndroidRuntime(6583): at android.os.Handler.dispatchMessage(Handler.java:99) 10-14 13:11:28.523: E/AndroidRuntime(6583): at android.os.Looper.loop(Looper.java:137) 10-14 13:11:28.523: E/AndroidRuntime(6583): at android.app.ActivityThread.main(ActivityThread.java:5103) 10-14 13:11:28.523: E/AndroidRuntime(6583): at java.lang.reflect.Method.invokeNative(Native Method) 10-14 13:11:28.523: E/AndroidRuntime(6583): at java.lang.reflect.Method.invoke(Method.java:525) 10-14 13:11:28.523: E/AndroidRuntime(6583): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 10-14 13:11:28.523: E/AndroidRuntime(6583): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 10-14 13:11:28.523: E/AndroidRuntime(6583): at dalvik.system.NativeStart.main(Native Method) 10-14 13:11:28.523: E/AndroidRuntime(6583): Caused by: java.lang.NullPointerException 10-14 13:11:28.523: E/AndroidRuntime(6583): at com.android.internal.os.LoggingPrintStream.println(LoggingPrintStream.java:298) 10-14 13:11:28.523: E/AndroidRuntime(6583): at com.kentuckyfarmbureau.kyfb.Weather.onCreate(Weather.java:42) 10-14 13:11:28.523: E/AndroidRuntime(6583): at android.app.Activity.performCreate(Activity.java:5133) 10-14 13:11:28.523: E/AndroidRuntime(6583): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 10-14 13:11:28.523: E/AndroidRuntime(6583): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175) 10-14 13:11:28.523: E/AndroidRuntime(6583): ... 11 more </code></pre> <p>EDIT: I have edited the code in Weather.java (the second activity) to include this:</p> <pre><code>Intent intent = getIntent(); String url = intent.getStringExtra("INTENT_KEY_URL"); System.out.println(url); JSONObject json = jParser.getJSONFromUrl(url); </code></pre>

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