im trying to make an app where users can log in and save their userdata to an mysql-db. Im using PreferenceActivity and PreferenceFragment to handle this. Usually this works fine until i change the users...
Now the error occurs when User A logs out and User B logs in. (shared prefs are cleared with the clear(). and commit() when logging out..)
Application stops with
java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.File android.content.Context.getCacheDir()'
on a null object reference
at com.android.volley.toolbox.Volley.newRequestQueue(Volley.java: 43)
at com.android.volley.toolbox.Volley.newRequestQueue(Volley.java: 78)
at com.jamp.jamp.UserProfileSettingsFragment.onSharedPreferenceChanged(UserProfileSettingsFragment.java: 171)
at android.app.SharedPreferencesImpl$EditorImpl.notifyListeners(SharedPreferencesImpl.java: 479)
at android.app.SharedPreferencesImpl$EditorImpl.apply(SharedPreferencesImpl.java: 387)
at android.preference.Preference.tryCommit(Preference.java: 1415)
at android.preference.Preference.persistString(Preference.java: 1448)
at android.preference.EditTextPreference.setText(EditTextPreference.java: 94)
at android.preference.EditTextPreference.onDialogClosed(EditTextPreference.java: 148)
at android.preference.DialogPreference.onDismiss(DialogPreference.java: 395)
at android.app.Dialog$ListenersHandler.handleMessage(Dialog.java: 1337)
at android.os.Handler.dispatchMessage(Handler.java: 102)
at android.os.Looper.loop(Looper.java: 154)
at android.app.ActivityThread.main(ActivityThread.java: 6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java: 866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 756)Now this is the code of the fragment
package com.jamp.jamp;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.Preference;
import android.preference.PreferenceFragment;
import android.preference.PreferenceManager;
import android.support.v7.app.AlertDialog;
import android.widget.Toast;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.toolbox.Volley;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.util.HashMap;
/**
* Created by Erikken on 05.09.2017.
*/
public class UserProfileSettingsFragment extends PreferenceFragment implements SharedPreferences.OnSharedPreferenceChangeListener {
SessionManager session;
SharedPreferences prefs;
String prefs_realname;
String prefs_email;
String prefs_streetname;
String prefs_postcode;
String prefs_city;
String prefs_state;
@Override
public void onCreate(final Bundle savedInstanceState) {
prefs = this.getActivity().getSharedPreferences("JampSharedPrefs", Context.MODE_PRIVATE);
final SharedPreferences.Editor editor = prefs.edit();
PreferenceManager.getDefaultSharedPreferences(getActivity()).registerOnSharedPreferenceChangeListener(this);
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.usersettings);
session = new SessionManager(this.getActivity().getApplicationContext());
HashMap < String, String > user = session.getUserDetails();
final String sessionUsername = user.get(SessionManager.KEY_USERNAME);
// ResponseListener um Request Nutzerdaten auszulesen.
Response.Listener < String > UserDataResponseListener = new Response.Listener < String > () {
@Override
public void onResponse(String response) {
try {
JSONObject jsonResponse = new JSONObject(response);
boolean success = jsonResponse.getBoolean("success");
// Wenn Datenabfrage erfolgreich, JSONResponse auswerten. // If successful, import data from mysql database
if (success) {
String responseRealName = jsonResponse.getString("realname");
if (responseRealName.equals("")) {
responseRealName = getResources().getString(R.string.MissingRealName);
}
String responseEmail = jsonResponse.getString("email");
if (responseEmail.equals("")) {
responseEmail = getResources().getString(R.string.MissingEmail);
}
String responseStreetName = jsonResponse.getString("streetname");
if (responseStreetName.equals("")) {
responseStreetName = getResources().getString(R.string.MissingStreetName);
}
String responsePostcode = jsonResponse.getString("postcode");
if (responsePostcode.equals("")) {
responsePostcode = getResources().getString(R.string.MissingPostcode);
}
String responseCity = jsonResponse.getString("city");
if (responseCity.equals("")) {
responseCity = getResources().getString(R.string.MissingCity);
}
String responseState = jsonResponse.getString("state");
if (responseState.equals("")) {
responseState = getResources().getString(R.string.MissingState);
}
int responseAge = jsonResponse.getInt("age");
int responseIsPremium = jsonResponse.getInt("isPremium"); // BOOLEAN
// Add data to shared prefs
editor.putString("realname", responseRealName);
editor.putString("email", responseEmail);
editor.putString("streetname", responseStreetName);
editor.putString("postcode", responsePostcode);
editor.putString("city", responseCity);
editor.putString("state", responseState);
editor.commit();
prefs_realname = prefs.getString("realname", "");
prefs_email = prefs.getString("email", "");
prefs_streetname = prefs.getString("streetname", "");
prefs_postcode = prefs.getString("postcode", "");
prefs_city = prefs.getString("city", "");
prefs_state = prefs.getString("state", "");
Preference prefUserData = (Preference) findPreference("preferencescreen_userdata");
prefUserData.setTitle(sessionUsername);
prefUserData.setSummary(prefs_realname + "\n" +
prefs_email + "\n" +
prefs_streetname + "\n" +
prefs_postcode + " " + prefs_city + "\n" +
prefs_state);
findPreference("settings_username").setTitle(sessionUsername);
findPreference("settings_realname").setSummary(prefs_realname);
findPreference("settings_email").setSummary(prefs_email);
findPreference("settings_streetname").setSummary(prefs_streetname);
findPreference("settings_postcode").setSummary(prefs_postcode);
findPreference("settings_city").setSummary(prefs_city);
findPreference("settings_state").setSummary(prefs_state);
} else {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setMessage("Konnte Nutzerdaten nicht abrufen.")
.setNegativeButton("Nochmal", null)
.create()
.show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
};
// Request an userdatarequest.php senden / Send request to userdatarequest.php
UserDataRequest userDataRequest = new UserDataRequest(sessionUsername, UserDataResponseListener);
RequestQueue queue = Volley.newRequestQueue(this.getActivity());
queue.add(userDataRequest);
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
HashMap < String, String > user = session.getUserDetails();
final String sessionUsername = user.get(SessionManager.KEY_USERNAME);
final String sessionPassword = user.get(SessionManager.KEY_PASSWORD);
Context mContext = getActivity().getApplicationContext();
Response.Listener < String > UpdateUserDataResponseListener = new Response.Listener < String > () {
@Override
public void onResponse(String response) {
try {
JSONObject jsonResponse = new JSONObject(response);
boolean success = jsonResponse.getBoolean("success");
if (success) {
Toast.makeText(getActivity().getApplicationContext(), "Change Successful", Toast.LENGTH_LONG).show();
} else {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setMessage("Konnte Nutzerdaten nicht abrufen.")
.setNegativeButton("Nochmal", null)
.create()
.show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
};
if (key.equals("settings_email")) {
// An mySQLDB senden
UpdateUserDataRequest updateUserDataRequest = new UpdateUserDataRequest(sessionUsername, sessionPassword, "email", sharedPreferences.getString(key, ""), UpdateUserDataResponseListener);
RequestQueue queue = Volley.newRequestQueue(mContext);
queue.add(updateUserDataRequest);
// Summary sofort erneuern. // Refresh Summaries
prefs_email = sharedPreferences.getString(key, "");
findPreference(key).setSummary(prefs_email);
findPreference("preferencescreen_userdata").setSummary(prefs_realname + "\n" +
prefs_email + "\n" +
prefs_streetname + "\n" +
prefs_postcode + " " + prefs_city + "\n" +
prefs_state);
}
// LOTS OF SIMILAR BUTTONS FOLLOWING HERE...
}
}So the error uccurs only one time after relogging the user. When it crashed once everythin seems reset, the app restarts and he can change any of his data as often as he wants.
am i using the mContext variable wrong? are there some ramaining values i didnt clear that can lead to a crash?
any tips? =/
Okay, i got it. Found some other threads with a similar problem.
my Context mContext = getActivity().getApplicationContext(); is called in the OnPreferenceChange method. But this seems to early because the onCreate Method in the Fragment has not been called yet and there is just no activity where my context should point, so this returns null. I moved the mContext variable to the onCreate method, deleted it from onPreferenceChange (made some other adjustments aswell..) and now onPreferenceChange seems to wait for the onCreate method and it works perfectly.
package com.jamp.jamp;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.Preference;
import android.preference.PreferenceFragment;
import android.preference.PreferenceManager;
import android.support.v7.app.AlertDialog;
import android.widget.Toast;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.toolbox.Volley;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.util.HashMap;
/**
* Created by Erikken on 05.09.2017.
*/
public class UserProfileSettingsFragment extends PreferenceFragment implements SharedPreferences.OnSharedPreferenceChangeListener
{
SessionManager session;
Context mContext;
String prefs_realname;
String prefs_email;
String prefs_streetname;
String prefs_postcode;
String prefs_city;
String prefs_state;
@Override
public void onCreate(final Bundle savedInstanceState)
{
final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity().getApplicationContext());
final SharedPreferences.Editor editor = prefs.edit();
prefs.registerOnSharedPreferenceChangeListener(this);
mContext = getActivity().getApplicationContext();
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.usersettings);
session = new SessionManager(getActivity().getApplicationContext());
session.CheckLogin();
HashMap<String,String> user = session.getUserDetails();
final String sessionUsername = user.get(SessionManager.KEY_USERNAME);
final String sessionPassword = user.get(SessionManager.KEY_PASSWORD);
// ResponseListener um Request Nutzerdaten auszulesen.
Response.Listener<String> UserDataResponseListener = new Response.Listener<String>(){
@Override
public void onResponse(String response) {
try {
JSONObject jsonResponse = new JSONObject(response);
boolean success = jsonResponse.getBoolean("success");
// Wenn Datenabfrage erfolgreich, JSONResponse auswerten. // If successful, import data from mysql database
if (success) {
String responseRealName = jsonResponse.getString("realname"); if (responseRealName.equals("")) {responseRealName = getResources().getString(R.string.MissingRealName);}
String responseEmail = jsonResponse.getString("email"); if (responseEmail.equals("")) {responseEmail= getResources().getString(R.string.MissingEmail);}
String responseStreetName = jsonResponse.getString("streetname"); if (responseStreetName.equals("")) {responseStreetName = getResources().getString(R.string.MissingStreetName);}
String responsePostcode = jsonResponse.getString("postcode"); if (responsePostcode.equals("")) {responsePostcode = getResources().getString(R.string.MissingPostcode);}
String responseCity = jsonResponse.getString("city"); if (responseCity.equals("")) {responseCity = getResources().getString(R.string.MissingCity);}
String responseState = jsonResponse.getString("state"); if (responseState.equals("")) {responseState = getResources().getString(R.string.MissingState);}
int responseAge = jsonResponse.getInt ("age");
int responseIsPremium = jsonResponse.getInt ("isPremium"); // BOOLEAN
// Add data to shared prefs
editor.putString("realname",responseRealName);
editor.putString("email",responseEmail);
editor.putString("streetname",responseStreetName);
editor.putString("postcode",responsePostcode);
editor.putString("city",responseCity);
editor.putString("state",responseState);
editor.commit();
prefs_realname = prefs.getString("realname","0");
prefs_email = prefs.getString("email","0");
prefs_streetname = prefs.getString("streetname","0");
prefs_postcode = prefs.getString("postcode","0");
prefs_city = prefs.getString("city","0");
prefs_state = prefs.getString("state","0");
Preference prefUserData = (Preference) findPreference("preferencescreen_userdata");
prefUserData.setTitle(sessionUsername);
prefUserData.setSummary(prefs_realname+"\n"
+prefs_email+"\n"
+prefs_streetname+"\n"
+prefs_postcode + " " + prefs_city +"\n"
+prefs_state);
findPreference("settings_username").setTitle(sessionUsername);
findPreference("settings_realname").setSummary(prefs_realname);
findPreference("settings_email").setSummary(prefs_email);
findPreference("settings_streetname").setSummary(prefs_streetname);
findPreference("settings_postcode").setSummary(prefs_postcode);
findPreference("settings_city").setSummary(prefs_city);
findPreference("settings_state").setSummary(prefs_state);
}else{
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setMessage("Konnte Nutzerdaten nicht abrufen.")
.setNegativeButton("Nochmal",null)
.create()
.show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
};
// Request an userdatarequest.php senden / Send request to userdatarequest.php
UserDataRequest userDataRequest = new UserDataRequest(sessionUsername, UserDataResponseListener);
RequestQueue queue = Volley.newRequestQueue(getActivity());
queue.add(userDataRequest);
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
session = new SessionManager(mContext);
HashMap<String,String> user = session.getUserDetails();
final String sessionUsername = user.get(SessionManager.KEY_USERNAME);
final String sessionPassword = user.get(SessionManager.KEY_PASSWORD);
Response.Listener<String> UpdateUserDataResponseListener = new Response.Listener<String>(){
@Override
public void onResponse(String response) {
try {
JSONObject jsonResponse = new JSONObject(response);
boolean success = jsonResponse.getBoolean("success");
if (success){
Toast.makeText(mContext,"Change Successful",Toast.LENGTH_LONG).show();
}else{
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setMessage("Konnte Nutzerdaten nicht abrufen.")
.setNegativeButton("Nochmal",null)
.create()
.show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
};
if (key.equals("settings_email")){ // Adressenprüfung mussnoch implementiert werden.
// An mySQLDB senden
//CELLNAME // CELLVALUE
UpdateUserDataRequest updateUserDataRequest = new UpdateUserDataRequest(sessionUsername, sessionPassword, "email", sharedPreferences.getString(key, ""), UpdateUserDataResponseListener);
RequestQueue queue = Volley.newRequestQueue(mContext);
queue.add(updateUserDataRequest);
// Summary sofort erneuern. // Refresh Summaries instantly
prefs_email = sharedPreferences.getString(key, "");
findPreference(key).setSummary(prefs_email);
findPreference("preferencescreen_userdata").setSummary(prefs_realname + "\n"
+ prefs_email + "\n"
+ prefs_streetname + "\n"
+ prefs_postcode + " " + prefs_city + "\n"
+ prefs_state);
}
if (key.equals("settings_streetname")){
UpdateUserDataRequest updateUserDataRequest = new UpdateUserDataRequest(sessionUsername,sessionPassword,"streetname",sharedPreferences.getString(key,""), UpdateUserDataResponseListener);
RequestQueue queue = Volley.newRequestQueue(mContext);
queue.add(updateUserDataRequest);
// Summary sofort erneuern. // Refresh Summaries instantly
prefs_streetname = sharedPreferences.getString(key,"");
findPreference(key).setSummary(prefs_streetname);
findPreference("preferencescreen_userdata").setSummary(prefs_realname+"\n"
+prefs_email+"\n"
+prefs_streetname+"\n"
+prefs_postcode + " " + prefs_city +"\n"
+prefs_state);
}
if (key.equals("settings_realname")){
UpdateUserDataRequest updateUserDataRequest = new UpdateUserDataRequest(sessionUsername,sessionPassword,"realname",sharedPreferences.getString(key,""), UpdateUserDataResponseListener);
RequestQueue queue = Volley.newRequestQueue(mContext);
queue.add(updateUserDataRequest);
// Summary sofort erneuern. // Refresh Summaries instantly
prefs_realname = sharedPreferences.getString(key,"");
findPreference(key).setSummary(prefs_realname);
findPreference("preferencescreen_userdata").setSummary(prefs_realname+"\n"
+prefs_email+"\n"
+prefs_streetname+"\n"
+prefs_postcode + " " + prefs_city +"\n"
+prefs_state);
}
if (key.equals("settings_postcode")){
UpdateUserDataRequest updateUserDataRequest = new UpdateUserDataRequest(sessionUsername,sessionPassword,"postcode",sharedPreferences.getString(key,""), UpdateUserDataResponseListener);
RequestQueue queue = Volley.newRequestQueue(mContext);
queue.add(updateUserDataRequest);
// Summary sofort erneuern. // Refresh Summaries instantly
prefs_postcode = sharedPreferences.getString(key,"");
findPreference(key).setSummary(prefs_postcode);
findPreference("preferencescreen_userdata").setSummary(prefs_realname+"\n"
+prefs_email+"\n"
+prefs_streetname+"\n"
+prefs_postcode + " " + prefs_city +"\n"
+prefs_state);
}
if (key.equals("settings_city")) {
UpdateUserDataRequest updateUserDataRequest = new UpdateUserDataRequest(sessionUsername,sessionPassword,"city",sharedPreferences.getString(key,""), UpdateUserDataResponseListener);
RequestQueue queue = Volley.newRequestQueue(mContext);
queue.add(updateUserDataRequest);
// Summary sofort erneuern. // Refresh Summaries instantly
prefs_city = sharedPreferences.getString(key,"");
findPreference(key).setSummary(prefs_city);
findPreference("preferencescreen_userdata").setSummary(prefs_realname+"\n"
+prefs_email+"\n"
+prefs_streetname+"\n"
+prefs_postcode + " " + prefs_city +"\n"
+prefs_state);
}
if (key.equals("settings_state")) {
UpdateUserDataRequest updateUserDataRequest = new UpdateUserDataRequest(sessionUsername,sessionPassword,"state",sharedPreferences.getString(key,""), UpdateUserDataResponseListener);
RequestQueue queue = Volley.newRequestQueue(mContext);
queue.add(updateUserDataRequest);
// Summary sofort erneuern. // Refresh Summaries instantly
prefs_state = sharedPreferences.getString(key,"");
findPreference(key).setSummary(prefs_state);
findPreference("preferencescreen_userdata").setSummary(prefs_realname+"\n"
+prefs_email+"\n"
+prefs_streetname+"\n"
+prefs_postcode + " " + prefs_city +"\n"
+prefs_state);
}
}
}