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Ich habe mehr What is a NullPointerException, and how do I fix it? Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference und ein paar lesen, aber ich habe kein Glück hatte es zu reparieren.com.android.volley.VolleyError: java.lang.NullPointerException
Dies ist der Fehler, die ich von Volley Fehler Hörer bekommen -
com.android.volley.VolleyError: java.lang.NullPointerException: Der Versuch, virtuelle Methode ‚int java.lang.String.length aufzurufen () 'auf einem Nullobjekt Referenz
Ich bin relativ neu zu Android, könnte mir bitte jemand erklären, was die Ursache für mein Problem und mir helfen, es zu beheben?
Unten ist der Code für die Aktivität, die die Volley Anfrage macht -
public class CircleActivity extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener {
private Toolbar toolbar;
private FloatingActionButton fab;
private ArrayList<Users> listUsers = new ArrayList<>();
SessionManager sessionManager;
BroadcastReceiver broadcastReceiver;
private RecyclerView listUsersCircle;
//swipe
private SwipeRefreshLayout swipeRefreshLayout;
//volley login
//mobile hotspot
//public static final String REGISTER_URL = "http://192.168.43.181/save/user/getPeopleList";
//ghar
public final String REGISTER_URL = "http://192.168.0.10/save/user/getPeopleList";
private CircleListAdapter circleListAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
sessionManager = new SessionManager(getApplicationContext());
if (sessionManager.isLoggedIn()) {
setContentView(R.layout.activity_circle);
toolbar = (Toolbar) findViewById(R.id.app_bar);
//tell android to use my toolbar
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
NavigationDrawerFragment drawerFragment = (NavigationDrawerFragment)
getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), toolbar);
listUsersCircle = (RecyclerView) findViewById(R.id.circle);
listUsersCircle.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
circleListAdapter = new CircleListAdapter(getApplicationContext());
listUsersCircle.setAdapter(circleListAdapter);
swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipe_refresh_circle);
swipeRefreshLayout.setOnRefreshListener(this);
sendJsonRequest();
//get user_id from session
String user_id = sessionManager.getUserDetails().get("user_id");
//adding data to the intent
Intent intent = new Intent(getBaseContext), LocationService.class);
intent.putExtra("user_id", user_id);
startService(intent);
fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String phoneNumber="123123123412";
String message ="Hello sms";
sendSMS(phoneNumber,message);
}
});
//location service
// startService(new Intent(getBaseContext(), LocationService.class));
//swipe to refresh
/* JSONObject obj = new JSONObject();
try {
obj.put("txtCircleId", "acca16d632");
} catch (JSONException e) {
e.printStackTrace();
}
Log.d("Nishon",obj.toString());
RequestQueue requestQueue = VolleySingleton.getsInstance().getRequestQueue();
JsonObjectRequest request = new JsonObjectRequest(Request.Method.POST,
URL_GET_CIRCLE_USERS,
obj,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
Toast.makeText(getApplicationContext(), response.toString(), Toast.LENGTH_LONG).show();
Log.d("Nishon",response.toString());
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.d("Nishon", error.toString());
}
});
requestQueue.add(request);*/
} else {
Intent intent = new Intent(this, LoginActivity.class);
startActivity(intent);
finish();
}
}
private void sendSMS(String phoneNumber, String message)
{
PendingIntent pi = PendingIntent.getActivity(this, 0,
new Intent(this, SMS.class), 0);
SmsManager sms = SmsManager.getDefault();
sms.sendTextMessage(phoneNumber, null, message, pi, null);
}
public void sendJsonRequest() {
RequestQueue requestQueue = VolleySingleton.getsInstance().getRequestQueue();
StringRequest request = new StringRequest(Request.Method.POST, REGISTER_URL,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
listUsers = parseJsonResponse(response);
circleListAdapter.setCircleList(listUsers);
Log.d("d",response);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getApplicationContext(), error.toString(), Toast.LENGTH_LONG).show();
Log.d("d", error.toString());
}
}) {
@Override
protected Map<String, String> getParams() {
Map<String, String> params = new HashMap<String, String>();
String group_key= sessionManager.getUserDetails().get("group_key");
params.put("group_key", group_key);
return params;
}
};
requestQueue.add(request);
}
public ArrayList<Users> parseJsonResponse(String response) {
ArrayList<Users> listUsers = new ArrayList<>();
if (response != null || response.length() > 0) {
Toast.makeText(getApplicationContext(), response.toString(), Toast.LENGTH_LONG).show();
JSONObject jsonObject = null;
try {
jsonObject = new JSONObject(response.toString());
} catch (JSONException e) {
e.printStackTrace();
}
//extracting json array from response string
JSONArray jsonArray = null;
try {
if (jsonObject.has("users")) {
jsonArray = jsonObject.getJSONArray("users");
for (int z = 0; z < jsonArray.length(); z++) {
JSONObject currentUser = jsonArray.getJSONObject(z);
//String email = currentUser.getString("email");
String fname = currentUser.getString("first_name");
String lname = currentUser.getString("last_name");
Users user = new Users();
user.setFname(fname);
user.setLname(lname);
listUsers.add(user);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
/* JSONObject jsonRow = null;
try {
jsonRow = jsonArray.getJSONObject(1);
} catch (JSONException e) {
e.printStackTrace();
}
//get value from jsonRow
try {
String resultStr = jsonRow.getString("email");
Log.d("Nishon", resultStr);
} catch (JSONException e) {
e.printStackTrace();
}*/
}
return listUsers;
}
@Override
protected void onPause() {
super.onPause();
finish();
}
public void showNotification(View view) {
}
@Override
public void onRefresh() {
swipeRefreshLayout.setRefreshing(true);
sendJsonRequest();
swipeRefreshLayout.setRefreshing(false);
}
/*@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_POWER) {
// Do something here...
event.startTracking(); // Needed to track long presses
return true;
}
return super.onKeyDown(keyCode, event);
}
*/
}
Der Webservice arbeitet.