Develop Reference

This code doesn't get any error in android Emulator but in Real device error appear, It's about network change listner

This the code :
package app.nepaliapp.bscfree.Utility;
import android.app.AlertDialog;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import androidx.appcompat.widget.AppCompatButton;
import app.nepaliapp.bscfree.R;
public class NetworkChangeListener extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
if (!Common.isConnectedToInternet(context)) {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
View layout_dialog = LayoutInflater.from(context).inflate(R.layout.check_internet_dialog, null);
builder.setView(layout_dialog);
AppCompatButton btnRetry = layout_dialog.findViewById(R.id.btnRetry);
//show dialog
AlertDialog dialog = builder.create();
dialog.show();
dialog.setCancelable(false);
dialog.getWindow().setGravity(Gravity.CENTER);
btnRetry.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
dialog.dismiss();
onReceive(context, intent);
}
});
}
}
}
This code work good at emulator and Fuction as expected but when published run in other device like android it doesn't works.
The error seen in my console panel is this:
Caused by android.view.WindowManager$BadTokenException
Unable to add window -- token android.os.BinderProxy#21ba88d is not valid; is your activity running?
android.view.ViewRootImpl.setView (ViewRootImpl.java:1068)
android.app.Dialog.show (Dialog.java:340)
app.nepaliapp.bscfree.Utility.NetworkChangeListener.onReceive (NetworkChangeListener.java:32)
android.app.LoadedApk$ReceiverDispatcher$Args.lambda$getRunnable$0$LoadedApk$ReceiverDispatcher$Args (LoadedApk.java:1556)
com.android.internal.os.ZygoteInit.main (ZygoteInit.java:947)

signInWithEmailAndPassword. Getting a NullPointerException [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 3 years ago.
I wanted to start my new and also first app, and it crashes every time i hit the button to login. It tells me that there is a NullPointerException, but i have no clue why. Could someone help me? Have been looking for solutions but can't find any helping ones so far.
package com.glowchat.app;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
public class LoginActivity extends AppCompatActivity {
private Button loginbtn;
private EditText email;
private EditText password;
private FirebaseAuth auth;
private FirebaseUser user;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
loginbtn = (Button) findViewById(R.id.loginbtn);
loginbtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
email = (EditText) findViewById(R.id.inputEmailLogin);
password = (EditText) findViewById(R.id.inputPasswordLogin);
String loginemail = email.getText().toString();
String loginpassword = password.getText().toString();
if (loginemail.isEmpty() || loginpassword.isEmpty()) {
Toast.makeText(LoginActivity.this, "Please fill out all fields.", Toast.LENGTH_SHORT).show();
} else {
auth.signInWithEmailAndPassword(loginemail, loginpassword).addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() {
#Override
public void onComplete(#NonNull Task<AuthResult> task) {
if (task.isSuccessful()) {
Toast.makeText(LoginActivity.this, "Authentication successfull.", Toast.LENGTH_SHORT).show();
user = auth.getCurrentUser();
} else {
Toast.makeText(LoginActivity.this, "Authentication failed. Check your input and your internet connection.", Toast.LENGTH_SHORT).show();
user = null;
}
}
});
}
}
});
}
}
This is what i get in the Run tab:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.glowchat.app, PID: 29274
java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.tasks.Task com.google.firebase.auth.FirebaseAuth.signInWithEmailAndPassword(java.lang.String, java.lang.String)' on a null object reference
at com.glowchat.app.LoginActivity$1.onClick(LoginActivity.java:47)
at android.view.View.performClick(View.java:6935)
at android.widget.TextView.performClick(TextView.java:12742)
at android.view.View$PerformClick.run(View.java:26211)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:7000)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:441)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)

You just declared FirebaseAuth auth but not init it so that you can't signInWithEmailAndPassword.
I think this Firebase docs will help you a little bit.

Hot to set alarm and notification when new message arrives from Firebase Realtime Database to android Device [duplicate]

This question already has answers here:
How to sound notifications sound when new Message arrives from Firebase Realtime Data base
(4 answers)
Closed 4 years ago.
I'm using firebase data base to create my chat applicaiton. Now that I have sucessfully completed my chat application, but when new message arrives I would like to notify user with sound and NOtification in Notification bar even when the app is not running.
I used the below code to do that
NotificationCompat.Builder builder = new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.ic_launcher)
.setContentTitle("Notifications Example")
.setContentText("This is a test notification");
Intent notificationIntent = new Intent(this, MenuScreen.class);
PendingIntent contentIntent = PendingIntent.getActivity(this, 0, notificationIntent,
PendingIntent.FLAG_UPDATE_CURRENT);
builder.setContentIntent(contentIntent);
builder.setAutoCancel(true);
builder.setLights(Color.BLUE, 500, 500);
long[] pattern = {500,500,500,500,500,500,500,500,500};
builder.setVibrate(pattern);
builder.setStyle(new NotificationCompat.InboxStyle());
builder.setSound(Settings.System.DEFAULT_NOTIFICATION_URI)
NotificationManager manager = (NotificationManager)
getSystemService(Context.NOTIFICATION_SERVICE);
manager.notify(1, builder.build());
But it only set alarm when i open the chat activity, then aftearwards when new message arrives it does nothing.
Here is my chat activity code
package com.nepalpolice.mnemonics.chat;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.Color;
import android.media.AudioManager;
import android.media.RingtoneManager;
import android.media.ToneGenerator;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.Uri;
import android.os.Bundle;
import android.os.Vibrator;
import android.provider.Settings;
import android.support.annotation.Nullable;
import android.support.v4.app.NotificationCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.iid.FirebaseInstanceId;
import com.google.firebase.messaging.RemoteMessage;
import com.nepalpolice.mnemonics.R;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* Created by filipp on 6/28/2016.
*/
public class Chat_Room extends AppCompatActivity{
private Button btn_send_msg;
private EditText input_msg;
private TextView chat_conversation;
private Toolbar mainToolbar;
private String user_name,room_name;
private DatabaseReference root ;
private String temp_key;
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.chat_room);
btn_send_msg = (Button) findViewById(R.id.btn_send);
input_msg = (EditText) findViewById(R.id.msg_input);
chat_conversation = (TextView) findViewById(R.id.textView);
user_name = getIntent().getExtras().get("user_name").toString();
room_name = getIntent().getExtras().get("room_name").toString();
mainToolbar = (Toolbar) findViewById(R.id.main_chat);
setSupportActionBar(mainToolbar);
getSupportActionBar().setTitle(" Room - "+room_name);
root = FirebaseDatabase.getInstance().getReference().child(room_name);
btn_send_msg.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Map<String,Object> map = new HashMap<String, Object>();
temp_key = root.push().getKey();
root.updateChildren(map);
DatabaseReference message_root = root.child(temp_key);
Map<String,Object> map2 = new HashMap<String, Object>();
map2.put("name",user_name);
map2.put("msg",input_msg.getText().toString());
message_root.updateChildren(map2);
input_msg.getText().clear();
}
});
root.addChildEventListener(new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
append_chat_conversation(dataSnapshot);
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
append_chat_conversation(dataSnapshot);
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
private String chat_msg,chat_user_name;
private void append_chat_conversation(DataSnapshot dataSnapshot) {
Iterator i = dataSnapshot.getChildren().iterator();
while (i.hasNext()){
chat_msg = (String) ((DataSnapshot)i.next()).getValue();
chat_user_name = (String) ((DataSnapshot)i.next()).getValue();
chat_conversation.append(chat_user_name +" : "+chat_msg +" \n");
}
}
}
Here is my Firebase Data structure file
Firebase Data Structure
Any help is appreciated. Thanks in advance.

If you are using FCM, you need to understand this part of the doc before proceeding:
The onMessageReceived is provided for most message types, with the following exceptions which are listed below:
Notification messages delivered when your app is in the background. In this case, the notification is delivered to the device’s system tray. A user tap on a notification opens the app launcher by default
Messages with both notification and data payload, both background and foreground. In this case, the notification is delivered to the device’s system tray, and the data payload is delivered in the extras of the intent of your launcher Activity.
So if you need to decide the type of payload you re sending to the android device. You may want to go for Message with both Notifications and data payload so that onMessageRecieved() is invoked at all times.
You can find more details Here

Read Write to Firebase Real time database

I have connected to Firebase shown under Save and Retrieve Data in Tools >> Firebase. My project is in android studios using Java.
This is the error I get from logcat and the code below:
12-16 11:42:42.699 2485-2550/? E/PlayCommon: [120] com.google.android.play.a.g.a(466): Failed to connect to server: java.net.UnknownHostException: Unable to resolve host "play.googleapis.com": No address associated with hostname
12-16 11:43:00.005 1534-1547/? E/memtrack: Couldn't load memtrack module
This package com.example.sammay.firebaseapplication;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
public class MainActivity extends AppCompatActivity {
EditText editTextName;
Button buttonAdd;
Spinner spinnerGenres;
DatabaseReference databaseArtist;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// databaseArtist = FirebaseDatabase.getInstance().getReference("artists");
editTextName = (EditText)findViewById(R.id.editTextName);
buttonAdd = (Button)findViewById(R.id.buttonAddArtist);
spinnerGenres = (Spinner)findViewById(R.id.spinnerGenres);
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference myRef = database.getReference("root");
myRef.setValue("Hello, World!");
buttonAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
addArtist();
}
});
}
private void addArtist(){
String name = editTextName.getText().toString().trim();
String genre = spinnerGenres.getSelectedItem().toString();
if(!TextUtils.isEmpty(name)){
String id = databaseArtist.push().getKey();
Artist artist = new Artist(id, name, genre);
databaseArtist.child(id).setValue(artist);
Toast.makeText(this, "Artist added", Toast.LENGTH_LONG).show();
}else{
Toast.makeText(this, "You should enter a name", Toast.LENGTH_LONG).show();
}
}
}
I have also created the necessary class Artist with the said details.
Everything seems to look correct but I when I launch the app and enter details and click the button nothing happens to the real-time database.

Most common reason for getting the UnknownHostException is the missing Internet-Permission in your AndroidManifest.xml file. To solve this, please add the following line of code right after your package name:
<uses-permission android:name="android.permission.INTERNET"></uses-permission>

Error while opening Android app

i am new to android development and i am writing an app for my college project .The app transmits a string of data stored in shared preferences .The data is stored by one time setup screen which is never shown again.The issue is after first time,when app is started again it shows that "app has unfortunately stopped working "and when i click ok the app starts.Can anybody tell me why this is happening?
Code:
package com.example.homeautomation.zigbeehomeauto;
import android.annotation.TargetApi;
import android.content.SharedPreferences;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.os.Build;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.Toast;
public class MainScreen extends ActionBarActivity {
NdefMessage msg;
NfcAdapter nfcadapter;
public static final String PREFS_NAME = "MyPrefsFile";
public String pass2 ;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_screen);
SharedPreferences check = getSharedPreferences(PREFS_NAME, 0);
String Pass = check.getString("Str", "Nothing");
pass2 = Pass;
nfcadapter = NfcAdapter.getDefaultAdapter(this);
if (nfcadapter == null) {
Toast.makeText(this, "NFC is not available User", Toast.LENGTH_LONG)
.show();
finish();
}
}
public void ExApp(View v) {
finish();
System.exit(0);
}
#TargetApi(Build.VERSION_CODES.JELLY_BEAN)
public void Nsend(View v)
{
byte[] stringBytes = pass2.getBytes();
nfcadapter.setNdefPushMessage(msg = new NdefMessage(new NdefRecord[]{NdefRecord.createMime("text/plain", stringBytes)
}),this);
}
}
Logcat Ouput:
04-07 12:04:38.478 10836-10836/com.example.homeautomation.zigbeehomeauto E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.homeautomation.zigbeehomeauto, PID: 10836
android.util.SuperNotCalledException: Activity {com.example.homeautomation.zigbeehomeauto/com.example.homeautomation.zigbeehomeauto.SetupScreen} did not call through to super.onCreate()
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2510)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2603)
at android.app.ActivityThread.access$900(ActivityThread.java:174)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:146)
at android.app.ActivityThread.main(ActivityThread.java:5752)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
at dalvik.system.NativeStart.main(Native Method)

Check in your SetupScreen.java do you have super.onCreate(savedInstanceState);
after onCreate() Method is starts .
post your SetupScreen.java code also ..

Your onCreate() method of class SetupScreen do not call the super.onCreate(). Add the statement and the error should go away.