I was using the chat room from this link in my app.
https://gist.github.com/puf/f49a1b07e92952b44f2dc36d9af04e3c
My app flow:
Login -> MainActivity -> select a team from listview to join chat -> ChatRoomActivity
My problem is when i clicked on one of the team in my listview, it crashes. My code for the chatroom is exactly the same as the link, except i changed MainActivity to ChatRoomActivity and removed the login popup. The rest stays the same.Can someone help me correct it or identify the cause?
MainActivity:
public class MainActivity extends AppCompatActivity {
public static final String TEAM_NAME = "com.example.user.stfv2.teamname";
public static final String TEAM_ID = "com.example.user.stfv2.teamid";
private FirebaseAuth firebaseAuth;
EditText editTextName;
EditText textDate;
EditText textTime;
Spinner spinnerSport;
Button buttonAddTeam;
ListView listViewTeams;
DatePickerDialog datePickerDialog;
List<Team> teams;
DatabaseReference databaseTeams;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
firebaseAuth = FirebaseAuth.getInstance();
if(firebaseAuth.getCurrentUser() == null){
finish();
startActivity(new Intent(this, SignInActivity.class));
}
FirebaseUser user = firebaseAuth.getCurrentUser();
databaseTeams = FirebaseDatabase.getInstance().getReference("teams");
editTextName = (EditText) findViewById(R.id.editTextName);
spinnerSport = (Spinner) findViewById(R.id.spinnerSports);
listViewTeams = (ListView) findViewById(R.id.listViewTeams);
textDate = (EditText) findViewById(R.id.textDate);
textTime = (EditText) findViewById(R.id.textTime);
buttonAddTeam = (Button) findViewById(R.id.buttonAddTeam);
teams = new ArrayList<>();
buttonAddTeam.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent myIntent = new Intent(MainActivity.this,
AddActivity.class);
startActivity(myIntent);
}
});
listViewTeams.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Team team = teams.get(i);
Intent intent = new Intent(getApplicationContext(), ChatRoomActivity.class);
intent.putExtra(TEAM_ID, team.getTeamId());
intent.putExtra(TEAM_NAME, team.getTeamName());
startActivity(intent);
}
});
listViewTeams.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
Team team = teams.get(i);
showUpdateDeleteDialog(team.getTeamId(), team.getTeamName());
return true;
}
});
}
private void showUpdateDeleteDialog(final String teamId, String teamName) {
AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this);
LayoutInflater inflater = getLayoutInflater();
final View dialogView = inflater.inflate(R.layout.update_dialog, null);
dialogBuilder.setView(dialogView);
final EditText editTextName = (EditText) dialogView.findViewById(R.id.editTextName);
final Spinner spinnerSport = (Spinner) dialogView.findViewById(R.id.spinnerSports);
final Button buttonUpdate = (Button) dialogView.findViewById(R.id.buttonUpdateTeam);
final Button buttonDelete = (Button) dialogView.findViewById(R.id.buttonDeleteTeam);
final EditText textDate = (EditText) dialogView.findViewById(R.id.textDate);
final EditText textTime = (EditText) dialogView.findViewById(R.id.textTime);
dialogBuilder.setTitle(teamName);
final AlertDialog b = dialogBuilder.create();
b.show();
textDate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final Calendar c = Calendar.getInstance();
int mYear = c.get(Calendar.YEAR);
int mMonth = c.get(Calendar.MONTH);
int mDay = c.get(Calendar.DAY_OF_MONTH);
datePickerDialog = new DatePickerDialog(MainActivity.this,
new DatePickerDialog.OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year,
int monthOfYear, int dayOfMonth) {
textDate.setText(dayOfMonth + "/"
+ (monthOfYear + 1) + "/" + year);
}
}, mYear, mMonth, mDay);
datePickerDialog.show();
}
});
textTime.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Calendar mcurrentTime = Calendar.getInstance();
int hour = mcurrentTime.get(Calendar.HOUR_OF_DAY);
int minute = mcurrentTime.get(Calendar.MINUTE);
TimePickerDialog mTimePicker;
mTimePicker = new TimePickerDialog(MainActivity.this, new TimePickerDialog.OnTimeSetListener() {
@Override
public void onTimeSet(TimePicker timePicker, int selectedHour, int selectedMinute) {
textTime.setText(selectedHour + ":" + selectedMinute);
}
}, hour, minute, true);
mTimePicker.setTitle("Select Time");
mTimePicker.show();
}
});
buttonUpdate.setOnClickListener(new View.OnClickListener() {
FirebaseUser user = firebaseAuth.getCurrentUser();
@Override
public void onClick(View view) {
String name = editTextName.getText().toString().trim();
String sport = spinnerSport.getSelectedItem().toString();
String owner = user.getUid();
String date = textDate.getText().toString();
String time = textTime.getText().toString();
if (!TextUtils.isEmpty(name)) {
updateTeam(teamId, name, sport, owner, date, time);
b.dismiss();
}
}
});
buttonDelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
deleteTeam(teamId);
b.dismiss();
}
});
}
private boolean updateTeam(String id, String name, String sport, String owner, String date, String time) {
DatabaseReference dR = FirebaseDatabase.getInstance().getReference("teams").child(id);
Team team = new Team(id, name, sport, owner, date, time);
dR.setValue(team);
Toast.makeText(getApplicationContext(), "Team Updated", Toast.LENGTH_LONG).show();
return true;
}
private boolean deleteTeam(String id) {
DatabaseReference dR = FirebaseDatabase.getInstance().getReference("teams").child(id);
dR.removeValue();
DatabaseReference drTracks = FirebaseDatabase.getInstance().getReference("tracks").child(id);
drTracks.removeValue();
Toast.makeText(getApplicationContext(), "Team Deleted", Toast.LENGTH_LONG).show();
return true;
}
@Override
protected void onStart() {
super.onStart();
databaseTeams.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
teams.clear();
for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
Team team = postSnapshot.getValue(Team.class);
teams.add(team);
}
TeamList teamAdapter = new TeamList(MainActivity.this, teams);
listViewTeams.setAdapter(teamAdapter);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_logout:
firebaseAuth.signOut();
finish();
startActivity(new Intent(this, SignInActivity.class));
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
Logcat:
03-19 01:40:25.709 2995-2995/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.user.stfv2, PID: 2995
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.user.stfv2/com.example.user.stfv2.ChatRoomActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.example.user.stfv2.ChatRoomActivity.setUsername(ChatRoomActivity.java:58)
at com.example.user.stfv2.ChatRoomActivity.onCreate(ChatRoomActivity.java:73)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Edit 1:
layout_chat_room:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.user.stfv2.MainActivity">
<RelativeLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/header"
android:gravity="end">
<ImageView
android:layout_width="36dp"
android:layout_height="36dp"
android:id="@+id/userIcon"
android:foregroundGravity="center"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true" />
<TextView
android:layout_width="141dp"
android:layout_height="wrap_content"
android:id="@+id/usernameTxt"
android:layout_toRightOf="@+id/userIcon"
android:layout_alignTop="@+id/userIcon"
android:layout_alignBottom="@+id/userIcon"
android:gravity="center_vertical"
tools:text="Username"
android:layout_weight="0" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Sign in"
android:id="@+id/loginBtn"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Sign out"
android:id="@+id/logoutBtn"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true" />
</RelativeLayout>
<android.support.v7.widget.RecyclerView
android:id="@+id/messagesList"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
tools:listitem="@android:layout/two_line_list_item"
android:layout_above="@+id/footer"
android:layout_below="@+id/header" />
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:id="@+id/footer">
<ImageButton
android:layout_width="36dp"
android:layout_height="36dp"
android:id="@+id/imageBtn"
android:background="@android:drawable/ic_menu_gallery" />
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/messageTxt"
android:layout_gravity="bottom"
android:layout_weight="1"
android:inputType="textShortMessage|textAutoCorrect" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Send"
android:id="@+id/sendBtn"
android:layout_gravity="bottom" />
</LinearLayout>
</RelativeLayout>
ChatRoomActivity:
public class ChatRoomActivity extends AppCompatActivity {
private static final String TAG = "ChatRoomActivity";
static final int RC_PHOTO_PICKER = 1;
private Button sendBtn;
private EditText messageTxt;
private RecyclerView messagesList;
private ChatMessageAdapter adapter;
private ImageButton imageBtn;
private TextView usernameTxt;
private View loginBtn;
private View logoutBtn;
private FirebaseApp app;
private FirebaseDatabase database;
private FirebaseAuth auth;
private FirebaseStorage storage;
private DatabaseReference databaseRef;
private StorageReference storageRef;
private String username;
private void setUsername(String username) {
Log.d(TAG, "setUsername("+String.valueOf(username)+")");
if (username == null) {
username = "Android";
}
boolean isLoggedIn = !username.equals("Android");
this.username = username;
this.usernameTxt.setText(username);
this.logoutBtn.setVisibility(isLoggedIn ? View.VISIBLE : View.GONE);
this.loginBtn .setVisibility(isLoggedIn ? View.GONE : View.VISIBLE);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sendBtn = (Button) findViewById(R.id.sendBtn);
messageTxt = (EditText) findViewById(R.id.messageTxt);
messagesList = (RecyclerView) findViewById(R.id.messagesList);
imageBtn = (ImageButton) findViewById(R.id.imageBtn);
loginBtn = findViewById(R.id.loginBtn);
logoutBtn = findViewById(R.id.logoutBtn);
usernameTxt = (TextView) findViewById(R.id.usernameTxt);
setUsername("Android");
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
messagesList.setHasFixedSize(false);
messagesList.setLayoutManager(layoutManager);
// Show an image picker when the user wants to upload an imasge
imageBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("image/jpeg");
intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
startActivityForResult(Intent.createChooser(intent, "Complete action using"), RC_PHOTO_PICKER);
}
});
// Show a popup when the user asks to sign in
loginBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
LoginDialog.showLoginPrompt(ChatRoomActivity.this, app);
}
});
// Allow the user to sign out
logoutBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
auth.signOut();
}
});
adapter = new ChatMessageAdapter(this);
messagesList.setAdapter(adapter);
adapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
public void onItemRangeInserted(int positionStart, int itemCount) {
messagesList.smoothScrollToPosition(adapter.getItemCount());
}
});
// Get the Firebase app and all primitives we'll use
app = FirebaseApp.getInstance();
database = FirebaseDatabase.getInstance(app);
auth = FirebaseAuth.getInstance(app);
storage = FirebaseStorage.getInstance(app);
// Get a reference to our chat "room" in the database
databaseRef = database.getReference("chat");
sendBtn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
ChatMessage chat = new ChatMessage(username, messageTxt.getText().toString());
// Push the chat message to the database
databaseRef.push().setValue(chat);
messageTxt.setText("");
}
});
// Listen for when child nodes get added to the collection
databaseRef.addChildEventListener(new ChildEventListener() {
public void onChildAdded(DataSnapshot snapshot, String s) {
// Get the chat message from the snapshot and add it to the UI
ChatMessage chat = snapshot.getValue(ChatMessage.class);
adapter.addMessage(chat);
}
public void onChildChanged(DataSnapshot dataSnapshot, String s) { }
public void onChildRemoved(DataSnapshot dataSnapshot) { }
public void onChildMoved(DataSnapshot dataSnapshot, String s) { }
public void onCancelled(DatabaseError databaseError) { }
});
// When the user has entered credentials in the login dialog
LoginDialog.onCredentials(new OnSuccessListener<LoginDialog.EmailPasswordResult>() {
public void onSuccess(LoginDialog.EmailPasswordResult result) {
// Sign the user in with the email address and password they entered
auth.signInWithEmailAndPassword(result.email, result.password);
}
});
// When the user signs in or out, update the username we keep for them
auth.addAuthStateListener(new FirebaseAuth.AuthStateListener() {
public void onAuthStateChanged(FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser() != null) {
// User signed in, set their email address as the user name
setUsername(firebaseAuth.getCurrentUser().getEmail());
}
else {
// User signed out, set a default username
setUsername("Android");
}
}
});
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == RC_PHOTO_PICKER && resultCode == RESULT_OK) {
Uri selectedImageUri = data.getData();
// Get a reference to the location where we'll store our photos
storageRef = storage.getReference("chat_photos");
// Get a reference to store file at chat_photos/<FILENAME>
final StorageReference photoRef = storageRef.child(selectedImageUri.getLastPathSegment());
// Upload file to Firebase Storage
photoRef.putFile(selectedImageUri)
.addOnSuccessListener(this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
// When the image has successfully uploaded, we get its download URL
Uri downloadUrl = taskSnapshot.getDownloadUrl();
// Set the download URL to the message box, so that the user can send it to the database
messageTxt.setText(downloadUrl.toString());
}
});
}
}
}
Your problem is that you are defining the wrong XML file. When you used the code from ChatroomActivity, you forgot to change the XML file. It is currently set to setContentView(R.layout.activity_main), but it should be setContentView(R.layout.layout_chat_room).