Messages are not displaying.

[Vibhanshu09]

After using this code, no any messages are visible.

here is my MainActivity.java code

/**

• Copyright Google Inc. All Rights Reserved.
• Licensed under the Apache License, Version 2.0 (the "License");
• you may not use this file except in compliance with the License.
• You may obtain a copy of the License at
• http://www.apache.org/licenses/LICENSE-2.0
• Unless required by applicable law or agreed to in writing, software
• distributed under the License is distributed on an "AS IS" BASIS,
• WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
• See the License for the specific language governing permissions and
• limitations under the License. */ package com.google.firebase.udacity.friendlychat;

import android.content.Intent; import android.os.Bundle; import android.support.annotation.NonNull; import android.support.v7.app.AppCompatActivity; import android.text.Editable; import android.text.InputFilter; import android.text.TextWatcher; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.ImageButton; import android.widget.ListView; import android.widget.ProgressBar; import android.widget.Toast;

import com.firebase.ui.auth.AuthUI; import com.google.firebase.auth.FirebaseAuth; import com.google.firebase.auth.FirebaseUser; 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 java.util.ArrayList; import java.util.List;

public class MainActivity extends AppCompatActivity {

private static final String TAG = "MainActivity";

public static final String ANONYMOUS = "anonymous";
public static final int DEFAULT_MSG_LENGTH_LIMIT = 1000;
public static final int RC_SIGN_IN = 1;

private ListView mMessageListView;
private MessageAdapter mMessageAdapter;
private ProgressBar mProgressBar;
private ImageButton mPhotoPickerButton;
private EditText mMessageEditText;
private Button mSendButton;

private FirebaseDatabase mFirebaseDatabase;
private DatabaseReference mMessagesDatabaseReference;
private ChildEventListener mChildEventListener;
private FirebaseAuth mFirebaseAuth;
private FirebaseAuth.AuthStateListener mAuthStateListener;
private String mUsername;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mUsername = ANONYMOUS;

    //Initialising FirebaseDatabase instance
    mFirebaseDatabase = FirebaseDatabase.getInstance();
    //Initialising FirebaseAuth instance
    mFirebaseAuth = FirebaseAuth.getInstance();
    mMessagesDatabaseReference = mFirebaseDatabase.getReference().child("message");

    // Initialize references to views
    mProgressBar = (ProgressBar) findViewById(R.id.progressBar);
    mMessageListView = (ListView) findViewById(R.id.messageListView);
    mPhotoPickerButton = (ImageButton) findViewById(R.id.photoPickerButton);
    mMessageEditText = (EditText) findViewById(R.id.messageEditText);
    mSendButton = (Button) findViewById(R.id.sendButton);

    // Initialize message ListView and its adapter
    List<FriendlyMessage> friendlyMessages = new ArrayList<>();
    mMessageAdapter = new MessageAdapter(this, R.layout.item_message, friendlyMessages);
    mMessageListView.setAdapter(mMessageAdapter);

    // Initialize progress bar
    mProgressBar.setVisibility(ProgressBar.INVISIBLE);

    // ImagePickerButton shows an image picker to upload a image for a message
    mPhotoPickerButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            // TODO: Fire an intent to show an image picker
        }
    });

    // Enable Send button when there's text to send
    mMessageEditText.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
        }

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
            if (charSequence.toString().trim().length() > 0) {
                mSendButton.setEnabled(true);
            } else {
                mSendButton.setEnabled(false);
            }
        }

        @Override
        public void afterTextChanged(Editable editable) {
        }
    });
    mMessageEditText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(DEFAULT_MSG_LENGTH_LIMIT)});

    // Send button sends a message and clears the EditText
    mSendButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            // Send messages on click

            FriendlyMessage friendlyMessage = new FriendlyMessage(mMessageEditText.getText().toString(), mUsername, null);
            mMessagesDatabaseReference.push().setValue(friendlyMessage);
            // Clear input box
            mMessageEditText.setText("");
        }
    });

    mAuthStateListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user != null) {
                onSignedInInitialize(user.getDisplayName());
            }else {
                onSignedOutCleanup();
                startActivityForResult(
                        AuthUI.getInstance()
                                .createSignInIntentBuilder()
                                .setIsSmartLockEnabled(false)
                                .setProviders(
                                        AuthUI.EMAIL_PROVIDER,
                                        AuthUI.GOOGLE_PROVIDER)
                                .build(),
                        RC_SIGN_IN);
            }
        }
    };
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    //super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == RC_SIGN_IN){
        if (resultCode == RESULT_OK){
            Toast.makeText(MainActivity.this,"Good To go",Toast.LENGTH_SHORT).show();
        }
        else {
            Toast.makeText(MainActivity.this,"Login Error",Toast.LENGTH_SHORT).show();
            finish();
        }
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.main_menu, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    return super.onOptionsItemSelected(item);
}

@Override
protected void onResume() {
    super.onResume();
    mFirebaseAuth.addAuthStateListener(mAuthStateListener);
}

@Override
protected void onPause() {
    super.onPause();
    if (mAuthStateListener != null) {
        mFirebaseAuth.removeAuthStateListener(mAuthStateListener);
    }
    mMessageAdapter.clear();
    detachDatabaseReadListener();
}

private void onSignedInInitialize(String username){
    mUsername = username;
    attachDatabaseReadListener();
}
private void onSignedOutCleanup(){
    mUsername = ANONYMOUS;
    mMessageAdapter.clear();
    detachDatabaseReadListener();
}
private void attachDatabaseReadListener(){
    if (mChildEventListener == null) {
        mChildEventListener = new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                FriendlyMessage friendlyMessage = dataSnapshot.getValue(FriendlyMessage.class);
                mMessageAdapter.add(friendlyMessage);
            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {
            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {
            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
            }
        };
        mMessagesDatabaseReference.addChildEventListener(mChildEventListener);
    }
}
private void detachDatabaseReadListener(){
    if (mChildEventListener != null) {
        mMessagesDatabaseReference.removeEventListener(mChildEventListener);
        mChildEventListener = null;
    }
}

}

[Vibhanshu09]

Error message is : setValue at /message/-L3TyF1H0XVMvOUw6sqF failed: DatabaseError: Permission denied

and my Database rules are: { "rules": { "messages": { // only authenticated users can read and write the messages node ".read": "auth != null", ".write": "auth != null", "$id": { // the read and write rules cascade to the individual messages // messages should have a 'name' and 'text' key or a 'name' and 'photoUrl' key ".validate": "newData.hasChildren(['name', 'text']) && !newData.hasChildren(['photoUrl']) || newData.hasChildren(['name', 'photoUrl']) && !newData.hasChildren(['text'])" } } } }

[Cherudek]

Because the child is "message" mMessagesDatabaseReference = mFirebaseDatabase.getReference().child("message");

But on the Rules is: "messages"

[goyalankit021]

Make sure your device is connected with internet

[shakoorsherani]

the user sending the message is not authenticated change the rules to ".read": true, ".write": true the messages will appear after this change the error is saying that the user sending the message is not authorized and that the database has denied his permission to write to the database