وهذا ملف ال Manifest

<?xml version="1.0" encoding="utf-8"?><!-- suppress ALL -->

<manifest xmlns:android="

"

package="com.esoodevelop.genedyonlin">

<uses-permission
    android:name="android.permission.INTERNET">

</uses-permission>

<uses-permission
    android:name="android.permission.ACCESS_NETWORK_STATE">

</uses-permission>


<application
    android:allowBackup="true"
    android:icon="@mipmap/icgenedy_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/icgenedy_launcher"
    android:supportsRtl="true"
    android:theme="@style/AppTheme"
    android:fullBackupContent="@xml/backup_descriptor">
    <activity android:name=".GenedyOnlin">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".GenedyOnlin2" />
    <activity android:name=".GenedyOnlin3" />
    <activity android:name=".GenedyOnlin5" />
    <activity android:name=".MainActivity" />
    <activity android:name=".ChateRoom" />

</application>

وهذا ملف الجافا Mainactivty

package com.esoodevelop.genedyonlin;

import android.content.DialogInterface; import android.content.Intent; import android.os.Bundle; import android.support.v7.app.AlertDialog; import android.support.v7.app.AppCompatActivity; import android.text.TextUtils; import android.widget.EditText; import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

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

    AlertDialog dialog = new AlertDialog.Builder(this).create();
    final EditText editText = new EditText(this);
    dialog.setTitle("ادخل اسمك");
    dialog.setView(editText);
    dialog.setButton(DialogInterface.BUTTON_POSITIVE, "ok", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            String name = editText.getText().toString();
            if (!TextUtils.isEmpty(name)) {
                Intent intent = new Intent(MainActivity.this,ChateRoom.class);
                intent.putExtra("Name", name);
                startActivity(intent);
            }else{
                Toast.makeText(MainActivity.this, "ادخل اسمك", Toast.LENGTH_SHORT).show();
            }

        }

    });
    dialog.show();

}

}

وهذا ملف الجافا الخاص بالدردشة package com.esoodevelop.genedyonlin;

import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.ArrayAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.ListView;

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.HashMap; import java.util.Iterator; import java.util.Map;

public class ChateRoom extends AppCompatActivity {

private DatabaseReference root;
private String temp_key;
private EditText input_msg;
private ListView listView_chat;
ArrayList<String> list_chat = new ArrayList<>();
ArrayAdapter<String> arrayAdapter;
private String name;

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

    root = FirebaseDatabase.getInstance().getReference().child("MainChatRoom");


    listView_chat = (ListView) findViewById(R.id.listView_chat);
    input_msg = (EditText) findViewById(R.id.input_msg);
    Button btn_send_msg = (Button) findViewById(R.id.btn_send_msg);

    name = getIntent().getExtras().getString("Name");

    arrayAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, list_chat);
    listView_chat.setAdapter(arrayAdapter);

    btn_send_msg.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            Map<String, Object> map = new HashMap<>();
            temp_key = root.push().getKey();
            root.updateChildren(map);

            DatabaseReference message_root = root.child(temp_key);
            Map<String, Object> map2 = new HashMap<>();
            map2.put("name", name);
            map2.put("msg", input_msg.getText().toString());

            message_root.updateChildren(map2);
        }
    });


    root.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            Add_Chat(dataSnapshot);
        }

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

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

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

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

}


private void Add_Chat(DataSnapshot dataSnapshot) {

    Iterator i = dataSnapshot.getChildren().iterator();
    input_msg.setText("");
    while (i.hasNext()) {

        String chat_msg = (String) ((DataSnapshot) i.next()).getValue();
        String chat_user_name = (String) ((DataSnapshot) i.next()).getValue();

        list_chat.add(chat_user_name + " : " + chat_msg);
        arrayAdapter.notifyDataSetChanged();
        listView_chat.setSelection(list_chat.size());
    }


}

}

الرجاء المساعدة وشكرا