My first Chatter

MainActivity.java
======================
package com.example.zeevm.mygroupchat;

import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

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.database.ValueEventListener;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    EditText myMsg;
    String chatNode="message";
    String messageHold="";
    List<String> msgList;
    Context context;
    ListView myMsgList;

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

    private void setPointer()
    {
        myMsg=(EditText)findViewById(R.id.helloMsg);
        this.context=this;
        msgList=new ArrayList<>();
        myMsgList=(ListView)findViewById(R.id.msgList);
    }

    //sending message to our firebase
    public void sendMsg(View view)
    {
        FirebaseDatabase database=FirebaseDatabase.getInstance();
        DatabaseReference myRef = database.getReference(chatNode);
        String myString = myMsg.getText().toString();
        myRef.setValue("(zeev) "+myString);
        myMsg.setText("");
    }

        private void listenMessage()
    {
        FirebaseDatabase database = FirebaseDatabase.getInstance();
        DatabaseReference myRef = database.getReference(chatNode);
        myRef.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                messageHold=dataSnapshot.getValue(String.class);
                Toast.makeText(context, messageHold, Toast.LENGTH_SHORT).show();
                msgList.add(messageHold);
                //display in listView
                MsgAdapter msgAdapter=new MsgAdapter(context,msgList);
                myMsgList.setAdapter(msgAdapter);
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                Toast.makeText(context, "Error accord", Toast.LENGTH_SHORT).show();
            }
        });

    }


}


activity_main.xml
====================
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Message...."
        android:id="@+id/helloMsg"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="SEND MESSAGE..."
        android:onClick="sendMsg"
        android:background="#009fff"
        android:textColor="#fff" />
    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/msgList"></ListView>
</LinearLayout>

PROJECT GRADLE
==================================
// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.2.2'
        classpath 'com.google.gms:google-services:3.0.0'
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}


APP GRADLE
=====================
apply plugin: 'com.android.application'

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.0"
    defaultConfig {
        applicationId "com.example.zeevm.mygroupchat"
        minSdkVersion 19
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.0.0'
    testCompile 'junit:junit:4.12'
    compile 'com.google.firebase:firebase-core:9.0.2'
    compile 'com.google.firebase:firebase-database:9.0.2'
}
apply plugin: 'com.google.gms.google-services'



manifest.xml
================
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.zeevm.mygroupchat">

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>