Notification_FireBase (Generate Notification through FireBase)

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

AndroidManifest.xml

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

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Notification_FireBase"
        tools:targetApi="31">

        <meta-data
            android:name="com.google.firebase.messaging.default_notification_icon"
            android:resource="@drawable/ic_launcher_foreground" />
        <!-- Set color used with incoming notification messages. This is used when no color is set for the incoming
             notification message. See README(https://goo.gl/6BKBk7) for more. -->
        <meta-data
            android:name="com.google.firebase.messaging.default_notification_color"
            android:resource="@color/purple_700" />

        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

build.gradle

plugins {
    id 'com.android.application'
    id 'org.jetbrains.kotlin.android'
    id 'com.google.gms.google-services'
}

android {
    compileSdk 32

    defaultConfig {
        applicationId "com.example.notification_firebase"
        minSdk 21
        targetSdk 32
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
}

dependencies {

    implementation 'androidx.core:core-ktx:1.7.0'
    implementation 'androidx.appcompat:appcompat:1.4.2'
    implementation 'com.google.android.material:material:1.6.1'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
    implementation 'com.google.firebase:firebase-messaging:20.1.0'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
}

MainActivity.kt

package com.example.notification_firebase

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.notification)
    }
}

MyFirebaseMessagingService.kt

package com.example.notification_firebase

import android.app.NotificationChannel
import android.app.NotificationManager
import android.app.PendingIntent
import android.content.Context
import android.content.Intent
import android.os.Build
import android.widget.RemoteViews
import androidx.core.app.NotificationCompat
import com.google.firebase.messaging.FirebaseMessagingService
import com.google.firebase.messaging.RemoteMessage

const val channelId = "notification_channel"
const val channelName = "com.example.firebase_notification"

//extends from FirebaseMessaging Service
class MyFirebaseMessagingService : FirebaseMessagingService() {

    //generate the notification
    //attach the notification with the custom layout
    //show the notification


    //receive the notification having remoteView
    override fun onMessageReceived(remoteMessage: RemoteMessage) {
        
        //if it is not null it will call generateNotification
       if(remoteMessage.getNotification() != null) {
           generateNotification(remoteMessage.notification!!.title!!,remoteMessage.notification!!.body!!)
       }
    }
//RemoteView Creation and
    fun getRemoteView(title: String, message: String): RemoteViews {
        val remoteViews = RemoteViews("com.example.notification_firebase", R.layout.notification)

    //and set Text and Title
        remoteViews.setTextViewText(R.id.title, title)
        remoteViews.setTextViewText(R.id.message, message)
        remoteViews.setImageViewResource(R.id.app_logo, R.drawable.applogo)

        return remoteViews
    }

    //create a method to generate notification which takes title and message
    fun generateNotification(title: String, message: String) {

        //create intent when user click on notification, he redirect on the app
        val intent = Intent(this, MainActivity::class.java)
        //clear all the activities and put this activity on top for this we need pendindIntent
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)


        //create pending activity it call only once when user click on the notification after it will destroy
        val pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_ONE_SHOT)


        //build the notification
        var builder: NotificationCompat.Builder =
            NotificationCompat.Builder(applicationContext, channelId)
                //set the properties of notification
                .setSmallIcon(R.drawable.app_logo)
                .setAutoCancel(true)
                .setVibrate(longArrayOf(1000, 1000, 1000, 1000))
                .setOnlyAlertOnce(true)
                .setContentIntent(pendingIntent)

//attach builder to remoteView so we need to build remoteView on top of the class
        builder = builder.setContent(getRemoteView(title, message))


//build notification manager
        val notificationManager =
            getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
//check this version is greater than oreo or not
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {

            //create notification channel
            val notificationChannel =
                NotificationChannel(channelId, channelName, NotificationManager.IMPORTANCE_HIGH)
            notificationManager.createNotificationChannel(notificationChannel)


        }
        //then notifiy it
        notificationManager.notify(0,builder.build())
    }
}

notification.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <RelativeLayout
        android:layout_width="match_parent"
        android:padding="10dp"
        android:layout_height="wrap_content">



        <ImageView
            android:id="@+id/app_logo"
            android:layout_width="70dp"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="10dp"
            android:layout_height="70dp"
            android:src="@drawable/applogo"/>

        <TextView
            android:id="@+id/title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:layout_marginTop="15dp"
            android:layout_toRightOf="@+id/app_logo"
            android:hint="Title"
            android:textSize="20sp"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/message"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/title"
            android:layout_marginTop="10dp"
            android:layout_toRightOf="@+id/app_logo"
            android:hint="This is a Message"
            android:textSize="20sp"
            android:textStyle="bold"
            android:layout_marginLeft="10dp"

            />

    </RelativeLayout>

</RelativeLayout>

Reference Link -

https://www.youtube.com/watch?v=2xoJi-ZHmNI&t=1836s&ab_channel=GeeksforGeeks

https://www.geeksforgeeks.org/how-to-push-notification-in-android-using-firebase-cloud-messaging/