I'll provide a comprehensive step-by-step guide on converting a website into an Android app using Android Studio, including all the requested features. Let's get started.

Step 1: Set Up a New Android Studio Project

1. Open Android Studio.
2. Click on "Start a new Android Studio project".
3. Select "Empty Activity" and click Next.
4. Name your application (e.g., MyWebApp).
5. Choose Java or Kotlin as the language.
6. Click Finish to create your project.

Step 2: Add WebView to Load Website

Modify AndroidManifest.xml

1. Open AndroidManifest.xml and add internet permission:

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

2. Add WebView to your activity_main.xml:

   <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">
   
       <WebView
           android:id="@+id/webView"
           android:layout_width="match_parent"
           android:layout_height="match_parent" />
   </androidx.constraintlayout.widget.ConstraintLayout>
   

Modify MainActivity.java

package com.example.mywebapp;

import android.annotation.SuppressLint;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.view.View;
import android.webkit.WebChromeClient;
import android.webkit.WebResourceRequest;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ProgressBar;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private WebView webView;
    private ProgressBar progressBar;

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

        webView = findViewById(R.id.webView);
        progressBar = findViewById(R.id.progressBar);

        WebSettings webSettings = webView.getSettings();
        webSettings.setJavaScriptEnabled(true);
        webSettings.setDomStorageEnabled(true);

        webView.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
                view.loadUrl(request.getUrl().toString());
                return true;
            }

            @Override
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                progressBar.setVisibility(View.VISIBLE);
            }

            @Override
            public void onPageFinished(WebView view, String url) {
                progressBar.setVisibility(View.GONE);
            }
        });

        webView.setWebChromeClient(new WebChromeClient());
        webView.loadUrl("https://www.example.com"); // Replace with your website URL
    }

    @Override
    public void onBackPressed() {
        if (webView.canGoBack()) {
            webView.goBack();
        } else {
            super.onBackPressed();
        }
    }
}

Step 3: Add Splash Screen

1. Create a new SplashActivity.java file:

   package com.example.mywebapp;
   
   import android.content.Intent;
   import android.os.Bundle;
   import android.os.Handler;
   import androidx.appcompat.app.AppCompatActivity;
   
   public class SplashActivity extends AppCompatActivity {
   
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_splash);
   
           new Handler().postDelayed(() -> {
               startActivity(new Intent(SplashActivity.this, MainActivity.class));
               finish();
           }, 3000); // 3-second delay
       }
   }
   

2. Create activity_splash.xml:

   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:gravity="center"
       android:background="@color/white"
       android:orientation="vertical">
   
       <ImageView
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:src="@drawable/logo" />
   </LinearLayout>
   

3. Set SplashActivity as the launcher in AndroidManifest.xml:

   <activity android:name=".SplashActivity">
       <intent-filter>
           <action android:name="android.intent.action.MAIN"/>
           <category android:name="android.intent.category.LAUNCHER"/>
       </intent-filter>
   </activity>
   

Step 4: Add Offline Support

Modify MainActivity.java:

@Override
public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
    webView.loadUrl("file:///android_asset/offline.html");
}

Create offline.html inside assets folder:

<!DOCTYPE html>
<html>
<head>
    <title>No Internet</title>
</head>
<body>
    <h2>You are offline</h2>
    <p>Please check your internet connection.</p>
</body>
</html>

Step 5: Add Push Notifications (Firebase)

1. Add Firebase to your project from the Firebase Console.
2. Add the google-services.json file to your app.
3. Modify build.gradle (app):

   implementation 'com.google.firebase:firebase-messaging:23.0.0'
   

4. Create FirebaseMessagingService.java:

   package com.example.mywebapp;
   
   import android.app.NotificationChannel;
   import android.app.NotificationManager;
   import android.os.Build;
   import androidx.core.app.NotificationCompat;
   import com.google.firebase.messaging.FirebaseMessagingService;
   import com.google.firebase.messaging.RemoteMessage;
   
   public class MyFirebaseMessagingService extends FirebaseMessagingService {
   
       @Override
       public void onMessageReceived(RemoteMessage remoteMessage) {
           NotificationManager notificationManager =
               (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
   
           if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
               NotificationChannel channel = new NotificationChannel("default",
                       "Default Channel", NotificationManager.IMPORTANCE_HIGH);
               notificationManager.createNotificationChannel(channel);
           }
   
           NotificationCompat.Builder notificationBuilder =
                   new NotificationCompat.Builder(this, "default")
                           .setContentTitle(remoteMessage.getNotification().getTitle())
                           .setContentText(remoteMessage.getNotification().getBody())
                           .setSmallIcon(R.drawable.ic_notification)
                           .setAutoCancel(true);
   
           notificationManager.notify(1, notificationBuilder.build());
       }
   }
   

Step 6: Customize Navigation and Status Bar

Modify styles.xml:

<item name="android:statusBarColor">@color/black</item>
<item name="android:navigationBarColor">@color/black</item>

Step 7: Publishing to Google Play

1. Generate Signed APK:
   • Go to Build > Generate Signed Bundle/APK.
   • Select APK, create a new keystore, and sign your app.
2. Upload to Google Play Console:
   • Create a developer account.
   • Prepare a store listing (title, description, screenshots).
   • Upload your signed APK.
   • Set pricing, distribution, and content rating.
   • Submit for review.

This guide provides a full working solution for converting your website into an Android app. Let me know if you need more details!