How to create blur activity background in android?

This example demonstrate about How to create blue activity background in android.

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version = "1.0" encoding = "utf-8"?>
<LinearLayout 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:gravity = "center"
   android:layout_height = "match_parent"
   tools:context = ".MainActivity"
   android:background = "@drawable/ic_launcher_background"
   android:orientation = "vertical">
   <TextView
      android:id = "@+id/text"
      android:textSize = "30sp"
      android:layout_width = "wrap_content"
      android:layout_height = "wrap_content" />
</LinearLayout>

In the above code, we have taken text view to show sample text.

Step 3 − Add the following code to src/MainActivity.java

package com.example.myapplication;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.RequiresApi;
import android.support.v7.app.AppCompatActivity;
import android.telephony.TelephonyManager;
import android.view.WindowManager;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
   private static final int PERMISSION_REQUEST_CODE = 100;
   TextView textView;
   TelephonyManager telephonyManager;
   @RequiresApi(api = Build.VERSION_CODES.P)
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      getWindow().setFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND,
      WindowManager.LayoutParams.FLAG_BLUR_BEHIND);
      setContentView(R.layout.activity_main);
      textView = findViewById(R.id.text);
      textView.setText("Blur Behind Flag");
   }
}

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run  icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen –

Click here to download the project code