How to implement a custom AlertDialog View in Android?

This example demonstrates how to implement a custom AlertDialog View 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"?>
<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">
   <Button
      android:id="@+id/buttonShowDialog"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:background="@color/colorPrimary"
      android:padding="15dp"
      android:text="Android Custom Dialog Example"
      android:textAllCaps="false"
      android:textColor="#ffffff" />
</androidx.constraintlayout.widget.ConstraintLayout>
Step 3 − Add the following code to res/layout/my_dialog.xml.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"
   android:layout_width="match_parent"
   android:layout_height="match_parent">
   <RelativeLayout
      android:layout_width="match_parent"
      android:layout_height="80dp"
      android:background="@color/colorPrimary">
      <ImageView
         android:layout_width="50dp"
         android:layout_height="50dp"
         android:layout_centerInParent="true"
         android:background="@drawable/ic_success" />
   </RelativeLayout>
   <TextView
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:text="Success"
      android:textAlignment="center"
      android:textAppearance="@style/TextAppearance.AppCompat.Headline"/>
   <TextView
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_marginTop="10dp"
      android:text="Lorem ipsum dolor sit amet, consectetur adipiscing elit.
      Nulla eu erat tincidunt lacus fermentum rutrum."
      android:textAlignment="center"
      android:textAppearance="@style/TextAppearance.AppCompat.Medium"/>
   <Button
      android:id="@+id/buttonOk"
      android:layout_width="200dp"
      android:layout_height="wrap_content"
      android:layout_gravity="center"
      android:layout_marginTop="15dp"
      android:background="@drawable/button_background"
      android:text="Ok"
      android:textColor="@color/colorPrimary" />
</LinearLayout>
Step 4 − Add the following code to res/drawable/button_background.xml.
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
   <item>
      <shape>
         <stroke android:width="2dp" android:color="@color/colorPrimary" />
         <solid android:color="@android:color/transparent" />
         <corners android:bottomLeftRadius="6dp" android:bottomRightRadius="6dp" android:topLeftRadius="6dp" android:topRightRadius="6dp" />
      </shape>
   </item>
</selector>
Step 5 − Add the following code to res/drawable/ic_success.xml.
<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
   android:height="24dp"
   android:viewportHeight="512"
   android:viewportWidth="512"
   android:width="24dp">
   <path android:fillColor="#FFFFFF" android:pathData="M468.907,214.604c-11.423,0 -20.682,9.26
      -20.682,20.682v20.831c-0.031,54.338 -21.221,105.412 -59.666,143.812c38.417,38.372
      -89.467,59.5 -143.761,59.5c-0.04,0 -0.08,0 -0.12,0C132.506,459.365 41.3,368.056 41.364,255.883c0.031,
      -54.337 21.221,-105.411 59.667,-143.813c38.417,- 38.372 89.468,-59.5 143.761,
      -59.5c0.04,0 0.08,0 0.12,0c28.672,0.016 56.49,5.942 82.68,17.611c10.436,4.65 22.659,
      -0.041 27.309,-10.474c4.648,-10.433 -0.04,-22.659 - 10.474,-27.309c-31.516,-14.043
      -64.989,-21.173 -99.492,-21.192c-0.052,0 -0.092,0 - 0.144,0c-65.329,0 -126.767,25.428
      -172.993,71.6C25.536,129.014 0.038,190.473 0,255.861c-0.037,65.386 25.389,126.874 71.599,
      173.136c46.21,46.262 107.668,71.76 173.055,71.798c0.051,0 0.092,0 0.144,0c65.329,0 126.767,
      -25.427 172.993,-71.6c46.262,-46.20971.76,-107.66871.798,-173.066v20.842C489.589,
      223.864 480.33,214.604 468.907,214.604z"/>
   <path android:fillColor="#FFFFFF" android:pathData="M505.942,39.803c-8.077,- 8.076 -21.172,-8.076
      -29.249,0L244.794,271.701l-52.609,-52.609c-8.076,-8.077 -21.172,-8.077 -29.248,0c-8.077,8.077
      -8.077,21.172 0,29.249l67.234,67.234c4.038,4.0399.332,6.058 14.625,6.058c5.293,0 10.586,-2.019 14.625,
      -6.058L505.942,69.052C514.019,60.975 514.019,47.88 505.942,39.803z"/>
</vector>
Step 6 − Add the following code to src/MainActivity.java
package com.app.sample;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class MainActivity extends AppCompatActivity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      findViewById(R.id.buttonShowDialog).setOnClickListener(new
      View.OnClickListener() {
         @Override
         public void onClick(View v) {
            showCustomDialog();
         }
      });
   }
   private void showCustomDialog() {
      ViewGroup viewGroup = findViewById(android.R.id.content);
      View dialogView = LayoutInflater.from(this).inflate(R.layout.my_dialog, viewGroup, false);
      AlertDialog.Builder builder = new AlertDialog.Builder(this);
      builder.setView(dialogView);
      AlertDialog alertDialog = builder.create();
      alertDialog.show();
   }
}
Step 7 − Add the following code to Manifests/AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.app.sample"> 
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      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>
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 the 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.