How to make custom dialog with rounded corners in android?

This example demonstrate about How to make custom dialog with rounded corners 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"
   android:id="@+id/parent"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity"
   android:gravity="center"
   android:orientation="vertical">
   <Button
      android:id="@+id/customDialog"
      android:text="Custom Dialog"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content" />
</LinearLayout>
In the above code, we have taken button. When user click on button, it will show custom dialog.
Step 3 − Add the following code to src/MainActivity.java
package com.example.andy.myapplication;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.RequiresApi;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
   @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      findViewById(R.id.customDialog).setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            final AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this,R.style.CustomAlertDialog);
            ViewGroup viewGroup = findViewById(android.R.id.content);
            View dialogView = LayoutInflater.from(v.getContext()).inflate(R.layout.customview, viewGroup, false);
            Button buttonOk=dialogView.findViewById(R.id.buttonOk);
            builder.setView(dialogView);
            final AlertDialog alertDialog = builder.create();
            buttonOk.setOnClickListener(new View.OnClickListener() {
               @Override
               public void onClick(View v) {
                  alertDialog.dismiss();
               }
            });
            alertDialog.show();
         }
      });
   }
}
To show custom dialog we have inflated a view as custom view. so create customview.xml and add the following code -
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical">
   <LinearLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:orientation="vertical"
      android:padding="16dp">
      <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="@color/colorPrimary"
         android:text="Ok"
         android:textColor="#FFF" />
   </LinearLayout>
</LinearLayout>
In the above code, we have implemented custom theme for alert dialog as shown below -
final AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this,R.style.CustomAlertDialog);
Now create a tag in res/styles.xml as shown below -
<style name="CustomAlertDialog" parent="Theme.AppCompat.Light.Dialog.Alert">
   <item name="android:windowBackground">@drawable/popup_background</item>
</style>
In the above code we have added background as popup_backround so create a draw able in drawable folder as popup_background.xml and add the following code-
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
   <solid android:color="#FFFFFF" />
   <corners android:radius="6dp" />
</shape>
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 −
In the above result, it shown initial screen. Now click on button it will open custom dialog with rounded corners as shown below -
Click here to download the project code