How to make custom dialog with rounded corners in android

What I am trying to do: I am trying to make a custom dialog in android With rounded corners.

What is happening: I am able to make custom dialog but it doesn't have rounded corners. I tried adding a selector but still I couldn't achieve rounded corners.

Below is my code for the same:

---

Java code:

private void launchDismissDlg() {
		
		dialog = new Dialog(getActivity(), android.R.style.Theme_Dialog);
		dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
		dialog.setContentView(R.layout.dlg_dismiss);
		dialog.setCanceledOnTouchOutside(true);
		
		Button btnReopenId = (Button) dialog.findViewById(R.id.btnReopenId);
		Button btnCancelId = (Button) dialog.findViewById(R.id.btnCancelId);

		btnReopenId.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				
				
				
			}
		});

		
		btnCancelId.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				
				
				
			}
		});
		dialog.setCanceledOnTouchOutside(false);
		dialog.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
		dialog.getWindow().setLayout(LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT);
		dialog.show();
		
	}

xml 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:background="@android:color/white"
    android:orientation="vertical" >

    <TableLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <TableRow
            android:id="@+id/tableRow1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dp"
            android:gravity="center" >

            <TextView
                android:id="@+id/textView1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:text="&quot;I WOULD LIKE TO DISMISS THE VENDOR&quot;"
                android:textColor="@color/col_dlg_blue_light"
                android:textSize="14sp"
                android:textStyle="bold" />
        </TableRow>

        <TableRow
            android:id="@+id/tableRow2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="5dp"
            android:gravity="center" >

            <TextView
                android:id="@+id/textView2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:text="BECAUSE"
                android:textColor="@android:color/black"
                android:textStyle="bold" />
        </TableRow>

      

        <TableRow
            android:id="@+id/tableRow4"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" >

            <Button
                android:id="@+id/btnReopenId"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:background="@color/col_dlg_green_light"
                android:text="REOPEN"
                android:padding="5dp"
                android:textSize="14sp"
                android:textColor="@android:color/white"
                android:textStyle="bold" />

            <Button
                android:id="@+id/btnCancelId"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:background="@color/col_dlg_pink_light"
                android:text="CANCEL"
                android:padding="5dp"
                android:textSize="14sp"
                android:textColor="@android:color/white"
                android:textStyle="bold" />
        </TableRow>
    </TableLayout>

</LinearLayout>

Create an XML file in drawable, say dialog_bg.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid
        android:color="@color/white"/>
    <corners
        android:radius="30dp" />
    <padding
        android:left="10dp"
        android:top="10dp"
        android:right="10dp"
        android:bottom="10dp" />
</shape>

set it as the background in your layout XML:

android:background="@drawable/dialog_bg"

Set the background of the dialog's root view to transparent, because Android puts your dialog layout within a root view that hides the corners in your custom layout.

Java:

dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

Kotlin:

dialog.window?.setBackgroundDrawable(ColorDrawable(Color.TRANSPARENT))

You need to do the following:

• Create a background with rounded corners for the Dialog's background:

   <?xml version="1.0" encoding="utf-8"?>
   <shape xmlns:android="http://schemas.android.com/apk/res/android"
   android:shape="rectangle" >
  
       <solid android:color="#fff" />
  
       <corners
           android:bottomLeftRadius="8dp"
           android:bottomRightRadius="8dp"
           android:topLeftRadius="8dp"
           android:topRightRadius="8dp" />
  
   </shape>
  

• Now in your Dialog's XML file in the root layout use that background with required margin:

   android:layout_marginLeft="20dip"
   android:layout_marginRight="20dip"
   android:background="@drawable/dialog_background"
  

• finally in the java part you need to do this:

   dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
   dialog.setContentView(layoutResId);
   View v = getWindow().getDecorView();
   v.setBackgroundResource(android.R.color.transparent);
  

This works perfectly for me.

With the Androidx library and Material Components Theme you can override the getTheme() method:

import androidx.fragment.app.DialogFragment

class RoundedDialog: DialogFragment() {

    override fun getTheme() = R.style.RoundedCornersDialog

    //....

}

with:

<style name="RoundedCornersDialog" parent="@style/Theme.MaterialComponents.Dialog">
    <item name="dialogCornerRadius">16dp</item>
</style>

Or you can use the MaterialAlertDialogBuilder included in the Material Components Library:

import androidx.fragment.app.DialogFragment
import com.google.android.material.dialog.MaterialAlertDialogBuilder

class RoundedAlertDialog : DialogFragment() {

    //...

    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        return MaterialAlertDialogBuilder(requireActivity(), R.style.MaterialAlertDialog_rounded)
                .setTitle("Test")
                .setMessage("Message")
                .setPositiveButton("OK", null)
                .create()
    }

}

with:

<style name="MaterialAlertDialog_rounded" parent="@style/ThemeOverlay.MaterialComponents.MaterialAlertDialog">
    <item name="shapeAppearanceOverlay">@style/DialogCorners</item>
</style>

<style name="DialogCorners">
    <item name="cornerFamily">rounded</item>
    <item name="cornerSize">16dp</item>
</style>

If you don't need a DialogFragment just use the MaterialAlertDialogBuilder.

dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

this works for me

Setting

dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

will prevent dialog to cast a shadow.

Solution is to use

dialog.getWindow().setBackgroundDrawableResource(R.drawable.dialog_rounded_background);

where is R.drawable.dialog_rounded_background

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <item>
        <shape android:shape="rectangle" android:padding="10dp">
            <solid
                android:color="@color/dialog_bg_color"/>
            <corners
                android:radius="30dp" />
        </shape>
    </item>

</layer-list>

If you use Material Components:

CustomDialog.kt

class CustomDialog: DialogFragment() {

    override fun getTheme() = R.style.RoundedCornersDialog

}

styles.xml

<style name="RoundedCornersDialog" parent="Theme.MaterialComponents.Dialog">
    <item name="dialogCornerRadius">dimen</item>
</style>

dimen.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <integer name="weight">1</integer>

    <dimen name="dialog_top_radius">21dp</dimen>

    <dimen name="textview_dialog_head_min_height">50dp</dimen>
    <dimen name="textview_dialog_drawable_padding">5dp</dimen>

    <dimen name="button_dialog_layout_margin">3dp</dimen>


</resources>

styles.xml

<style name="TextView.Dialog">
        <item name="android:paddingLeft">@dimen/dimen_size</item>
        <item name="android:paddingRight">@dimen/dimen_size</item>
        <item name="android:gravity">center_vertical</item>
        <item name="android:textColor">@color/black</item>
    </style>

    <style name="TextView.Dialog.Head">
        <item name="android:minHeight">@dimen/textview_dialog_head_min_height</item>
        <item name="android:textColor">@color/white</item>
        <item name="android:background">@drawable/dialog_title_style</item>
        <item name="android:drawablePadding">@dimen/textview_dialog_drawable_padding</item>
    </style>

    <style name="TextView.Dialog.Text">
        <item name="android:textAppearance">@style/Font.Medium.16</item>
    </style>

    <style name="Button" parent="Base.Widget.AppCompat.Button">
        <item name="android:layout_height">@dimen/button_min_height</item>
        <item name="android:layout_width">match_parent</item>
        <item name="android:textColor">@color/white</item>
        <item name="android:gravity">center</item>
        <item name="android:textAppearance">@style/Font.Medium.20</item>
    </style>

 <style name="Button.Dialog">
        <item name="android:layout_weight">@integer/weight</item>
        <item name="android:layout_margin">@dimen/button_dialog_layout_margin</item>
    </style>

    <style name="Button.Dialog.Middle">
        <item name="android:background">@drawable/button_primary_selector</item>
    </style>

dialog_title_style.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">

    <gradient
        android:angle="270"
        android:endColor="@color/primaryDark"
        android:startColor="@color/primaryDark" />

    <corners
        android:topLeftRadius="@dimen/dialog_top_radius"
        android:topRightRadius="@dimen/dialog_top_radius" />

</shape>

dialog_background.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="@color/backgroundDialog" />
    <corners
        android:topLeftRadius="@dimen/dialog_top_radius"
        android:topRightRadius="@dimen/dialog_top_radius" />
    <padding />
</shape>

dialog_one_button.xml

<?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="wrap_content"
    android:background="@drawable/dailog_background"
    android:orientation="vertical">

    <TextView
        android:id="@+id/dialogOneButtonTitle"
        style="@style/TextView.Dialog.Head"
        android:text="Process Completed" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:orientation="vertical">

        <TextView
            android:id="@+id/dialogOneButtonText"
            style="@style/TextView.Dialog.Text"
            android:text="Return the main menu" />

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <Button
                android:id="@+id/dialogOneButtonOkButton"
                style="@style/Button.Dialog.Middle"
                android:text="Ok" />

        </LinearLayout>

    </LinearLayout>

</LinearLayout>

OneButtonDialog.java

package com.example.sametoztoprak.concept.dialogs;

import android.app.Dialog;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.TextView;

import com.example.sametoztoprak.concept.R;
import com.example.sametoztoprak.concept.models.DialogFields;

/**
 * Created by sametoztoprak on 26/09/2017.
 */

public class OneButtonDialog extends Dialog implements View.OnClickListener {

    private static OneButtonDialog oneButtonDialog;
    private static DialogFields dialogFields;

    private Button dialogOneButtonOkButton;
    private TextView dialogOneButtonText;
    private TextView dialogOneButtonTitle;

    public OneButtonDialog(AppCompatActivity activity) {
        super(activity);
    }

    public static OneButtonDialog getInstance(AppCompatActivity activity, DialogFields dialogFields) {
        OneButtonDialog.dialogFields = dialogFields;
        return oneButtonDialog = (oneButtonDialog == null) ? new OneButtonDialog(activity) : oneButtonDialog;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.dialog_one_button);
        getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

        dialogOneButtonTitle = (TextView) findViewById(R.id.dialogOneButtonTitle);
        dialogOneButtonText = (TextView) findViewById(R.id.dialogOneButtonText);
        dialogOneButtonOkButton = (Button) findViewById(R.id.dialogOneButtonOkButton);

        dialogOneButtonOkButton.setOnClickListener(this);
    }

    @Override
    protected void onStart() {
        super.onStart();
        dialogOneButtonTitle.setText(dialogFields.getTitle());
        dialogOneButtonText.setText(dialogFields.getText());
        dialogOneButtonOkButton.setText(dialogFields.getOneButton());
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.dialogOneButtonOkButton:

                break;
            default:
                break;
        }
        dismiss();
    }
}

I made a new way without having a background drawable is that make it have CardView as parent and give it a app:cardCornerRadius="20dp" and then add this in the java class dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

It's another way to make it .

You can simply use MaterialAlertDialogBuilder to create custom dialog with rounded corners.

First create a style for the material dialog like this :

<style name="MyRounded.MaterialComponents.MaterialAlertDialog" parent="@style/ThemeOverlay.MaterialComponents.MaterialAlertDialog">
    <item name="shapeAppearanceOverlay">@style/ShapeAppearanceOverlay.App.CustomDialog.Rounded
    </item>
    <item name="colorSurface">@color/YOUR_COLOR</item>
</style>

<style name="ShapeAppearanceOverlay.App.CustomDialog.Rounded" parent="">
    <item name="cornerFamily">rounded</item>
    <item name="cornerSize">10dp</item>
</style>

then create a Alert Dialog object in Java class like this :

AlertDialog alertDialog =  new MaterialAlertDialogBuilder(this,R.style.MyRounded_MaterialComponents_MaterialAlertDialog)  // for fragment you can use getActivity() instead of this 
                    .setView(R.layout.custom_layout) // custom layout is here 
                    .show();

            final EditText editText = alertDialog.findViewById(R.id.custom_layout_text);   // access to text view of custom layout         
            Button btn = alertDialog.findViewById(R.id.custom_layout_btn);

            btn.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {

                    Log.d(TAG, "onClick: " + editText.getText().toString());
                }
            });

That's all you need to do.

For anyone who like do things in XML, specially in case where you are using Navigation architecture component actions in order to navigate to dialogs

You can use:

<style name="DialogStyle" parent="ThemeOverlay.MaterialComponents.Dialog.Alert">

    <!-- dialog_background is drawable shape with corner radius -->
    <item name="android:background">@drawable/dialog_background</item>

    <item name="android:windowBackground">@android:color/transparent</item>
</style>

You can use the shape for the background as-

<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="@android:color/transparent"/>
<corners android:radius="10dp" />
<padding android:left="10dp" android:right="10dp"/>
</shape>

Have a look on this for the details.

simplest way is to use from

> CardView and its card:cardCornerRadius

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView 
 xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:card="http://schemas.android.com/apk/res-auto"
 android:orientation="vertical"
 android:id="@+id/cardlist_item"
 android:layout_width="match_parent"
 android:layout_height="130dp"
 card:cardCornerRadius="40dp"
 android:layout_marginLeft="8dp"
 android:layout_marginRight="8dp"
 android:layout_marginTop="5dp"
 android:layout_marginBottom="5dp"
 android:background="@color/white">

  <RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="12sp"
    android:orientation="vertical"
    android:weightSum="1">
    </RelativeLayout>

</android.support.v7.widget.CardView>

> And when you are creating your Dialog

dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

Here is the complete solution if you want to control the corner radius of the dialog and preserve elevation shadow

Dialog:

class OptionsDialog: DialogFragment() {

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup, savedInstanceState: Bundle?): View {
    dialog?.window?.setBackgroundDrawable(ColorDrawable(Color.TRANSPARENT))
    return inflater.inflate(R.layout.dialog_options, container)
}

}

dialog_options.xml layout:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="wrap_content"
android:layout_height="wrap_content">

<androidx.cardview.widget.CardView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_margin="40dp"
    app:cardElevation="20dp"
    app:cardCornerRadius="12dp">

    <androidx.constraintlayout.widget.ConstraintLayout
        id="@+id/actual_content_goes_here"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
    </androidx.constraintlayout.widget.ConstraintLayout>

</androidx.cardview.widget.CardView>
</FrameLayout>

The key is to wrap the CardView with another ViewGroup (here FrameLayout) and set margins to create space for the elevation shadow.

For API level >= 28 available attribute android:dialogCornerRadius . To support previous API versions need use

<style name="RoundedDialog" parent="Theme.AppCompat.Light.Dialog.Alert">
        <item name="android:windowBackground">@drawable/dialog_bg</item>
    </style>

where dialog_bg.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item >
        <shape >
            <solid android:color="@android:color/transparent" />
        </shape>
    </item>
    <item
        android:left="16dp"
        android:right="16dp">
        <shape>
            <solid
                android:color="@color/white"/>
            <corners
                android:radius="8dp" />

            <padding
                android:left="16dp"
                android:right="16dp" />
        </shape>
    </item>
</layer-list>

Here is a Basic Solution:

 <style name="Style_Dialog_Rounded_Corner" parent="Theme.AppCompat.Light.Dialog.Alert">
        <item name="android:windowBackground">@drawable/dialog_rounded_corner</item>
        <item name="android:windowMinWidthMinor">85%</item>
    </style>

in Drawable create shape:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="#FFFFFF" />
    <corners android:radius="12dp" />
</shape>

Pass style in Builder Constructor

AlertDialog alert = new AlertDialog.Builder(MainActivity.this,R.style.Style_Dialog_Rounded_Corner).create();

In Kotlin, I am using a class DoubleButtonDialog.Java with line window?.setBackgroundDrawable(ColorDrawable(Color.TRANSPARENT)) as important one

class DoubleButtonDialog(context: Context) : Dialog(context, R.style.DialogTheme) {

    private var cancelableDialog: Boolean = true
    private var titleDialog: String? = null
    private var messageDialog: String? = null
    private var leftButtonDialog: String = "Yes"
    //    private var rightButtonDialog: String? = null
    private var onClickListenerDialog: OnClickListener? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        window?.setBackgroundDrawable(ColorDrawable(Color.TRANSPARENT))
        //requestWindowFeature(android.view.Window.FEATURE_NO_TITLE)
        setCancelable(cancelableDialog)
        setContentView(R.layout.dialog_double_button)
//        val btnNegative = findViewById<Button>(R.id.btnNegative)
//        btnNegative.visibility = View.GONE
//        if (rightButtonDialog != null) {
//            btnNegative.visibility = View.VISIBLE
//            btnNegative.text = rightButtonDialog
//            btnNegative.setOnClickListener {
//                dismiss()
//                onClickListenerDialog?.onClickCancel()
//            }
//        }
        val btnPositive = findViewById<Button>(R.id.btnPositive)
        btnPositive.text = leftButtonDialog
        btnPositive.setOnClickListener {
            onClickListenerDialog?.onClick()
            dismiss()
        }
        (findViewById<TextView>(R.id.title)).text = titleDialog
        (findViewById<TextView>(R.id.message)).text = messageDialog
        super.onCreate(savedInstanceState)
    }

    constructor(
        context: Context, cancelableDialog: Boolean, titleDialog: String?,
        messageDialog: String, leftButtonDialog: String, /*rightButtonDialog: String?,*/
        onClickListenerDialog: OnClickListener
    ) : this(context) {
        this.cancelableDialog = cancelableDialog
        this.titleDialog = titleDialog
        this.messageDialog = messageDialog
        this.leftButtonDialog = leftButtonDialog
//        this.rightButtonDialog = rightButtonDialog
        this.onClickListenerDialog = onClickListenerDialog
    }
}


interface OnClickListener {
    //    fun onClickCancel()
    fun onClick()
}

In layout, we can create a dialog_double_button.xml

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_margin="@dimen/dimen_10"
        android:background="@drawable/bg_double_button"
        android:orientation="vertical"
        android:padding="@dimen/dimen_5">
    
        <TextView
            android:id="@+id/title"
            style="@style/TextViewStyle"
            android:layout_gravity="center_horizontal"
            android:layout_margin="@dimen/dimen_10"
            android:fontFamily="@font/campton_semi_bold"
            android:textColor="@color/red_dark4"
            android:textSize="@dimen/text_size_24"
            tools:text="@string/dial" />
    
        <TextView
            android:id="@+id/message"
            style="@style/TextViewStyle"
            android:layout_gravity="center_horizontal"
            android:layout_margin="@dimen/dimen_10"
            android:gravity="center"
            android:textColor="@color/semi_gray_2"
            tools:text="@string/diling_police_number" />
    
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="@dimen/dimen_10"
            android:gravity="center"
        android:orientation="horizontal"
        android:padding="@dimen/dimen_5">

        <!--<Button
            android:id="@+id/btnNegative"
            style="@style/ButtonStyle"
            android:layout_width="0dp"
            android:layout_height="@dimen/dimen_40"
            android:layout_marginEnd="@dimen/dimen_10"
            android:layout_weight=".4"
            android:text="@string/cancel" />-->

        <Button
            android:id="@+id/btnPositive"
            style="@style/ButtonStyle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:backgroundTint="@color/red_dark4"
            android:fontFamily="@font/campton_semi_bold"
            android:padding="@dimen/dimen_10"
            android:text="@string/proceed"
            android:textAllCaps="false"
            android:textColor="@color/white"
            android:textSize="@dimen/text_size_20" />
    </LinearLayout>
</LinearLayout>

then use drawable.xml as

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid
        android:color="@color/white"/>
    <corners
        android:radius="@dimen/dimen_10" />
    <padding
        android:left="@dimen/dimen_10"
        android:top="@dimen/dimen_10"
        android:right="@dimen/dimen_10"
        android:bottom="@dimen/dimen_10" />
</shape>
 

Create a xml in drawable ,say customd.xml.

then set it at background in your custom Dialog layout xml:

android:background="@drawable/customd"

finally in the java part for custom Dialog class you need to do this:

public class Customdialoque extends DialogFragment {

public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    getDialog().getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

    View view = inflater.inflate(R.layout.activity_customdialoque, container, false);

    return view;
}

I implemented rounded dialog using CardView in the custom layout and setting its corner radius.

Here's my xml code.

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/bottomSheet"
android:layout_width="match_parent"
android:layout_margin="@dimen/padding_5dp"
app:cardCornerRadius="@dimen/dimen_20dp"
android:layout_height="wrap_content">

<androidx.constraintlayout.widget.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/main_gradient_bg"
    android:paddingBottom="32dp">

    <TextView
        android:id="@+id/subdomain_label"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="@dimen/margin_32dp"
        android:layout_marginLeft="@dimen/margin_32dp"
        android:layout_marginTop="@dimen/margin_50dp"
        android:fontFamily="@font/nunito_sans"
        android:text="@string/enter_subdomain"
        android:textColor="@color/white"
        android:textSize="@dimen/size_18sp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent" />


    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="@dimen/dimen_45dp"
        app:layout_constraintLeft_toRightOf="@id/subdomain_label"
        app:layout_constraintTop_toTopOf="parent"
        app:srcCompat="@drawable/ic_baseline_info_24" />

    <EditText
        android:id="@+id/subdomain_edit_text_bottom_sheet"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="@dimen/dimen_20dp"
        android:layout_marginLeft="@dimen/dimen_20dp"
        android:layout_marginEnd="@dimen/dimen_20dp"
        android:layout_marginRight="@dimen/dimen_20dp"
        android:textColor="@color/white"
        android:theme="@style/EditTextTheme"
        app:layout_constraintTop_toBottomOf="@id/subdomain_label" />

    <Button
        android:id="@+id/proceed_btn"
        android:layout_width="@dimen/dimen_150dp"
        android:layout_height="@dimen/margin_50dp"
        android:layout_marginTop="@dimen/margin_30dp"
        android:background="@drawable/primary_btn_bg"
        android:text="@string/proceed"
        android:textAllCaps="false"
        android:textColor="@color/white"
        android:textSize="@dimen/size_18sp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/subdomain_edit_text_bottom_sheet" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>

After that, i called it in Kotlin as follows :-

    val builder = AlertDialog.Builder(mContext)
    val viewGroup: ViewGroup = findViewById(android.R.id.content)
    val dialogView: View = 
    LayoutInflater.from(mContext).inflate(R.layout.subdomain_bottom_sheet, 
    viewGroup, false)
    val alertDialog: AlertDialog = builder.create()
    alertDialog.setView(dialogView,0,0,0,0)
    alertDialog.show()
    val windowParam = WindowManager.LayoutParams()
    windowParam.copyFrom(alertDialog.window!!.attributes)
    windowParam.width = AppConstant.getDisplayMetricsWidth(mContext) - 100
    windowParam.height = WindowManager.LayoutParams.WRAP_CONTENT
    windowParam.gravity = Gravity.CENTER
    alertDialog.window!!.attributes = windowParam
    
   
    alertDialog.window!!.setBackgroundDrawable
    (ColorDrawable(Color.TRANSPARENT))

Where last line is very important. Missing that would cause a color(mostly white) to show behind the corners.