BottomSheetDialog is a dialog that slides up from the bottom of the screen, partially overlaying the main content. It is commonly used for choices, menus, or actions that don't require a full-screen transition.

1. Creating a BottomSheetDialog

To instantiate a BottomSheetDialog, provide a context and a optional theme style. The style should set the dialog background to transparent so that a custom shape drawable can be applied.

BottomSheetDialog sheetDialog = new BottomSheetDialog(this, R.style.BottomSheetDialog);

View contentView = LayoutInflater.from(this).inflate(R.layout.dialog_bottom_sheet, null);
sheetDialog.setContentView(contentView);

// Optionally prevent dismissal on outside touch
// sheetDialog.setCanceledOnTouchOutside(false);

sheetDialog.show();

2. Layout Definition

Define the layout resource dialog_bottom_sheet.xml that will be inflated and set as the dialog content. The root container uses a custom background drawable for rounded corners.

<?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/shape_bottom_sheet_rounded"
    android:orientation="vertical">

    <TextView
        android:id="@+id/action_gallery"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"
        android:text="Choose from Gallery"
        android:textColor="#191919"
        android:textSize="15sp" />

    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="#F5F5F5" />

    <TextView
        android:id="@+id/action_previous"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"
        android:text="View Previous Avatar"
        android:textColor="#191919"
        android:textSize="15sp" />

    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="#F5F5F5" />

    <TextView
        android:id="@+id/action_save"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"
        android:text="Save to Device"
        android:textColor="#191919"
        android:textSize="15sp" />

    <View
        android:layout_width="match_parent"
        android:layout_height="10dp"
        android:background="#F5F5F5" />

    <TextView
        android:id="@+id/action_cancel"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"
        android:text="Cancel"
        android:textColor="#191919"
        android:textSize="15sp" />

</LinearLayout>

3. Displaying the Dialog

Call sheetDialog.show() to present the bottom sheet. The dialog will animate from the bottom edge and overlay the current activity.

4. Adding Rounded Corners

Create a drawable resource shape_bottom_sheet_rounded.xml in the res/drawable directory. This shape applies rounded corners only to the top-left and top-right edges.

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

    <corners
        android:topLeftRadius="10dp"
        android:topRightRadius="10dp" />
    <solid android:color="@android:color/white" />

</shape>

To make the corners visible, the dialog's parent background must be transparent. Define the following styles in you're themes.xml (under res/values):

<style name="BottomSheetDialog" parent="Theme.Design.Light.BottomSheetDialog">
    <item name="bottomSheetStyle">@style/bottomSheetStyleWrapper</item>
</style>

<style name="bottomSheetStyleWrapper" parent="Widget.Design.BottomSheet.Modal">
    <item name="android:background">@android:color/transparent</item>
</style>

Then pass R.style.BottomSheetDialog as the second argument when constructing the BottomSheetDialog:

BottomSheetDialog sheetDialog = new BottomSheetDialog(this, R.style.BottomSheetDialog);