Android bottom sheet layout

Android: Bottom sheet

Bottom sheet is a component that slides up from bottom of the screen to reveal more content. You can find more detailed information of Bottom Sheet on Google Material Design guidelines.

Adding resources

Add the latest appcompat and design support library to your project.

Make your activity extend AppCompatActivity.

Creating layouts

Bottom sheet content

We’ll include the layouts for the sake of simplicity. This is the layout that will contain the content of the bottom sheet. File is bottom_sheet.xml.

behavior_peekHeight: Defines the height of the visible part.

behavior_hideable: Defines if the bottom sheet can be hidden by swiping it down.

Add the CoordinatorLayout as the root view. Then include the bottom sheet view as the direct child of the CoordinatorLayout. The layouts app_bar and activity_bottom_sheet_content are some view references that are not related to the bottom sheet. So you can replace or remove them.

At this point the bottom sheet dialog should work like this.

Dynamic control

Behaviors and attributes of the bottom sheet dialog can be controlled dynamically in Java as well.

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Hands-on with Material Components for Android: Bottom Sheets

Part 3 of a series covering practical usage of Material Components for Android

This post will be covering the features and API of Bottom Sheet components. To find out how to handle initial setup of Material Components for Android (including the Gradle dependency and creating an app theme), please see my original post:

Setting up a Material Components theme for Android

Attribute by attribute

Bottom Sheets are surface components that hold supplementary screen content. They are anchored to the bottom of a screen (making them ergonomic on mobile/tablet devices) and, similar to Dialogs, are elevated over main screen content. In most cases, they can be expanded/dismissed via a drag up/down gesture.

From a design perspective, there are two types of Bottom Sheets:

• Standard Bottom Sheet: They operate independently to (and allow for simultaneous interaction with) primary screen content. They can be in an expanded, collapsed or hidden state.
• Modal Bottom Sheet: They block primary screen content and must be interacted with or dismissed. A semi-transparent scrim, which can be tapped to dismiss, is displayed behind them to indicate the underlying UI is temporarily inaccessible.

Note: A third type exists: Expanding Bottom Sheet . At the time of writing, the latest release of Material Components for Android is 1.2.0-alpha06 and there is no standard component or class to handle this. A custom implementation could be achieved with something like MotionLayout , but that is outside the scope of this article and won’t be covered.

Basic usage 🏁

Implementing Bottom Sheets is not as simple as using a single component. There exists different classes within Material Components for Android for each type of sheet.

Standard Bottom Sheet

A child View of a CoordinatorLayout can have Standard Bottom Sheet characteristics enabled by using BottomSheetBehavior . In doing so, the bottom anchoring, drag up/down gesture support and animated state transitions and more are handled for us.

This can be done in your screen layout like so:

In the above example, our Bottom Sheet is in fact the FrameLayout . The most important part is that the layout_behavior attribute is set to com.google.android.material.bottomsheet.BottomSheetBehavior . We have also applied some default styling (background shape/tint, elevation, etc.) with the bottomSheetStyle attribute, which will be discussed in more detail below in the “Theming” section.

Modal Bottom Sheet

For Modal Bottom Sheets, the implementation is different. The BottomSheetDialogFragment class (which extends AppCompatDialogFragment ) provides the desired modal behavior in addition to existing DialogFragment functionality.

First of all, a subclass of BottomSheetDialogFragment needs to be created and the onViewCreated callback must be overridden to provide a layout for the contents of the sheet:

Then, inside an AppCompatActivity , the class can be used to show the sheet like so:

It is worth noting that, under the hood, BottomSheetDialogFragment also makes use of BottomSheetBehavior in a BottomSheetDialog class to convert a standard AppCompatDialogFragment to one that has Bottom Sheet characteristics. BottomSheetDialog can be used independently if you don’t want to use a Fragment .

Adjusting behavior ⚙️

There exists a variety of attributes that can be used to adjust the behavior of both Standard and Modal Bottom Sheets. This includes things like “peek” (collapsed) height, hidability, content fitting and more.

Applying attributes

For Standard Bottom Sheets, applying these attributes can be done in XML by applying the attributes to the same child View that has the layout_behavior attribute set to BottomSheetBehavior . In our example above in the “Basic usage” section, this is the FrameLayout .

Alternatively, it can be done programmatically:

For Modal Bottom Sheets there is no XML layout definition for the sheet itself, but we can make use of app-level theme attributes and styles:

Alternatively, it can be done programmatically:

The attributes

Now that we know how to apply attributes, let’s dive into what attributes are available to us.

• behavior_hideable : Determines whether or not the sheet can be hidden when using a drag down gesture (bearing in mind that it can always be hidden programmatically). The default value is false for Standard Bottom Sheets and true for Modal Bottom Sheets.
• behavior_draggable : Determines whether or not the sheet can be collapsed/expanded when using a drag gesture (bearing in mind that a custom way to expand/collapse the sheet will need to be implemented). The default value is true.
• behavior_skipCollapsed : Determines whether or not the collapsed state should be ignored when hiding the sheet. This has no effect if behavior_hideable is not set to true. The default value is false.
• behavior_fitToContents : Determines whether or not the height of the expanded sheet wraps its contents. Alternatively, it expands in two stages: half the height of the parent container, full height of the parent container. The default value is true.
• behavior_halfExpandedRatio : Determines the height of the sheet (as a ratio of the parent container height) when in half-expanded state. This has no effect if behavior_fitToContents is not set to false and should be greater than the peek height. The default value is 0.5 (the recommended ratio in the Material Guidelines).
• behavior_expandedOffset : Determines the offset of the sheet from the top of the parent container when in expanded state. This has no effect if behavior_fitToContents is not set to false and should be greater than the offset when in half-expanded state. The default value is 0dp (the top of the sheet matches the top of the parent container).
• behavior_peekHeight : The initial “peek” (collapsed state) height of the sheet. The default value is auto , which sets the peek height at the 16:9 ratio keyline of the parent container. A dimension (or pixel value, programmatically) can otherwise be used.

A word on modal dismiss animations

You might notice that, for modal bottom sheets (i.e. BottomSheetDialog or BottomSheetDialogFragment ), the animation used when calling dismiss() does not match the normal drag-to-dismiss animation. As of Material Components for Android 1.1.0-alpha10 , there exists an opt-in flag to align these animations:

Setting (and saving) state 💾

The state of a Bottom Sheet can be changed via user interaction, but we can also do so programmatically. By default, these state changes are animated.

Setting state

The following states can be set on a BottomSheetBehavior :

• STATE_EXPANDED : The sheet is fully expanded.
• STATE_COLLAPSED : The sheet is collapsed (“peeking”).
• STATE_HIDDEN : The sheet is hidden and can only be re-shown programmatically.
• STATE_HALF_EXPANDED : The sheet is half-expanded (only applicable if behavior_fitToContents has been set to false).

This can be done like so:

While these should not be set programmatically, a BottomSheetBehavior can also be in one of the following states:

• STATE_DRAGGING : The sheet is being dragged up/down via a gesture.
• STATE_SETTLING : The sheet is animating up/down as a result of programmatically setting its state.

Retaining attribute state on configuration change

We can choose which aspects of state we wish to preserve when the host Activity experiences a configuration change (i.e. the View representing our Bottom Sheet is destroyed and recreated). In this case, “state” refers to the attributes discussed in the “Adjusting behavior” section above.

The following flags can be set (or combined with bitwise OR operations) on a BottomSheetBehavior :

• SAVE_PEEK_HEIGHT : The behavior_peekHeight attribute will be preserved.
• SAVE_FIT_TO_CONTENTS : The behavior_fitToContents attribute will be preserved.
• SAVE_HIDEABLE : The behavior_hideable attribute will be preserved.
• SAVE_SKIP_COLLAPSED : The behavior_skipCollapsed attribute will be preserved.
• SAVE_ALL : All aforementioned attributes will be preserved.
• SAVE_NONE : No attributes will be preserved. This is the default value.

This can be done like so:

There is also a corresponding behavior_saveFlags XML attribute which can be used in layouts and styles.

Listening for state change and slide callbacks 👂

We can listen for changes to Bottom Sheet state as well as the current slide offset. This can be used to coordinate other UI changes, such as fading in/out other View s, adjusting system bar color, etc.

A BottomSheetCallback can be added to a BottomSheetBehavior like so:

In the onStateChanged callback, the newState parameter will be one of the state constants discussed above in the “Setting (and saving) state” section.

In the onSlide callback, the slideOffset parameter is a Float value in the [-1.0, 1.0] range. Hidden state is -1.0, collapsed state is 0.0 and expanded state is 1.0. The value interpolates linearly and increases as the sheet moves upwards.

Note: Multiple callbacks can be added (and removed via BottomSheetBehavior#removeBottomSheetCallback ).

Theming 🎨

Bottom Sheets can be themed in terms of the three Material Theming subsystems: color, typography and shape. For Standard Bottom Sheets, there are no existing style variants but we can create our own. When implementing a global Standard Bottom Sheet style, reference it in your app theme with the bottomSheetStyle attribute. For Modal Bottom Sheets, we have already shown which styles/attributes to use in the “Adjusting behavior” section above. Theming attributes are applicable to both sheet types.

Color

The color of a Bottom Sheet background can be customized with the backgroundTint attribute. This defaults to colorSurface .

Typography

There is no primary text as part of Bottom Sheet components. Text included in the contents of a Bottom Sheet will be styled according to the class/component used as well as the fontFamily app theme attribute.

Shape

The shape of a Bottom Sheet background can be customized with the shapeAppearance attribute. This defaults to shapeAppearanceLargeComponent .

More resources 📚

• The source code for the Playground app used in this article can be found on GitHub.
• Bottom Sheets Design Documentation
• Bottom Sheet API Documentation
• Modal Bottom Sheet API Documentation

I hope this post has provided some insight into Bottom Sheets and how they can be used in your Android app(s). If you have any questions, thoughts or suggestions then I’d love to hear from you!

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Android Bottom Sheet / Bottom Sheet Behavior

Jan 2, 2019 · 4 min read

Android Bottom Sheet is a component that slides up from the bottom of the screen having multiple options. Here are the examples of the Bottom sheet from apps.

There are two types of bottom sheets, Persistent Bottom Sheet and Modal Bottom Sheet.

Persistent Bottom Sheet: This bottom sheet shows in-application content. It will be shown at the base of the screen with a portion of its part noticeable (we can characterize measurements in dp), it shows full substance in the wake of growing it. It has a littler height.

Modal Bottom Sheet: This botom sheet functions as a menu or discourse with choices, it implies this replaces menu or exchange. It has a higher height than the determined base sheet. For the most part, they are utilized for incorporating profound connecting picker activities.

Let’s start to implement the first persistent bottom sheet.

After creating a new project, open build.gradle file in app level, add support design dependency because the bottom sheet is the component of the android design support library.

Create bottom_sheet.xml layout:

Create conent_main.xml layout, that displays on-screen without the bottom sheet.

Now crea t e activity_main.xml including content and bottom sheet layout.

Now code in MainActivity.java

Now lets a look at Modal bottom sheet, the easiest way for the bottom sheet. Modal bottom sheet will be shown as an external dialog using BottomSheetDialog or BottomSheetDialogFragment.

As component we are using (BottomSheetDialog or BottomSheetDialogFragment)is a dialog itself. So its behavior is same as normal dialog, that you can touch outside to dismiss bottom sheet using this method.

We will show the bottom sheet dialog with the same UI that we used before.

That’s it. Now you have learnt the implementation of the bottom sheet. Find code her

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