Introduction to Android Jetpack

Download Manager

The DownloadManager service helps you download files in the background. Avoid dealing with connection problems, retrying and even system reboots by using the DownloadManager service. Since the DownloadManager is a system service, you can just start a download and listen for a broadcast event to handle the finished download. No need to worry about network issues or crashes.

You can find more information here: Download Manager.

Slices

The Slices library is new and lets you create UI templates to share your data through the system in rich, flexible layouts. One of the examples Google gave at Google I/O was a weather app that can show more data depending on the space it has to show. Currently, it is only used by the Google Search App but should extend to the Google Assistant.

You can make your app data available to these apps using Slices so that a user can find information from your app by using Google Search or the Assistant.

You can find more information here: Slices

Jetpack: UI

Most of the UI libraries in Jetpack are based on existing code. They include: animations, fragments, palettes, layouts, Emojis, Android Auto, Wear and TV. The EmojiCompat library is the newest of the libraries and gives you up-to-date emojis and the fonts needed to use them.

You can find more information about the UI area here: UI.

Animation

This part of Jetpack includes APIs for the different types of animations available on Android. The Jetpack site documentation covers the old as well as new ways to use animations. Vector graphics and vector animations are included as well.

There is also a physics-based animation system that includes spring and fling animations. You can setup transitions between activities as well as property and object animations. You can also set a layout to animate any updates you make to the layout.

You can find more information here: Animations.

Emoji

EmojiCompat handles emoji characters and uses downloadable font support. This allows your app to stay up to date with the latest emojis without depending on the Android OS. Whenever you update this library dependency, you will have the latest emojis. There is a concrete Span class called EmojiSpan that is used to create emojis in your text.

You can find more information here: Emoji.

Fragment

The Fragment support class has moved into this part of Jetpack. It includes the different kinds of fragments, such as: DialogFragment, ListFragment, and PreferenceFragmentCompat. An important part of a Fragment is the lifecycle, and the Fragment class included in Jetpack is well-integrated with the Lifecycle class in Jetpack: Architecture.

You can find more information here: Fragments.

Layout

A Layout defines the Views and ViewGroups in your app. In the Jetpack Layout documentation, you learn how to declare layouts in XML and in code. It also describes some of the more common layouts, such as LinearLayout, RelativeLayout and the newer ConstraintLayout. Moreover, you’ll pick up tips on more specific features like creating lists of items with RecyclerView, as well as the card layout CardView.

You can find more information here: Layouts.

Palette

The Palette library allows you to pick colors for themes and from images to make your UI’s match your images. You can also create a palette and choose different colors using the Palette.Builder class. Some of the types of colors produced are: Light Vibrant, Vibrant, Dark Vibrant, Light Muted, Muted and Dark Muted.

You can find more information here: Palettes.

TV

If you are building your app for Android TV, then the TV part of Jetpack is for you. You can control TV Hardware and controllers and create a navigation system that works for TVs. There is the leanback theme that is used for TV layouts and the Leanback library helps with TV controls. You can setup a D-pad controller to let users navigate the TV UI.

You can find more information here: TV.

Wear

Wear OS is the version of Android for wearable devices. You can create an app that plays media, controls your media from a watch, or create a standalone watch app or watch face.

You can find more information here: Wear.

Auto

Jetpack helps you develop apps for Android Auto — audible only, messaging, working with hardware and more. You can provide audio playback for the car as well as messaging. You can test Auto apps on the car screen using the Desktop Head Unit (DHU), which is a testing tool that allows you to test without the hardware.

You can find more information here: Auto.

Where to Go From Here?

As you can see, there is quite a lot included in Google’s new Android Jetpack package. All of the libraries you know and love can be found there, as well as several new ones.

In this article, you were introduced to the four main parts of Jetpack: Architecture, Foundation, UI and Behavior. Some of the new libraries, like the Navigation library, will change the way you write your apps, making it easier than ever. WorkManager solves a long standing problem of reliably running jobs at different times on different OS versions. Paging will help with larger data sets and let you use RecyclerViews and adapters with less code. The Android KTX library makes working in Kotlin even easier and will continue to evolve. Slices are new and, as you learn more, you should be able to make available more of your data outside of your app. With the Emoji library, you can have all of the latest and best emojis available.

Hopefully this post provided a good overview of what is available in Jetpack and will get you excited about using something new. The main Jetpack page is located here: Android Jetpack

If you would like more in-depth information on Jetpack Navigation, you can find a screencast here. We also have screencasts on LiveData, ViewModel, and Paging Library. Finally, you can find a short introduction to WorkManager in our Background Processing course here.

Let us know what part of Android Jetpack you are most looking forward to using in the discussion forum below!