Android Studio 3.1 (March 2018)

Android Studio 3.1.0 is a major release that includes a variety of new features and improvements.

Coding/IDE

IntelliJ 2017.3.3

The core Android Studio IDE has been updated with improvements from IntelliJ IDEA through the 2017.3.3 release. Improvements include better control flow analysis for collections and strings, improved nullability inference, new quick fixes, and much more.

For details, see the JetBrains release notes for IntelliJ IDEA versions 2017.2 and 2017.3, as well as the JetBrains release notes for bug-fix updates.

SQL editing improvements with Room

When you use the Room database library, you can take advantage of several improvements to SQL editing:

• Code completion within a Query understands SQL tables (entities), columns, query parameters, aliases, joins, subqueries, and WITH clauses.
• SQL syntax highlighting now works.
• You can right-click a table name in SQL and rename it, which also rewrites the corresponding Java or Kotlin code (including, for example, the return type of the query). Renaming works in the other direction, too, so renaming a Java class or field rewrites the corresponding SQL code.
• SQL usages are shown when using Find usages (right-click and choose Find usages from the context menu).
• To navigate to an SQL entity's declaration in Java or Kotlin code, you can hold Control (Command on Mac) while clicking the entity.

For information on using SQL with Room, see Save data in a local database using Room.

Updates to data binding

This update includes several improvements for data binding:

• You can now use a LiveData object as an observable field in data binding expressions. The ViewDataBinding class now includes a new setLifecycle() method that you use to observe LiveData objects.

• The ObservableField class can now accept other Observable objects in its constructor.

• You can preview a new incremental compiler for your data binding classes. For details of this new compiler and instructions for enabling it, see Data Binding Compiler V2.

  Benefits of the new compiler include the following:

  • ViewBinding classes are generated by the Android Plugin for Gradle before the Java compiler.
  • Libraries keep their generated binding classes when the app is compiled, rather than being regenerated each time. This can greatly improve performance for multi-module projects.

Compiler and Gradle

D8 is the default DEX compiler

The D8 compiler is now used by default for generating DEX bytecode.

This new DEX compiler brings with it several benefits, including the following:

• Faster dexing
• Lower memory usage
• Improved code generation (better register allocation, smarter string tables)
• Better debugging experience when stepping through code

You don't need to make any changes to your code or your development workflow to get these benefits, unless you had previously manually disabled the D8 compiler.

If you set android.enableD8 to false in your gradle.properties, either delete that flag or set it to true:

        android.enableD8=true
      

For details, see New DEX compiler.

Incremental desugaring

For projects that use Java 8 language features, incremental desugaring is enabled by default, which can improve build times.

Desugaring converts syntactic sugar into a form that the compiler can process more efficiently.

You can disable incremental desugaring by specifying the following in your project's gradle.properties file:

        android.enableIncrementalDesugaring=false
      

Simplified output window

The Gradle Console has been replaced with the Build window, which has Sync and Build tabs.

For details about how to use the new, simplified Build window, seeMonitor the build process.

Batch updates and indexing concurrency

The Gradle sync and IDE indexing processes are now much more efficient, reducing time wasted on many redundant indexing operations.

C++ and LLDB

We have made many quality and performance improvements in the coding, syncing, building, and debugging phases of C++ development. Improvements include the following:

• If you work with large C++ projects, you should notice a significant improvement in the reduction of time spent building symbols. Sync time is also greatly reduced for large projects.

• Performance when building and syncing with CMake has been improved through more aggressive reuse of cached results.

• The addition of formatters ("pretty printers") for more C++ data structures makes LLDB output easier to read.

• LLDB now works with only Android 4.1 (API level 16) and higher.

Note: Native debugging with Android Studio 3.0 or greater does not work on 32-bit Windows. If you are using 32-bit Windows and need to debug native code, use Android Studio 2.3.

Kotlin

Kotlin upgraded to version 1.2.30

Android Studio 3.1 includes Kotlin version 1.2.30.

Kotlin code now analyzed with command-line lint check

Running lint from the command line now analyzes your Kotlin classes.

For each project that you would like to run lint on, Google's Maven repository must be included in the top-level build.gradle file. The Maven repository is already included for projects created in Android Studio 3.0 and higher.

Performance tools

Sample native C++ processes with CPU Profiler

The CPU Profiler now includes a default configuration to record sampled traces of your app's native threads. You can use this configuration by deploying your app to a device running Android 8.0 (API level 26) or higher and then selecting Sampled (Native) from the CPU Profiler's recording configurations dropdown menu. After that, record and inspect a trace as you normally would.

You can change default settings, such as the sampling interval, by creating a recording configuration.

To switch back to tracing your Java threads, select either a Sampled (Java) or Instrumented (Java) configuration.

Filter CPU traces, memory allocation results, and heap dumps

The CPU Profiler and Memory Profiler include a search feature that allows you to filter results from recording a method trace, memory allocations, or heap dump.

To search, click Filter in the top-right corner of the pane, type your query, and press Enter.

Tip: You can also open the search field by pressing Control + F (Command + F on Mac).

In the CPU Profiler's Flame Chart tab, call stacks that include methods related to your search query are highlighted and moved to the left side of the chart.

For more information on filtering by method, class, or package name, see Record and inspect method traces.

Request tab in the Network Profiler

The Network Profiler now includes a Request tab that provides details about network requests during the selected timeline. In previous versions, the Network Profiler only provided information about network responses.

Thread View in the Network Profiler

After selecting a portion of the timeline in the Network Profiler, you can select one of the following tabs to see more detail about the network activity during that timeframe:

• Connection View: Provides the same information as previous versions of Android Studio—it lists files that were sent or received during the selected portion of the timeline across all of your app's CPU threads. For each request, you can inspect the size, type, status, and transmission duration.
• Thread View: Displays network activity of each of your app's CPU threads. This view allows you to inspect which of your app's threads are responsible for each network request.

Layout Inspector

The Layout Inspector gained new features, including some functionality previously provided by the deprecated Hierarchy Viewer and Pixel Perfect tools:

• Zoom buttons and keyboard shortcuts for navigating and inspecting layouts
• Reference grid overlay
• Ability to load a reference image and use it as an overlay (useful for comparing your layout with a UI mockup)
• Render subtree preview to isolate a view in a complex layout

Layout Editor

The Palette in the Layout Editor has received many improvements:

• Reorganization of categories for views and layouts.
• New Common category for views and layouts, which you can add to with a Favorite command.
• Improved search for views and layouts.
• New commands for opening documentation for a specific view or layout element.

You can use the new Convert view command in the Component tree or design editor to convert a view or layout to another type of view or layout.

You can now easily create constraints to items near the selected view using the new Create a connection buttons in the view inspector at the top of the Attributes window.

Run and Instant Run

The behavior of the Use same selection for future launches option in the Select deployment target dialog has been made more consistent. If the Use same selection option is enabled, then the Select deployment target dialog opens only the first time that you use the Run command until the selected device is no longer connected.

When targeting a device running Android 8.0 (API level 26) or higher, Instant Run can deploy changes to resources without causing an application restart. This is possible because the resources are contained in a split APK.

Emulator

For details of what's new and changed in the emulator since Android Studio 3.0, see the Android Emulator release notes from version 27.0.2 through version 27.1.12.

Major improvements include the following:

• Quick Boot snapshots for saving of emulator state and faster start, with the ability to use the Save now command to save a custom start state.
• Windowless emulator screen.
• System images for Android 8.0 (API level 26), Android 8.1 (API level 27), and Android P Developer Preview.

User interface and user experience improvements

More tooltips, keyboard shortcuts, and helpful messages

We have added tooltips and helpful message overlays in many places throughout Android Studio.

To see keyboard shortcuts for many commands, just hold the mouse pointer over a button until the tooltip appears.

Tools > Android menu removed

The Tools > Android menu has been removed. Commands that were previously under this menu have been moved.

• Many commands moved to directly under the Tools menu.
• The Sync project with gradle files command moved to the File menu.
• The Device Monitor command has been removed, as described below.

Device Monitor available from the command line

In Android Studio 3.1, the Device Monitor serves less of a role than it previously did. In many cases, the functionality available through the Device Monitor is now provided by new and improved tools.

See the Device Monitor documentation for instructions for invoking the Device Monitor from the command line and for details of the tools available through the Device Monitor.