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Android Studio

[TOC]

Usage

Make sure you have followed android build instructions already.

build/android/gradle/generate_gradle.py --output-directory out/Debug

The above commands create a project dir gradle under your output directory. Use --project-dir <project-dir> to change this.

To import the project:

  • Use "Import Project", and select the directory containing the generated project, e.g. out/Debug/gradle.

See android_test_instructions.md for more information about building and running emulators.

Feel free to accept Android Studio's recommended actions. generate_gradle.py should have already set up a working version of the gradle wrapper and the android gradle plugin, as well as a default Android SDK location at ~/Android/Sdk. Since the same script needs to support various versions of Android Studio, the defaults may have lower version than the one recommended by your version of Android Studio. After you accept Android Studio's update actions the generate_gradle.py script will try to keep the newer versions when it is re-run.

You'll need to re-run generate_gradle.py whenever new directories containing source files are added.

  • After regenerating, Android Studio should prompt you to "Sync". If it doesn't, try some of the following options:
    • File -> "Sync Project with Gradle Files"
    • Button with two arrows on the right side of the top strip.
    • Help -> Find Action -> "Sync Project with Gradle Files"
    • After gn clean you may need to restart Android Studio.
    • File -> "Invalidate Caches / Restart..."

How It Works

By default, only an _all module containing all java apk targets is generated. If just one apk target is explicitly specified, then a single apk module is generated.

If you really prefer a more detailed structure of gn targets, the deprecated --split-projects flag can be used. This will generate one module for every gn target in the dependency graph. This can be very slow and is no longer supported.

Generated files

Most generated .java files in GN are stored as .srcjars. Android Studio does not support them. Our build will automatically extract them to a generated_java directory in the output directory during the build. Thus if a generated file is missing in Android Studio, build it with ninja first and it should show up in Android Studio afterwards.

Native Files

This option is deprecated and no longer supported since Android Studio is very slow when editing in a code base with a large number of C++ files, and Chromium has a lot of C++ code. It is recommended to use VS Code to edit native files and stick to just editing java files in Android Studio.

If you still want to enable editing native C/C++ files with Android Studio, pass in any number of --native-target [target name] flags in order to use it. The target must be the full path and name of a valid gn target (no short-forms). This will require you to install cmake and ndk when prompted. Accept Android Studio's prompts for these SDK packages.

You need to disable a new gradle option in order to edit native files: File -> Settings -> Experimental -> Gradle and uncheck "Only resolve selected variants".

This is not necessary, but to avoid "This file is not part of the project...", you can either add an extra --native-target flag or simply copy and paste the absolute path to that file into the CMakeLists.txt file alongside the existing file paths. Note that changes to CMakeLists.txt will be overwritten on your next invocation of generate_gradle.py.

Example:

build/android/gradle/generate_gradle.py --native-target //chrome/android:libchrome

Tips

  • Use environment variables to avoid having to specify --output-directory.
    • Example: Append export CHROMIUM_OUT_DIR=out; export BUILDTYPE=Debug to your ~/.bashrc to always default to out/Debug.
  • Using the Java debugger is documented here.
  • Configuration instructions can be found here. One suggestions:
    • Launch it with more RAM: STUDIO_VM_OPTIONS=-Xmx2048m /opt/android-studio-stable/bin/studio-launcher.sh
  • If you ever need to reset it: rm -r ~/.config/Google/AndroidStudio*/
  • Import Chromium-specific style and inspections settings:
    • Help -> Find Action -> "Code Style" (settings) -> Java -> Scheme -> Import Scheme
      • Select tools/android/android_studio/ChromiumStyle.xml -> OK
    • Help -> Find Action -> "Inspections" (settings) -> Profile -> Import profile
      • Select tools/android/android_studio/ChromiumInspections.xml -> OK
  • Turn on automatic import:
    • Help -> Find Action -> "Auto Import"
      • Tick all the boxes under "Java" and change the dropdown to "All".
  • Turn on documentation on mouse hover:
    • Help -> Find Action -> "Show quick documentation on mouse move"
  • Turn on line numbers:
    • Help -> Find Action -> "Show line numbers"
  • Turn off indent notification:
    • Help -> Find Action -> "Show notifications about detected indents"
  • Format changed files (Useful for changes made by running code inspection):
    • Set up version control
      • File -> Settings -> Version Control
      • Add src directories
    • Commit changes and reformat
      • Help -> Find Action -> "Commit Changes"
      • Check "Reformat code" & "Optimize imports" and commit
  • Change theme from GTK+ to another one to avoid invisible menus.
    • Help -> Find Action -> "Theme: Settings > Appearance"

Useful Shortcuts

  • Shift - Shift: Search to open file or perform IDE action
  • Ctrl + N: Jump to class
  • Ctrl + Shift + T: Jump to test
  • Ctrl + Shift + N: Jump to file
  • Ctrl + F12: Jump to method
  • Ctrl + G: Jump to line
  • Shift + F6: Rename variable
  • Ctrl + Alt + O: Organize imports
  • Alt + Enter: Quick Fix (use on underlined errors)
  • F2: Find next error

Building with Gradle

Gradle builds are not supported. Only editing is supported in Android Studio. Use ninja to build as usual.

Status

What works

  • Android Studio v2021~v2023.
  • Java editing.
    • Application code in main sourceset.
    • Instrumentation test code in androidTest sourceset.
  • Native code editing (deprecated, use VS Code instead).
  • Symlinks to existing .so files in jniLibs (doesn't generate them).
  • Editing resource xml files
  • Layout editor (limited functionality).
  • Java debugging (see here).
  • Import resolution and refactoring across java files.
  • Separate Android SDK for Android Studio.

What doesn't work

  • Building with Gradle.
  • The "Make Project" button doesn't work.
    • Stick to using autoninja to build targets and just use Android Studio for editing java source files.
  • No active work is underway or planned to expand Android Studio support.