Tools for building Android applications with Mirah
Ruby Mirah
Switch branches/tags
Nothing to show
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Failed to load latest commit information.


A tool for writing Android applications in Mirah.

Pindah logo


You must have the Android SDK installed with the tools/ directory placed on your $PATH.

Inside your tools/ directory, the android program will allow you to download "platform" packages corresponding with the Android versions you wish to develop against. You'll need to install "Android SDK Platform Tools" and at least one platform revision to get started. At the time of this writing, Android 2.3.3 (revision 10) and above covers 100% of the market and is a reasonable target for new applications.

Once the platform tools are installed, place the SDK's platform-tools/ directory on your $PATH.

You will also need the following tools installed before you can develop with Pindah:

JRuby/Mirah compatability

Pindah has been successfully tested with the following JRuby and Mirah combinations:

JRuby/Mirah 0.1.0 0.1.1 0.1.2
1.7.3 x x

Ruby version management

While Linux users can obtain OpenJDK from their distribution, it is recommended that all users utilize something like rbenv, rvm, or uru to manage their Ruby installations and gems:

# rbenv

$ rbenv install jruby-1.7.4
$ rbenv --global jruby-1.7.4
$ gem install rake mirah

# rvm

$ rvm install jruby-1.7.4
$ gem install rake mirah


To install the latest stable version of Pindah, simply install the gem from the command line:

gem install pindah

If you want to play with the latest development version, clone the repo onto your local machine:

$ git clone git://
$ cd pindah/
$ gem build pindah.gemspec
$ gem install


Similar to other Ruby projects like Rails or Ruboto, the pindah executable is responsible for creating and configuring your new Android project(s). To get started with a simple project, call the pindah command like so:

pindah create org.example.hello_world

This will create an empty skeleton project with the package name org.example.hello_world in the current directory.

You can also configure your project with the following options:

  • To create your project in a specific location, specify an optional path for your new project: pindah create org.example.hello_world path_to_project

  • To create and configure a basic initial activity for your project, specify an activity name after the path: pindah create org.example.hello_world path_to_project StartActivity

All other project management tasks are handled by rake. For a summary of all possible tasks you can run on your new project, run rake -T from your project directory:

$ rake -T

rake clean             # Removes output files created by other targets.
rake compile           # Run compile
rake debug             # Builds the application and signs it with a debug key.
rake install           # Installs the newly build package.
rake installd          # Installs (only) the debug package.
rake installi          # Installs (only) the instrumented package.
rake installr          # Installs (only) the release package.
rake installt          # Installs (only) the test and tested packages.
rake instrument        # Builds an instrumented packaged.
rake javac             # Compiles and other gen/ files.
rake logcat            # Tail logs from a device or a device or emulator
rake release           # Builds the application in release mode.
rake release_unsigned  # Builds the application in release mode.
rake spec              # Print the project spec
rake test              # Runs tests from the package defined in test.package property
rake uninstall         # Uninstalls the application from a running emulator or device.

Directory structure

Pindah follows the default Android directory structure when creating new projects:

$ pindah create org.example.hello_world hello_world/ StartActivity

Created 'hello_world/src/org/example/hello_world'.
Created 'hello_world/bin'.
Created 'hello_world/libs'.
Created 'hello_world/res'.
Created 'hello_world/res/drawable-hdpi'.
Created 'hello_world/res/drawable-ldpi'.
Created 'hello_world/res/drawable-mdpi'.
Created 'hello_world/res/layout'.
Created 'hello_world/res/values'.
Created project in hello_world.

$ cd hello_world && tree
|-- AndroidManifest.xml
|-- libs
|-- Rakefile
|-- res
|   |-- drawable-hdpi
|   |   `-- ic_launcher.png
|   |-- drawable-ldpi
|   |   `-- ic_launcher.png
|   |-- drawable-mdpi
|   |   `-- ic_launcher.png
|   |-- layout
|   |   `-- main.xml
|   `-- values
|       `-- strings.xml
`-- src
    `-- org
        `-- example
            `-- hello_world
                `-- StartActivity.mirah

12 directories, 8 files

Here are a few quick notes about the directory structure pictured above:

  • The AndroidManifest.xml file describes the contents and metadata of your application.
  • The res/ directory contains application resources like icons, layout descriptions, and strings.
  • The src directory contains the Java and Mirah source code for your project.

Other Android-specific directories may be created and used outside of this structure, as needed. Please refer to the official Android documentation for more information about supported project file types and directory names.

Compiling and running

To compile your new project in debug mode, simply run rake debug from your project directory:

$ rake debug

# [...]

$ ls -l bin/hello_world-debug.apk

-rw-r--r--   1 user           user        13222 Feb  7 23:16 bin/hello_world-debug.apk

This .apk file may be installed on a connected device or emulator with rake installd. It may even distributed for users to install themselves, though stable versions should be built with the release task.

The official documentation has more details on building. The main difference between Pindah and the standard Ant build is that the Rakefile replaces build.xml as well as all the properties files. The Android Developer page above also explains how to get an emulator running for testing your application.

See Garrett for an example of a basic project.


To contribute to Pindah, you need the required environment setup. You can get tests with the following set of commands.

$ git clone
$ bundle install
$ rake test


Problems? Suggestions? Bring them up on the Mirah mailing list or the #mirah IRC channel on freenode.

See Also

If Mirah is just too low-level for your needs or you simply prefer something more dynamic, you can try Ruboto. Just be warned that it typically incurs a higher performance penalty and requires a larger app memory footprint due to JRuby's runtime.


Released under the Apache 2.0 license.

Copyright (c) 2011 Phil Hagelberg, Nick Plante, J.D. Huntington