learning-machine-android

Blockcerts Android application by Learning Machine

Build variants

Gradle allows us to define different product variants. Each has a separate app id and can be installed simultaneously. Currently they all use the Bitcoin main net and do not differ all that much. Production has an empty logging tree.

• dev
  • App id: com.learningmachine.android.app.dev
  • Dimension: env
• staging
  • App id: com.learningmachine.android.app.staging
  • Dimension: env
• production
  • App id: com.learningmachine.android.app
  • Dimension: env

Running Tests

sh scripts/run_tests.sh

At the time of writing it seems Robolectric is not compatible with JDK > 13 (https://github.com/robolectric/robolectric/issues/5863)

Building APKs

sh scripts/GenerateReleaseBuild.command Answer the prompts as they come. Blockcerts team members: password is stored in regular password manager.

Glossary

Conventions

The following are guidelines for this Android project.

Classes

• Naming
  • Suffix with the type of class: Activity, Fragment, Listener, ListItemView, Manager
  • Prefix member variables with m.
  • If a variable is a view, consider suffixing with the type: mPasswordEditText, mLoginButton
  • Boolean member variables should reflect state (mLocked) and have getters using isState() (ie: isLocked)
• Extract common elements to a superclass to avoid duplication.
• Prefer abstract methods in super over implicit setup in subclass constructors.
• The suggested template below should guide naming:

public class TemplateFragment {

    private static final String ARG_CONSTANT = "TemplateFragment.Constant";

    private List<Object> mObjects;

    /* static methods */

    public static TemplateFragment newInstance() {
        return new TemplateFragment();
    }

    /* lifecycle overrides, onSavedInstanceState, options menu, onActivityResult */

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mObjects = new ArrayList<Object>();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
        // databinding & init
        initView();
    }

    /* private methods */

    private void initView() {}

    private void setupData() {}

    /* getters, setters, and other public methods */

    public List<Object> getObjects() {
        return mObjects;
    }

    public void setObjects(List<Objects> objects) {
        mObjects = objects;
    }

    /* enums */

    protected enum ObjectItemType {
        ITEM_TYPE_A,
        ITEM_TYPE_B,
    }

    /* inner classes */

    private class TemplateListAdapter extends ArrayAdapter<ObjectItemType> {

        public EnergyListAdapter(List<ObjectItemType> items) {
            super(getActivity(), 0, items);
        }
    }

    /* base class overrides */

    @Override
    protected boolean usesInjection() {
        return true;
    }
}

We suggest the following method orgainization:

1. newInstance and other static methods

• lifecycle, onSavedInstanceState, options menu, onActivityResult
• private methods
• all other protected methods (including immediate parent overrides)
• all other public methods(including immediate parent overrides)
• enums
• defined interfaces
• inner classes
• base overrides

Layout files

• Naming
  • Reverse DNS style.
  • Prefix with the type of layout: activity_login, fragment_login, list_item_login
  • Describe widgets and suffix with the type: login_username_text_view
• Use auto format for consistency.
• Prefer /> over open and close tags that do not contain children.
• Extract strings and dimensions to their respective xml resources. 0dp is an exception and should remain in the layout file.
• Use styles when possible.
• id's should come first for easy element identification, and be on a new line. Enable Preferences > Code Style > XML > Android > Insert Line break before first attribute to help format your layout files properly.

strings.xml

• Naming
  • Describe where it is used: fragment_login_username_hint
  • For long strings, append _message: "We would like to welcome you to this app because it is amazing" becomes fragment_login_welcome_message
  • If error, append _error_message: "Failed to login" would be login_error_message
• Formatted strings
  • Use the recommended pattern: %1$s
  • Use the correct type for the data it will be formatting: s, d, f, etc.

Managers

• Responsibilities

  • Loading and providing data
  • Creating success and failure callbacks
  • Fetching / pushing data from / to the WebService

• Prefix data operations with load, this signifies an asynchronous call (i.e. webservice or database)

• Prefix direct data accessors with get. These methods will synchronously return data directly to the caller.

Stores

• Controllers (i.e. Activities and Fragments) should never access Stores directly. All requests to load or get data should be relayed through a Manager.

Interfaces / Callbacks

• We like and make extensive use of these.
• They are a great way to enforce implementation of something a calling class may need.

Blockcerts Libraries

Cert-verifier-js

• Javascript library for verifying Blockcerts Certificates

Updating cert-verifier-js to a new version

Pull down the cvjs repository:

https://github.com/blockchain-certificates/cert-verifier-js.git && cd cert-verifier-js

CVJS requires an npm token, so create one on npm

export NPM_TOKEN={insert token here}

Install

npm install

Generate build

npm run-script build

Copy content of /dist/verifier-iife.js

Paste in this android project at this location: wallet-android/LearningMachine/app/src/main/assets/www/verifier.js

External Libraries

Autolinker.js

• Utility to convert urls found in HTML into links
• Minified javascript included as a static asset in the www directory of the app
• MIT

BitcoinJ

• Java implementation of the Bitcoin protocol
• Forked by uniquid to allow creation of wallets with arbitrary path (e.g m/44'/0'/0/0)
• Apache License

SLF4J

• Simple Logging Facade for Java
• Required by BitcoinJ
• MIT

Spongy Castle

• Repackage of Bouncy Castle for Android
• Required by BitcoinJ
• MIT X11

Protobuf

• Google's language-neutral, platform-neutral, extensible mechanism for serializing structured data
• Required by BitcoinJ
• License

Dagger 2

• Dependency injection framework
• Apache 2.0

Timber

• A logger with a small, extensible API which provides utility on top of Android's normal Log class
• Apache 2.0

JodaTime Android

• A version of Joda-Time built with Android in mind
• Apache 2.0

Retrofit

• A type-safe REST client for Android and Java
• Apache 2.0

Okhttp

• An HTTP+HTTP/2 client for Android and Java applications
• Apache 2.0

Gson

• JSON object converter and parser
• Apache 2.0

RxJava

• RxJava bindings for Android
• Apache 2.0

RxLifecycle

• Automatically complete sequences based on a second lifecycle stream
• Apache 2.0

RxLint

• A set of lint checks that check your RxJava code
• Apache 2.0

Picasso

• Image loading and caching
• Apache 2.0

Guava

• Google Core Libraries for Java
• Apache 2.0

JUnit

• A simple framework to write repeatable tests.
• Eclipse Public License - v 1.0

Mockito

• Tasty mocking framework for unit tests in Java
• MIT

Robolectric

• Unit testing framework
• MIT

JodaTime

• A quality replacement for the Java date and time classes
• Required for unit tests
• Apache 2.0

Contact

Contact us at the Blockcerts community forum.