ThirtyInch - a MVP library for Android
This library adds Presenters to Activities and Fragments. It favors the stateful Presenter pattern, where the Presenter survives configuration changes and dumb View pattern, where the View only sends user events and receives information from the Presenter but never actively asks for data. This makes testing very easy because no logic lives in the View (Activity, Fragment) except for fancy animations which anyways aren't testable.
The name
Keep Android At Arm’s Length
— Kevin Schultz, Droidcon NYC '14
The perfect distance to the Android Framework is approximately thirty inches, the average length of the human arm, shoulder to fingertips.
Story
Read the introduction article on Medium
See the slides of the latest talk on Speakerdeck
Get it 
ThirtyInch is available via jcenter
dependencies {
def thirtyinchVersion = '0.8.5'
// MVP for activity and fragment
compile "net.grandcentrix.thirtyinch:thirtyinch:$thirtyinchVersion"
// We only provid AppCompat so you have to include it by yourself
compile "com.android.support:appcompat-v7:$appCompatVersion"
// rx (1 or 2) extension
compile "net.grandcentrix.thirtyinch:thirtyinch-rx:$thirtyinchVersion"
compile "net.grandcentrix.thirtyinch:thirtyinch-rx2:$thirtyinchVersion"
compile "net.grandcentrix.thirtyinch:thirtyinch-logginginterceptor:$thirtyinchVersion"
// CompositeAndroid plugin
// When you are using ThirtyInch with the CompositeAndroid extension you have to manually
// include the CompositeAndroid dependency. It has to be the same version as appcompat and
// the support library
compile "net.grandcentrix.thirtyinch:thirtyinch-plugin:$thirtyinchVersion"
// def supportLibraryVersion = '24.2.1' <-- use your own version
compile "com.pascalwelsch.compositeandroid:activity:$supportLibraryVersion"
}
ThirtyInch sample project (work in progress)
There is a sample implementation based on the Android Architecture Blueprints TODO app which can be found here: ThirtyInch sample project (work in progress)
Hello World MVP example with ThirtyInch
HelloWorldActivity.java
public class HelloWorldActivity
extends TiActivity<HelloWorldPresenter, HelloWorldView>
implements HelloWorldView {
private TextView mOutput;
@NonNull
@Override
public HelloWorldPresenter providePresenter() {
return new HelloWorldPresenter();
}
@Override
public void showText(final String text) {
mOutput.setText(text);
}
@Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_hello_world);
mOutput = (TextView) findViewById(R.id.output);
}
}
HelloWorldView.java
public interface HelloWorldView extends TiView {
@CallOnMainThread
void showText(final String text);
}
HelloWorldPresenter.java
public class HelloWorldPresenter extends TiPresenter<HelloWorldView> {
@Override
protected void onAttachView(@NonNull final HelloWorldView view) {
super.onAttachView(view);
view.showText("Hello World!");
}
}
ThirtyInch features
Presenter
- survives configuration changes
- survives when the
Activitygot killed in background - is not a singleton
- dies when the
Activitygets finished
Lifecycle
The TiPresenter lifecycle is very easy.
It can be CREATED and DESTROYED. The corresponding callbacks onCreate() and onDestroy() will be only called once!
The TiView can either be ATTACHED or DETACHED. The corresponding callbacks are onAttachView(TiView) and onDetachView() which maps to onStart() and onStop().
public class MyPresenter extends TiPresenter<MyView> {
@Override
protected void onCreate() {
super.onCreate();
}
@Override
protected void onAttachView(@NonNull final HelloWorldView view) {
super.onAttachView(view);
}
@Override
protected void onDetachView() {
super.onDetachView();
}
@Override
protected void onDestroy() {
super.onDestroy();
}
}
The lifecycle can be observed using TiLifecycleObserver
There is no callback for onResume() and onPause() in the TiPresenter. This is something the view layer should handle. Read more about this here Hannes Dorfmann - Presenters don't need lifecycle events
Configuration
The default behaviour might not fit your needs. You can disable unwanted features by providing a configuration in the TiPresenter constructor.
public class HelloWorldPresenter extends TiPresenter<HelloWorldView> {
public static final TiConfiguration PRESENTER_CONFIG =
new TiConfiguration.Builder()
.setRetainPresenterEnabled(true)
.setCallOnMainThreadInterceptorEnabled(true)
.setDistinctUntilChangedInterceptorEnabled(true)
.build();
public HelloWorldPresenter() {
super(PRESENTER_CONFIG);
}
}
Or globally for all TiPresenters
public class MyApplication extends Application {
@Override
public void onCreate() {
super.onCreate();
TiPresenter.setDefaultConfig(MY_DEFAULT_CONFIG);
}
}
TiView Annotations
Two awesome annotations for the TiView interface made it already into Ti saving you a lot of time.
public interface HelloWorldView extends TiView {
@CallOnMainThread
@DistinctUntilChanged
void showText(final String text);
}
@CallOnMainThread
Whenever you call this method it will be called on the Android main thread. This allows to run code off the main thread but send events to the UI without dealing with Handlers and Loopers.
Requires to be a void method. Works only for TiView interfaces implemented by "Android Views" ( TiActivity, TiFragment).
Enabled by default, can be disabled with the TiConfiguration
@DistinctUntilChanged
When calling this method the View receives no duplicated calls. The View swallows the second call when a method gets called with the same (hashcode) parameters twice.
Usecase: The Presenter binds a huge list to the View. The app loses focus ( onDetachView()) and the exact same Activity instance gains focus again ( onAttachView(view)). The Activity still shows the huge list. The Presenter binds the huge list again to the View. When the data has changed the list will be updated. When the data hasn't changed the call gets swallowed and prevents flickering.
Requires to be a void method and has at least one parameter.
Enabled by default, can be disabled with the TiConfiguration
View binding interceptors
View Annotations only work because ThirtyInch supports interceptors. Add interceptors ( BindViewInterceptor) to TiActivity or TiFragment to intercept the binding process from TiView to TiPresenter. Interceptors are public API waiting for other great ideas.
public class HelloWorldActivity extends TiActivity<HelloWorldPresenter, HelloWorldView>
implements HelloWorldView {
public HelloWorldActivity() {
addBindViewInterceptor(new LoggingInterceptor());
}
}
LoggingInterceptor is available as module and logs all calls to the view.
RxJava
Using RxJava for networking is very often used. Observing a Model is another good usecase where Rx can be used inside of a TiPresenter. The Rx package provides helper classes to deal with Subscription or wait for an attached TiView.
public class HelloWorldPresenter extends TiPresenter<HelloWorldView> {
// add the subscription helper to your presenter
private RxTiPresenterSubscriptionHandler rxHelper = new RxTiPresenterSubscriptionHandler(this);
@Override
protected void onCreate() {
super.onCreate();
// automatically unsubscribe in onDestroy()
rxHelper.manageSubscription(
Observable.interval(0, 1, TimeUnit.SECONDS)
// cache the latest value when no view is attached
// emits when the view got attached
.compose(RxTiPresenterUtils.<Long>deliverLatestToView(this))
.subscribe(uptime -> getView().showPresenterUpTime(uptime))
);
}
@Override
protected void onAttachView(@NonNull final HelloWorldView view) {
super.onAttachView(view);
// automatically unsubscribe in onDetachView(view)
rxHelper.manageViewSubscription(anotherObservable.subscribe());
}
}
CompositeAndroid
Extending TiActivity is probably not what you want because you already have a BaseActivity. Extending all already existing Activities from TiActivity doesn't make sense because they don't use MVP right now. CompositeAndroid uses composition to add a TiPresenter to an Activity. One line adds the TiActivityPlugin and everything works as expected.
public class HelloWorldActivity extends CompositeActivity implements HelloWorldView {
public HelloWorldActivity() {
// Java 7
addPlugin(new TiActivityPlugin<>(
new TiPresenterProvider<HelloWorldPresenter>() {
@NonNull
@Override
public HelloWorldPresenter providePresenter() {
return new HelloWorldPresenter();
}
}
));
// Java 8
addPlugin(new TiActivityPlugin<HelloWorldPresenter, HelloWorldView>(
() -> new HelloWorldPresenter()));
}
}
Yes you have to extend CompositeActivity, but that's the last level of inheritance you'll ever need.
License
Copyright 2016 grandcentrix GmbH Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.