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.
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.
Read the introduction article on Medium
See the slides of the latest talk on Speakerdeck
repositories {
maven {
url = uri("https://maven.pkg.github.com/GCX-HCI/ThirtyInch")
}
}
dependencies {
implementation "net.grandcentrix.thirtyinch:thirtyinch:$thirtyinchVersion"
implementation "net.grandcentrix.thirtyinch:thirtyinch-rx2:$thirtyinchVersion"
implementation "net.grandcentrix.thirtyinch:thirtyinch-logginginterceptor:$thirtyinchVersion"
implementation "net.grandcentrix.thirtyinch:thirtyinch-kotlin:$thirtyinchVersion"
implementation "net.grandcentrix.thirtyinch:thirtyinch-kotlin-coroutines:$thirtyinchVersion"
// Legacy dependencies
implementation "net.grandcentrix.thirtyinch:thirtyinch-rx:$thirtyinchVersion"
}repositories {
jcenter()
}
dependencies {
implementation "net.grandcentrix.thirtyinch:thirtyinch:$thirtyinchVersion"
implementation "net.grandcentrix.thirtyinch:thirtyinch-rx2:$thirtyinchVersion"
implementation "net.grandcentrix.thirtyinch:thirtyinch-logginginterceptor:$thirtyinchVersion"
implementation "net.grandcentrix.thirtyinch:thirtyinch-kotlin:$thirtyinchVersion"
implementation "net.grandcentrix.thirtyinch:thirtyinch-kotlin-coroutines:$thirtyinchVersion"
// Lagacy dependencies
implementation "net.grandcentrix.thirtyinch:thirtyinch-rx:$thirtyinchVersion"
}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!");
}
}- survives configuration changes
- survives when the
Activitygot killed in background - is not a singleton
- dies when the
Activitygets finished
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
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);
}
}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);
}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
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 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.
Using Kotlin these days is a no-brainer.
ThirtyInch provides some extension methods to improve itself even further!
When using sendToView, repeating it.* inside the lambda is quite annoying.
It's clear that the methods are called on the view.
With the kotlin extension deliverToView the TiView will be give over to the lambda as this.
class HelloWorldPresenter : TiPresenter<HelloWorldView> {
override fun onCreate() {
// normal java API
sendToView {
it.showText("Hello World")
}
// kotlin extension
deliverToView {
showText("Hello World")
}
}
}
interface HelloWorldView : TiView {
fun showText(text: String)
}Back in the Java days we had to use it inside the sendToView-lambda.
If you're using Kotlin's Coroutines we offer a CoroutineScope that scopes to a presenter's lifecycle.
class HelloWorldPresenter : TiPresenter<HelloWorldView> {
private val scope = TiCoroutineScope(this, Dispatchers.Default)
override fun onCreate() {
scope.launch { ... }
}
}The created Job will automatically be cancelled when the presenter is destroyed.
Alternatively, you can launch jobs that get cancelled when a TiView detaches:
class HelloWorldPresenter : TiPresenter<HelloWorldView> {
private val scope = TiCoroutineScope(this, Dispatchers.Default)
override fun onAttachView(view: HelloWorldView) {
scope.launchUntilViewDetaches { ... }
}
}However, be careful that launchUntilViewDetaches can only be called when there is a view attached!
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());
}
}You can make Disposable handling even less intrusive in Kotlin. Just create the following interface and make your presenters implement it:
interface DisposableHandler {
// Initialize with reference to your TiPresenter instance
val disposableHandler: RxTiPresenterDisposableHandler
// Dispose of Disposables dependent on the TiPresenter lifecycle
fun Disposable.disposeWhenDestroyed(): Disposable = disposableHandler.manageDisposable(this)
// Dispose of Disposables dependent on the TiView attached/detached state
fun Disposable.disposeWhenViewDetached(): Disposable = disposableHandler.manageViewDisposable(this)
} Then just implement the interface in your presenter and you can use created extension functions to manage Disposables:
class MyPresenter : TiPresenter<MyView>(), DisposableHandler {
override val disposableHandler = RxTiPresenterDisposableHandler(this)
override fun onCreate() {
super.onCreate()
// Presenter lifecycle dependent Disposable
myObservable
.subscribe()
.disposeWhenDestroyed()
}
override fun onAttachView(view: MyView) {
super.onAttachView(view)
// View attached/detached dependent Disposable
myViewObservable
.subscribe()
.disposeWhenViewDetached()
}
}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.