A Journey Through MV Wonderland

@FMuntenescu
A Journey Through MV
Wonderland

@FMuntenescu
Robust, stable, testable,
modular, easy to extend

@FMuntenescu
MV ( C P VM )
Model

@FMuntenescu
MV ( C P VM )
View
Model

@FMuntenescu
Model – View – Controller

@FMuntenescu
Controller
Model
View
1 … 1

@FMuntenescu
Controller
Model
View
User input

@FMuntenescu
Update Model
Controller
Model
View
User input

@FMuntenescu
Update
Update Model
Controller
Model
View
User input

@FMuntenescu
Query latest data
Update
Update Model
Controller
Model
View
User input

@FMuntenescu
Model – View – Controller
in Android

@FMuntenescu
Activity
Controller
Model
View
1 … 1

@FMuntenescu
Inform about input
Controller
Model
View
User input

@FMuntenescu
Update Model
Inform about input
Controller
Model
View
User input

@FMuntenescu
Update
Update Model
Inform about input
Controller
Model
View
User input

@FMuntenescu
Query latest data
Update
Update Model
Inform about input
Controller
Model
View
User input

@FMuntenescu
IView
Controller
Model
View
1 … 1

@FMuntenescu
Who handles UI logic?

@FMuntenescu
class User {
String firstName;
String lastName;
…
}

@FMuntenescu
class User {
String firstName;
String lastName;
…
}
displayName =
lastName + “, “ + firstName

@FMuntenescu
class User {
String firstName; Jane
String lastName; Doe
…
}
displayName = Doe, Jane
lastName + “, “ + firstName

@FMuntenescu
View?
User user = userModel.getUser();
nameTextView.setText(
user.getLastName()
+ ", "
+ user.getFirstName())

@FMuntenescu
Model?
String name = userModel.getDisplayName();
nameTextView.setText(name);

@FMuntenescu
The View knows too much!

@FMuntenescu
Controller ModelView
1 … 1
IView

@FMuntenescu
Presenter ModelView
1 … 1
IView

@FMuntenescu
Model – View – Presenter

@FMuntenescu
Presenter ModelView
1 … 1
IView IPresenter

@FMuntenescu
Contract
Presenter ModelView
1 … 1
IView IPresenter

@FMuntenescu
interface IView {
void setName(String name);
}

@FMuntenescu
IUserModel userModel;
IView view;
Presenter(IUserModel userModel,
IView view) {
this.userModel = userModel;
this.view = view;
}

@FMuntenescu
interface IPresenter {
void onLoad();
}

@FMuntenescu
@Override
public void onLoad() {
User user = userModel.getUser();
String displayName =
user.getFirstName()
+ ", "
+ user.getLastName();
view.setName(displayName);
}

@FMuntenescu
@Mock
@Mock
IView view;
Presenter presenter;
@Before
public void setup() {
…
presenter =
new Presenter(userModel, view);
}

@FMuntenescu
@Test
public void displayName_setOnLoad() {
when(userModel.getUser())
.thenReturn(new User(“Jane”, “Doe”);
presenter.onLoad();
verify(view).setName(“Doe, Jane”);
}

@FMuntenescu
IView view;
Presenter(IUserModel userModel, IView view) {
this.view = view;
}
void onLoad() {
…
}

@FMuntenescu
IView view;
Presenter(IUserModel userModel, IView view) {
this.view = view;
}
void onLoad() {
…
}
Observable<String> getName() {
…
}

@FMuntenescu
class View {
…
viewModel.getName()
.subscribe(name-> setName(name));
…
private void setName(String name){
nameTextView.setText(name);
}

@FMuntenescu
IView view;
Presenter(IUserModel userModel,
IView view) {
userModel = userModel;
view = view;
}

@FMuntenescu
Presenter ModelView
1 … *
IView IPresenter

@FMuntenescu
ViewModel ModelView
1 … *

@FMuntenescu
Model – View – ViewModel

@FMuntenescu
class User {
String firstName;
String lastName;
Date dateOfBirth;
}

@FMuntenescu
class User {
Date dateOfBirth; 04.04.1987
}

@FMuntenescu
class User {
Date dateOfBirth; 04.04.1987
}
Name: Doe, Jane
Age: 29

@FMuntenescu
class ViewModel {
…
}
Observable<Integer> getAge() {
…
}
}

@FMuntenescu
class ViewModel {
Observable<DisplayableUser> getUser() {
…
}
}

@FMuntenescu
class DisplayableUser {
String mName;
int mAge;
}
class ViewModel {
Observable<DisplayableUser> getUser() {
…
}
}

@FMuntenescu
@Mock
ViewModel viewModel;
@Before
void setup() {
…
viewModel = new ViewModel(userModel);
}

@FMuntenescu
@Mock
@Before
public void setup() {
…
viewModel = new ViewModel(userModel);
}

@FMuntenescu
@Test
public void getUser_emitsCorrectValue() {
when(userModel.getUser())
.thenReturn(new User(“Jane”,”Doe”,
new Date(4,4,1987));
viewModel.getUser()
.subscribe(testSubscriber);
testSubscriber.assertValue(expectedUser);
}

@FMuntenescu
Model – View – Presenter
&
Model – View – ViewModel

@FMuntenescu
class Presenter {
void onLoad() {
…
}
}
class ViewModel {
…
}
}

@FMuntenescu
( P | VM )Activity

@FMuntenescu
( P | VM )
Fragment
Activity

@FMuntenescu
( P | VM )
Fragment
Activity
Custom View
Custom View

@FMuntenescu
class View implements IView {
@Inject
Presenter presenter;
…
presenter.onLoad(this);

@FMuntenescu
class View {
@Inject

@FMuntenescu
Fragment
SomeView
AnotherView

@FMuntenescu
<RelativeLayout>
<my.custom.SomeView />
<my.custom.AnotherView />
</RelativeLayout>
Fragment
SomeView
AnotherView

@FMuntenescu
<RelativeLayout>
</RelativeLayout>
Fragment
SomeView
AnotherView
NewView

@FMuntenescu
<RelativeLayout>
<my.custom.NewView />
</RelativeLayout>
Fragment
AnotherView
NewView

@FMuntenescu
How to split Views?

@FMuntenescu
Complexity
Responsibility
Reusability

@FMuntenescu
What goes where?
V ? ( P VM )

@FMuntenescu
Does it contain UI logic?
View( P | VM )
Yes No

@FMuntenescu
( P | VM ) ModelView

@FMuntenescu
How to handle
dependencies between
Views?

@FMuntenescu
Fragment
View 1
View 2

@FMuntenescu
Fragment
View 1
View 2
View 1
View 2

@FMuntenescu
JaneFragment
View 1
View 2
Doe
4.4.1987
CONTINUE

@FMuntenescu
Fragment
View 1
View 2
Model

@FMuntenescu
Fragment Presenter
View 1 Presenter
View 2 Presenter

@FMuntenescu
Fragment ViewModel
View 1 ViewModel
View 2 ViewModel

@FMuntenescu
How to handle Android
lifecycle?

@FMuntenescu
onResume /
onPause

@FMuntenescu
@Override
protected void onResume() {
…
presenter.onLoad();
}
@Override
protected void onPause() {
presenter.onStopLoad();
…
}

@FMuntenescu
@Override
protected void onResume() {
…
viewModel.getDataStream()
.subscribe(…);
}
@Override
protected void onPause() {
// unsubscribe
…
}

@FMuntenescu
onAttachedToWindow /
onDetachedFromWindow

@FMuntenescu
@Override
void onAttachedToWindow() {
presenter.onLoad();
…
}
@Override
void onDetachedFromWindow() {
…
presenter.onStopLoad();
}

@FMuntenescu
@Override
void onAttachedToWindow() {
viewModel.getDataStream()
.subscribe(…);
…
}
@Override
void onDetachedFromWindow() {
…
// unsubscribe
}

@FMuntenescu
onSaveInstanceState /
onRestoreInstanceState

@FMuntenescu
@Override
void onSaveInstanceState(Bundle state) {
state.putAll(
presenter/viewModel.getState());
}
@Override
void onRestoreInstanceState(Bundle state) {
presenter/viewModel
.restoreState(state);
}

@FMuntenescu
@Override
Parcelable onSaveInstanceState() {
// save state
}
@Override
void onRestoreInstanceState(
Parcelable state) {
// restore state
}

@FMuntenescu
MVC vs MVP vs MVVM

@FMuntenescu
Are your Android classes
logic free?

@FMuntenescu
Can you unit test
everything?

@FMuntenescu
Do your classes do one
thing and one thing only?

@FMuntenescu
A Journey Through MV
Wonderland
jobs@upday.com
Google Architecture Blueprints
https://github.com/googlesamples/android-architecture
MVP vs MVVM example
https://github.com/florina-muntenescu/MVPvsMVVM
https://upday.github.io/

A Journey Through MV Wonderland

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A Journey Through MV Wonderland