I'm new to android and this is the first time trying to use MVP pattern in my code ... as I understand so far is that my view should talk to the presenter and the presenter to the model > then the presenter will talk again to view.. I wish I'm right with that !!! as shown below in my simple code example I'm trying to return a result value from the model to the presenter and then I will use this result value in the presenter to decide which method should I call in the view..I have 2 questions and I hope some helps. 1) The enqueue method is working async and the result value will always return empty or fail or whatever.. because it works alone... and when I try to use the execute method instead I'm facing a NetworkOnMainThreadException error... so how can I make the right way ? 2) Is this a right way in using MVP pattern ?
This is the SignupContract class
public class SignupContract {
public interface IView{
void signupSuccess();
void signupFailed(String message);
}
public interface IPresenter{
void signup(UserProfile userProfile);
}
public interface IModel{
String signup(UserProfile userProfile);
}
}
This is the View code..
public class SignupActivity extends AppCompatActivity implements SignupContract.IView {
//some code
@Override
protected void onCreate(Bundle savedInstanceState) {
//some code
createAccountBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//some code
presenter.signup(userProfile);
}
});
}
@Override
public void signupSuccess() {
/*AppUtils.dismissLoadingDialog(SignupActivity.this,"","");*/
Intent intent = new Intent(SignupActivity.this, SigninActivity.class);
startActivity(intent);
finish();
}
@Override
public void signupFailed(String message) {
/*AppUtils.dismissLoadingDialog(SignupActivity.this,"","");*/
AppUtils.showErrorMessage(SignupActivity.this, message);
}
and this is the presenter
public class SignupPresenter implements SignupContract.IPresenter {
SignupContract.IView view;
SignupContract.IModel model;
public SignupPresenter(SignupContract.IView view){
model = new SignupModel();
this.view = view;
}
@Override
public void signup(UserProfile userProfile) {
userProfile = UserProfileCleaner.clean(userProfile, "signup");
UserProfileDTO dto = new UserProfileDTO();
String validationMessage = dto.validateUserProfile(userProfile, "signup");
if(validationMessage != null && !validationMessage.equals("")){
view.signupFailed(validationMessage);
}else{
String signupResult = model.signup(userProfile);
if(signupResult.equals("success")){
view.signupSuccess();
}else {
view.signupFailed(signupResult);
}
}
}
}
and this is the model class
public class SignupModel implements SignupContract.IModel {
private String TAG = "SignupModel";
private String result = "";
@Override
public String signup(UserProfile userProfile) {
final Context context = DKApp.getContext();
ServiceWrapper serviceWrapper = new ServiceWrapper(null);
Call<SignupResponse> userSignUpCall = serviceWrapper.userSignUpCall(userProfile.getUser().getUsername(),
userProfile.getUser().getPassword(),userProfile.getPhoneNumber(), userProfile.getEmailAddress(),
userProfile.getFullName());
userSignUpCall.enqueue(new Callback<SignupResponse>() {
@Override
public void onResponse(Call<SignupResponse> call, Response<SignupResponse> response) {
if( response.body() != null && response.isSuccessful() ){
Log.e(TAG,response.body().toString());
if(response.body().getStatus() == 1){
//some code
result = "success";
}else{
result = response.body().getMessage();
}
}else{
result = context.getResources().getString(R.string.request_failed);
}
}
@Override
public void onFailure(Call<SignupResponse> call, Throwable t) {
Log.e(TAG, "Failure : " + t.toString());
result = context.getResources().getString(R.string.request_failed);
}
});
return result;
}
}
You are making a asynchronous call in the model which may take 100ms or 2-4sec so getting signupResult from it like String signupResult = model.signup(userProfile);this is wrong.
Changes you will require :
1) Add onComplete method to IPresenter and change IModel
public interface IPresenter{
void signup(UserProfile userProfile);
//add
void onComplete(String signUpresult);
}
public interface IModel{
//changed
void signup(UserProfile userProfile);
}
2) In your SignupPresenter pass the instance of presenter to model
public class SignupPresenter implements SignupContract.IPresenter {
..
public SignupPresenter(SignupContract.IView view){
model = new SignupModel(this);
this.view = view;
}
...
@Overrides
public void onComplete(String signupResult){
if(signupResult.equals("success")){
view.signupSuccess();
}else {
view.signupFailed(signupResult);
}
}
...
}
3) In your SignupModel once the result is aquired call onComplete(//result) from the presenter
public class SignupModel implements SignupContract.IModel {
SignupPresenter presenter;
public SignupModel(SignupPresenter presenter){
this.presenter = presenter
}
@Override
public void signup(UserProfile userProfile) {
...
userSignUpCall.enqueue(new Callback<SignupResponse>() {
@Override
public void onResponse(Call<SignupResponse> call, Response<SignupResponse> response) {
if(response.body() != null && response.isSuccessful() ){
if(response.body().getStatus() == 1){
//some code
presenter.onComplete("success");
}else{
presenter.onComplete(response.body().getMessage());
}
}else{
presenter.onComplete(context.getResources().getString(R.string.request_failed));
}
}
@Override
public void onFailure(Call<SignupResponse> call, Throwable t) {
Log.e(TAG, "Failure : " + t.toString());
presenter.onComplete(context.getResources().getString(R.string.request_failed));
}
});
}
}
Needful : Show progress dialogue when signup is called and dismiss the same on onComplete in SignupPresenter.
Your understanding is quite good also know that the model should talk with presenter as well. To know more about MVP design pattern read this