Develop Reference

Cannot observe LiveData from parent Activity

I created an abstract GlobalActivity extending AppCompatActivity and a GlobalViewModel extending ViewModel, in order to have some LiveData always ready to show Dialog messages and Toast messages, as well as displaying and hiding a ProgressBar. Problem is that the LoginActivity is not observing the LiveData object I mentioned above, so is not reacting to changes nor calls. Here is my code:
GlobalActivity:
public abstract class GlobalActivity extends AppCompatActivity {
protected GlobalViewModel mGlobalViewModel = new GlobalViewModel();
private Consumer<Throwable> errorHandler = throwable -> {
Timber.e(throwable);
DialogUtils.showOneButtonDialog(this, R.string.unexpected_error, null);
};
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
RxJavaPlugins.setErrorHandler(this.errorHandler);
setUpBasicViewModel();
mGlobalViewModel.getDialogMessage().observe(this, mssg -> DialogUtils.showOneButtonDialog(GlobalActivity.this, mssg, null));
mGlobalViewModel.getToastMessage().observe(this, mssg -> DialogUtils.showMessage(mssg));
mGlobalViewModel.getIsLoading().observe(this, bool -> setLoadingState(bool));
}
public abstract void setLoadingState(boolean bool);
public abstract void setUpBasicViewModel();
}
GlobalViewModel:
public class GlobalViewModel extends ViewModel {
protected MutableLiveData<String> dialogMessage = new MutableLiveData<>();
protected MutableLiveData<String> toastMessage = new MutableLiveData<>();
protected SingleLiveEvent<Boolean> isLoading = new SingleLiveEvent<>();
public GlobalViewModel(){}
public MutableLiveData<String> getDialogMessage() {
return dialogMessage;
}
public MutableLiveData<String> getToastMessage() {
return toastMessage;
}
public SingleLiveEvent<Boolean> getIsLoading() {
return isLoading;
}
}
LoginActivity:
public class LoginActivity extends GlobalActivity {
private LoginViewModel mLoginViewModel;
private ActivityLoginBinding mDataBinding;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mLoginViewModel = new ViewModelProvider(this, new LoginViewModelFactory()).get(LoginViewModel.class);
mDataBinding = DataBindingUtil.setContentView(this, R.layout.activity_login);
mDataBinding.setLifecycleOwner(this);
mDataBinding.setViewModel(mLoginViewModel);
}
#Override
public void setLoadingState(boolean bool) {
mDataBinding.progressBar.setVisibility(mDataBinding.progressBar.isShown() ? View.GONE : View.VISIBLE);
}
#Override
public void setUpBasicViewModel() {
mGlobalViewModel = ViewModelProviders.of(this).get(GlobalViewModel.class);
}
...
}

My Class in not an enclossing class

so I have class constructor:
public class HealthDataStore { // this class is 3rd party api - can't modify
public HealthDataStore(Context context, HealthDataStore.ConnectionListener listener){ /* bla... */ }
/* bla... */
// with Listener Interface:
public interface ConnectionListener {
void onConnected();
void onConnectionFailed(HealthConnectionErrorResult var1);
void onDisconnected();
}
}
and in my repository class i have:
public class HealthRepository {
private string DSConnectionStatus;
public void connectDataStore(HealthDSConnectionListener listener) {
mStore = new HealthDataStore(app, listener);
mStore.connectService();
}
// with inner class:
public class HealthDSConnectionListener implements HealthDataStore.ConnectionListener{
#Override public void onConnected() { DSConnectionStatus = "Connected"; }
#Override public void onConnectionFailed(HealthConnectionErrorResult healthConnectionErrorResult) { DSConnectionStatus = "Connection Failed"; }
#Override public void onDisconnected() { DSConnectionStatus = "Disconnected"; }
};
}
and in my view model class i have below object:
public class SplashViewModel extends AndroidViewModel {
public void connectRepoDataStore(){
// repo is object of class HealthRepository
repo.connectDataStore(mConnectionListener)
// other things to do here
}
private final HealthRepository.HealthDSConnectionListener mConnectionListener = new HealthRepository.HealthDSConnectionListener(){
#Override public void onConnected() {
super.onConnected(); // i need this super to set DSConnectionStatus value
// other things to do here
}
#Override public void onConnectionFailed(HealthConnectionErrorResult error) {
super.onConnectionFailed(error); // i need this super to set DSConnectionStatus value
// other things to do here
}
#Override public void onDisconnected() {
super.onDisconnected(); // i need this super to set DSConnectionStatus value
// other things to do here
}
}
why is private final HealthRepository.HealthDSConnectionListener mConnectionListener = new HealthRepository.HealthDSConnectionListener() throw me error that the class is not enclosing class?
then how should i achieve this? to have my final listener class have capability to set DSConnectionStatus in healthrepository class?

Always try to avoid using inner classes if you know you'll have to extend them. Instead use a separate class, and swap the outer class with a field. If you need to modify a private field that you do not want to expose then create a package-private setter.
public class HealthRepository {
private String DSConnectionStatus;
public void connectDataStore(HealthDSConnectionListener listener) {
mStore = new HealthDataStore(app, listener);
mStore.connectService();
}
void setConnectionStatus(String status) {
DSConnectionStatus = status;
}
}
// create another class in the same package
public class HealthDSConnectionListener implements HealthDataStore.ConnectionListener {
private final HealthRepository repo;
public HealthDSConnectionListener(HealthRepository repo) {
this.repo = repo;
}
#Override public void onConnected() { repo.setConnectionStatus("Connected"); }
#Override public void onDisconnected() { repo.setConnectionStatus("Disconnected"); }
#Override public void onConnectionFailed(HealthConnectionErrorResult error) {
repo.setConnectionStatus("Connection Failed");
}
};
public class SplashViewModel extends AndroidViewModel {
private final HealthRepository repo;
public void connectRepoDataStore() {
// repo is object of class HealthRepository
repo.connectDataStore(mConnectionListener)
// other things to do here
}
private final HealthDSConnectionListener mConnectionListener = new HealthDSConnectionListener(repo) {
#Override public void onConnected() {
super.onConnected();
// ...
}
#Override public void onConnectionFailed(HealthConnectionErrorResult error) {
super.onConnectionFailed(error);
// ...
}
#Override public void onDisconnected() {
super.onDisconnected();
// ...
}
}
}

Communication between Class and Activity via Interface

I have the MainActivity that a want to communicate with a class using an interface.
public interface MyInterface(){
public void doAction();
}
In my MainActivity I will have this piece of code:
public class MainActivity extends AppCompatActivity implements MyInterface(){
//....some more code here
#Override
public void doAction() {
//any code action here
}
//....some more code here
}
So now, If I have another class (NOT ACTIVITY), how should I correctly make the link between class---interface---mainActivity??
public class ClassB {
private MyInterface myinterface;
//........
//...... how to initialize the interface
}
I am confused about how to initialize and use the interface in ClassB

In the constructor of other class: ClassB, accept interface as argument and pass reference of Activity, hold that object in your Activity.
like so:
public class MainActivity extends AppCompatActivity implements MyInterface()
{
private ClassB ref; // Hold reference of ClassB directly in your activity or use another interface(would be a bit of an overkill)
#Override
public void onCreate (Bundle savedInstanceState) {
// call to super and other stuff....
ref = new ClassB(this); // pass in your activity reference to the ClassB constructor!
}
#Override
public void doAction () {
// any code action here
}
}
public class ClassB
{
private MyInterface myinterface;
public ClassB(MyInterface interface)
{
myinterface = interface ;
}
// Ideally, your interface should be declared inside ClassB.
public interface MyInterface
{
// interface methods
}
}
FYI, this is also how View and Presenter classes interact in MVP design pattern.

public class MainActivity extends AppCompatActivity implements
MyInterface
{
OnCreate()
{
ClassB classB= new ClassB(this);
}
}
public class ClassB
{
private MyInterface myinterface;
public ClassB(MyInterface myinterface)
{
this.myinterface=myinterface;
}
void anyEvent() // like user click
{
myinterface.doAction();
}
}

public class MainActivity extends AppCompatActivity implements MyInterface(){
private ClassB ref;
#Override
public void onCreate (Bundle savedInstanceState) {
ref = new ClassB();
ref.setMyinterface(this);
}
#Override
public void doAction () {
// any code action here
}
}
public class ClassB{
private MyInterface myinterface;
public setMyInterface(MyInterface interface){
myinterfece = interface;
}
public interface MyInterface{
// interface methods
}
}

//-------------------------------------
//Two way communication using Interface
//-------------------------------------
//A. Interfaces
//Communicator Interface ( Activity to Fragment )
public interface CommunicateToFragment {
public void CallBack(String name);
}
// Communicator Interface ( Fragment to Main )
public interface CommunicateToMain {
public void respond(String data);
}
//B. Main Class implements CommunicateToMain Interface
//Use CommunicateToFragment interface to send data in FragmentA
public class MainActivity extends AppCompatActivity implements CommunicateToMain {
private CommunicateToFragment communicateToFragment;
public void setCommunicateToFragment(CommunicateToFragment communicateToFragment) {
this.communicateToFragment = communicateToFragment;
}
#Override
protected void onCreate (Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
public void respond (String data) {
communicateToFragment.CallBack("Callbacked when onCreate method Created" + data);
Log.d("test","get result from fragment: " + data);
FragmentManager manager = getFragmentManager();
FragmentB f2 = (FragmentB) manager.findFragmentById(R.id.id_fragment2);
f2.changeText(data);
}
}
//C. FragmentA implements CommunicateToFragment
//Use CommunicateToMain interface to send data in MainActivity
public class FragmentA extends Fragment implements View.OnClickListener, CommunicateToFragment{
Button button;
int counter=0;
CommunicateToMain commToMain;
#Nullable
#Override
public View onCreateView (LayoutInflater inflater, #Nullable ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_a,container,false);
}
#Override
public void onActivityCreated (#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
commToMain = (CommunicateToMain) getActivity();
button = getActivity().findViewById(R.id.button);
button.setOnClickListener(this);
if(getActivity() instanceof MainActivity){
((MainActivity) getActivity()).setCommunicateToFragment(this);
}
}
#Override
public void onClick (View view) {
counter++;
commToMain.respond("The button was clicked" + counter + " Times");
}
#Override
public void CallBack(String name) {
Log.d("test","get result from main activity: " + name);
}
}

Android Extend double class

I have my Class Adapter , and I need to have the access of two class ! Then I can put public class JSONAdapter extends ArrayAdapter<Voiture> { for have access in my class " Voiture " but I need to have the acceesss in my class "Moniteur" too , and I can"t put that :
public class JSONAdapter extends ArrayAdapter<Voiture>,ArrayAdapter<Moniteur> {
I need to view attributes of my class " Voiture " and " Moniteur " ...
Do you have the solution for me please ? Thanks
EDIT : Ok thanks you , this is the code of my class VOITURE :
public class Voiture {
private int idV = -1; // permet de voir si le parent est enregistré dans la BDD
private String marqueV;
private String dateAchatV;
private String PlaqueImmatriculationV;
public Voiture(String marqueV, String plaqueImmatriculationV) {
this.marqueV = marqueV;
PlaqueImmatriculationV = plaqueImmatriculationV;
}
public Voiture(JSONAdapter jsonAdapter) {
this.marqueV = marqueV;
this.PlaqueImmatriculationV = PlaqueImmatriculationV;
}
public int getIdV() {
return idV;
}
public void setIdV(int idV) {
this.idV = idV;
}
public String getMarqueV() {
return marqueV;
}
public void setMarqueV(String marqueV) {
this.marqueV = marqueV;
}
public String getDateAchatV() {
return dateAchatV;
}
public void setDateAchatV(String dateAchatV) {
this.dateAchatV = dateAchatV;
}
public String getPlaqueImmatriculationV() {
return PlaqueImmatriculationV;
}
public void setPlaqueImmatriculationV(String plaqueImmatriculationV) {
PlaqueImmatriculationV = plaqueImmatriculationV;
}
}
This is the code of my class Moniteur :
public class Moniteur {
private int idM;
private String nomM;
private String prenomM;
private String adresseM;
private String telephoneM;
public Moniteur(String nomM, String prenomM,String adresseM,String telephoneM) {
this.nomM = nomM;
this.prenomM = prenomM;
this.adresseM = adresseM;
this.telephoneM = telephoneM;
}
public int getIdM() { return idM; }
public void setIdM(int idM) { this.idM = idM; }
public String getNomM() {
return nomM;
}
public void setNomM(String nomM) {
this.nomM = nomM;
}
public String getPrenomM() {
return prenomM;
}
public void setPrenomM(String prenomM) {
this.prenomM = prenomM;
}
public String getAdresseM() {
return adresseM;
}
public void setAdresseM(String adresseM) {
this.adresseM = adresseM;
}
public String getTelephoneM() {
return telephoneM;
}
public void setTelephoneM(String telephoneM) {
this.telephoneM = telephoneM;
}
}

The purpose of these two classes and how they relate is not clear, but if you want to store both of them in a single container (which is what you are trying to do) you will need to define a common interface between them (or an abstract class). I don't speak French so you will have a easier time creating a good name.
I suggest creating an interface:
public interface AbstractItem
{
//TODO define common functions in this class
}
then implement this interface in your classes:
public class Voiture implements AbstractItem
{ ... }
public class Moniteur implements AbstractItem
{ ... }
Then, you can create an array adapter that will hold both of these items:
public class JSONAdapter extends ArrayAdapter<AbstractItem>
{ ... }

If I understand correctly, "Voiture" means "car" and "Moniteur" means "instructor" or "teacher".
So, it sounds like you are implementing a type of "driving school" where there are teachers with cars that they use/drive.
If that is the case, you really only need an ArrayAdapter<Monituer> and you could implement your Moniteur class like so.
public class Moniteur {
private List<Voiture> voitures;
public Monituer() {
voitures = new ArrayList<Voiture>();
}
public void ajouterVoiture(Voiture v) {
voitures.add(v);
}
public List<Voiture> obtientVoitures() {
return voitures;
}
}
Or maybe I don't understand what is trying to be displayed in the adapters. In that case, feel free to comment below.

Adding Functionality to both Android's Activity (parent class) and FragmentActivity (child class) in best coding style (minimal duplication)

In Android Library, FragmentActivity extends Activity. I would like to add a few methods, and override some methods, of the original Activity.
import android.app.Activity
public class Activiti extends Activity {
public void myNewMethod() { ... }
}
Because of the original hierarchy, FragmentActivity extends Activity, myNewMethod() should also be present in my library's FragmentActiviti
import android.support.v4.app.FragmentActivity;
public abstract class FragmentActiviti extends FragmentActivity {
public void myNewMethod() { ... }
}
But this will lead to a duplication of code, which i do not want this happens. Is there a way to avoid this duplication?
Edit: Usage scenario
Activiti.java
public abstract class Activiti extends Activity {
private int current_orientation = Configuration.ORIENTATION_UNDEFINED; // ORIENTATION_UNDEFINED = 0
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
current_orientation = this.getResources().getConfiguration().orientation;
}
protected boolean isDevicePortrait() { return current_orientation == Configuration.ORIENTATION_PORTRAIT; }
}
FragmentActiviti.java
public abstract class FragmentActiviti extends FragmentActivity {
/* This onCreate() can be omitted. Just putting here explicitly. */
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
protected void someUtilsForFragments() { /* not used yet */ }
}
E_fragtest_06.java
public class E_fragtest_06 extends FragmentActiviti {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
System.out.printf(isDevicePortrait()); // this NOT WORK for now
}
}
Edit 2: Try using Util class
i think using the Decorator Class would be the most nicest way to solve this problem (no duplication of code). But the Decorator Pattern is just a bit hard (or impossible) to apply on Android Activity scenario.
i try implementing #hazzik's approach, but i still experience some problems.
ActivityUtil.java
public abstract class ActivityUtil {
private int current_orientation = Configuration.ORIENTATION_UNDEFINED; // ORIENTATION_UNDEFINED = 0
public void onCreate(Activity activity, Bundle savedInstanceState) {
activity.onCreate(savedInstanceState);
current_orientation = activity.getResources().getConfiguration().orientation;
}
public boolean isDevicePortrait() { return current_orientation == Configuration.ORIENTATION_PORTRAIT; }
}
Activiti.java
public class Activiti extends Activity {
private ActivityUtil activityUtil;
#Override
public void onCreate(Bundle savedInstanceState) {
activityUtil.onCreate(this, savedInstanceState);
}
protected boolean isDevicePortrait() { return activityUtil.isDevicePortrait(); }
}
FragmentActiviti.java
public abstract class FragmentActiviti extends FragmentActivity {
private ActivityUtil activityUtil;
#Override
public void onCreate(Bundle savedInstanceState) {
activityUtil.onCreate(this, savedInstanceState);
}
protected boolean isDevicePortrait() { return activityUtil.isDevicePortrait(); }
}
In ActivityUtil.onCreate(), activity.onCreate(savedInstanceState); is causing this compile error:
The method onCreate(Bundle) from the type Activity is not visible.
If i change Activity to Activiti:
public abstract class ActivityUtil {
public void onCreate(Activiti activity, Bundle savedInstanceState) { ... }
...
}
It will lead to another compile error in FragmentActiviti.onCreate()'s activityUtil.onCreate():
The method onCreate(Activiti, Bundle) in the type ActivityUtil is not applicable for the arguments (FragmentActiviti, Bundle)
i understand why those errors occur. But i just don't know how to avoid them.
To thanks all the guys who have been contributing to this question, especially #flup for guiding me about the Decorator Pattern, #hazzik and #donramos for your extensive efforts, i m here posting
My enhanced Android's Activity and FragmentActivity classes.
If you are also developing Android applications, i hope my codes could help you guys in some ways :-)
ActivityCore.java
package xxx.android;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.res.Configuration;
import android.os.Bundle;
public final class ActivityCore {
public interface ActivityCallbackInterface {
public void onCreateCallback(Bundle savedInstanceState);
public void onBeforeSaveInstanceState(Bundle outState);
public void onSaveInstanceStateCallback(Bundle outState);
}
private final Activity activity;
/**
* This current_orientation variable should be once set, never changed during the object life-cycle.
* But Activity.getResources() is not yet ready upon the object constructs.
* That's why THIS CLASS is wholly responsible to maintain THIS VARIABLE UNCHANGED.
*/
private int current_orientation = Configuration.ORIENTATION_UNDEFINED; // ORIENTATION_UNDEFINED = 0
public ActivityCore(Activity activity) { this.activity = activity; }
public void onCreate(Bundle savedInstanceState) {
((ActivityCallbackInterface) activity).onCreateCallback(savedInstanceState);
current_orientation = activity.getResources().getConfiguration().orientation;
}
public void onSaveInstanceState(Bundle outState) {
/**
* THIS is the best ever place i have found, to unload unwanted Fragments,
* thus prevent re-creating of un-needed Fragments in the next state of Activity.
* (state e.g. Portrait-to-Landscape, or Landscape-to-Portrait)
*
* The KEY is to do it BEFORE super.onSaveInstanceState()
* (my guess for this reason is, in super.onSaveInstanceState(),
* it saves the layout hierarchy, thus saved the Fragments into the Bundle also.
* Thus restored.
* Note that Fragments NOT IN LAYOUT, having ONLY TAGS, are also restored.)
*/
((ActivityCallbackInterface) activity).onBeforeSaveInstanceState(outState);
((ActivityCallbackInterface) activity).onSaveInstanceStateCallback(outState);
}
public int getCurrentOrientation() { return current_orientation; }
public boolean isDevicePortrait() { return current_orientation == Configuration.ORIENTATION_PORTRAIT; }
public boolean isDeviceLandscape() { return current_orientation == Configuration.ORIENTATION_LANDSCAPE; }
public boolean isNewDevicePortrait() { return activity.getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT; }
public boolean isNewDeviceLandscape() { return activity.getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE; }
public boolean isPortrait2Landscape() { return isDevicePortrait() && isNewDeviceLandscape(); }
public boolean isLandscape2Portrait() { return isDeviceLandscape() && isNewDevicePortrait(); }
public String describeCurrentOrientation() { return describeOrientation(current_orientation); }
public String getCurrentOrientationTag() { return getOrientationTag(current_orientation); }
public String describeNewOrientation() { return describeOrientation(activity.getResources().getConfiguration().orientation); }
public String getNewOrientationTag() { return getOrientationTag(activity.getResources().getConfiguration().orientation); }
private String describeOrientation(final int orientation) {
switch (orientation) {
case Configuration.ORIENTATION_UNDEFINED: return "ORIENTATION_UNDEFINED"; // 0
case Configuration.ORIENTATION_PORTRAIT: return "ORIENTATION_PORTRAIT"; // 1
case Configuration.ORIENTATION_LANDSCAPE: return "ORIENTATION_LANDSCAPE"; // 2
case Configuration.ORIENTATION_SQUARE: return "ORIENTATION_SQUARE"; // 3
default: return null;
}
}
#SuppressLint("DefaultLocale")
private String getOrientationTag(final int orientation) {
return String.format("[%d:%s]", orientation, describeOrientation(orientation).substring(12, 16).toLowerCase());
}
}
Activity.java
package xxx.android.app;
import xxx.android.ActivityCore;
import xxx.android.ActivityCore.ActivityCallbackInterface;
import android.os.Bundle;
public abstract class Activity extends android.app.Activity implements ActivityCallbackInterface {
private final ActivityCore activityCore;
public Activity() { super(); activityCore = new ActivityCore(this); }
#Override
protected void onCreate(Bundle savedInstanceState) { activityCore.onCreate(savedInstanceState); }
#Override public void onCreateCallback(Bundle savedInstanceState) { super.onCreate(savedInstanceState); }
#Override
public void onBeforeSaveInstanceState(Bundle outState) {} // Optionally: let child class override
#Override
protected void onSaveInstanceState(Bundle outState) { activityCore.onSaveInstanceState(outState); }
#Override public void onSaveInstanceStateCallback(Bundle outState) { super.onSaveInstanceState(outState); }
public final int getCurrentOrientation() { return activityCore.getCurrentOrientation(); }
public final boolean isDevicePortrait() { return activityCore.isDevicePortrait(); }
public final boolean isDeviceLandscape() { return activityCore.isDeviceLandscape(); }
public final boolean isNewDevicePortrait() { return activityCore.isNewDevicePortrait(); }
public final boolean isNewDeviceLandscape() { return activityCore.isNewDeviceLandscape(); }
public final boolean isPortrait2Landscape() { return activityCore.isPortrait2Landscape(); }
public final boolean isLandscape2Portrait() { return activityCore.isLandscape2Portrait(); }
public final String describeCurrentOrientation() { return activityCore.describeCurrentOrientation(); }
public final String getCurrentOrientationTag() { return activityCore.getCurrentOrientationTag(); }
public final String describeNewOrientation() { return activityCore.describeNewOrientation(); }
public final String getNewOrientationTag() { return activityCore.getNewOrientationTag(); }
}
FragmentActivity.java
package xxx.android.support.v4.app;
import xxx.android.ActivityCore;
import xxx.android.ActivityCore.ActivityCallbackInterface;
import android.os.Bundle;
public abstract class FragmentActivity extends android.support.v4.app.FragmentActivity implements ActivityCallbackInterface {
private final ActivityCore activityCore;
public FragmentActivity() { super(); activityCore = new ActivityCore(this); }
#Override
protected void onCreate(Bundle savedInstanceState) { activityCore.onCreate(savedInstanceState); }
#Override public void onCreateCallback(Bundle savedInstanceState) { super.onCreate(savedInstanceState); }
#Override
public void onBeforeSaveInstanceState(Bundle outState) {} // Optionally: let child class override
#Override
protected void onSaveInstanceState(Bundle outState) { activityCore.onSaveInstanceState(outState); }
#Override public void onSaveInstanceStateCallback(Bundle outState) { super.onSaveInstanceState(outState); }
public final int getCurrentOrientation() { return activityCore.getCurrentOrientation(); }
public final boolean isDevicePortrait() { return activityCore.isDevicePortrait(); }
public final boolean isDeviceLandscape() { return activityCore.isDeviceLandscape(); }
public final boolean isNewDevicePortrait() { return activityCore.isNewDevicePortrait(); }
public final boolean isNewDeviceLandscape() { return activityCore.isNewDeviceLandscape(); }
public final boolean isPortrait2Landscape() { return activityCore.isPortrait2Landscape(); }
public final boolean isLandscape2Portrait() { return activityCore.isLandscape2Portrait(); }
public final String describeCurrentOrientation() { return activityCore.describeCurrentOrientation(); }
public final String getCurrentOrientationTag() { return activityCore.getCurrentOrientationTag(); }
public final String describeNewOrientation() { return activityCore.describeNewOrientation(); }
public final String getNewOrientationTag() { return activityCore.getNewOrientationTag(); }
}
Lastly, i really have to thanks you guys are being so so so helpful and keep updating the solving progress with me! You all are the key persons who make stackoverflow a perfect site for programmers. Should you spot any problems in my codes, or any rooms for improvements, please do not hesitate to help me again :-)
Some improvements?
It is because onBeforeSaveInstanceState() is implemented upon usage, all the three classes need to keep abstract. This leads to a duplication of the member variable current_orientation. If current_orientation could be put into class ActivityBase, or grouping it into somewhere else, it would be a lot nicer!
stupid me. i have fixed it :-)

For my point of view the best solution here is to delegate logic to some class, let's call it CustomActivityLogic.
Also you need to create common interface (CustomActivity) for your activities if you want to access some data or methods of activity classes from your logic class.
To call protected virtual overridden methods there are two solutions:
call method of supper from overridden method
make a new method in subclass and call super method from this new method. Call new method from shared logic.
CustomActivity.java
public interface CustomActivity {
void someMethod();
}
Activiti.java
import android.app.Activity
public class Activiti
extends Activity
implements CustomActivity {
private CustomActivityLogic logic = new CustomActivityLogic();
public void someMethod() { /***/ }
public void myNewMethod() { logic.myNewMethod(this); }
#Override
protected void onCreate(Bundle savedInstanceState) {
logic.onCreate(this, savedInstanceState); // call shared logic
super.onCreate(savedInstanceState); // call super
}
}
FragmentActivitii.java
import android.support.v4.app.FragmentActivity;
public class FragmentActivitii
extends FragmentActivity
implements CustomActivity {
private CustomActivityLogic logic = new CustomActivityLogic();
public void someMethod() { /***/ }
public void myNewMethod() { logic.myNewMethod(this); }
#Override
protected void onCreate(Bundle savedInstanceState) {
logic.onCreate(this, savedInstanceState); // call shared logic
super.onCreate(savedInstanceState); // call super
}
}
CustomActivityLogic.java
public class CustomActivityLogic {
public void myNewMethod(CustomActivity activity) { /*...*/ }
public void onCreate(Activity activity, Bundle savedInstanceState) {
/* shared creation logic */
}
}
Approach with making onCreate available to call from outside via CustomActivity interface
CustomActivity.java
public interface CustomActivity {
void someMethod();
void onCreateSuper(Bundle savedInstanceState);
}
Activiti.java
import android.app.Activity
public class Activiti
extends Activity
implements CustomActivity {
private CustomActivityLogic logic = new CustomActivityLogic();
public void someMethod() { /***/ }
public void myNewMethod() { logic.myNewMethod(this); }
#Override
protected void onCreate(Bundle savedInstanceState) {
logic.onCreate(this, savedInstanceState); // call shared logic
}
public void onCreateSuper(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); // call super
}
}
FragmentActivitii.java
import android.support.v4.app.FragmentActivity;
public class FragmentActivitii
extends FragmentActivity
implements CustomActivity {
private CustomActivityLogic logic = new CustomActivityLogic();
public void someMethod() { /***/ }
public void myNewMethod() { logic.myNewMethod(this); }
#Override
protected void onCreate(Bundle savedInstanceState) {
logic.onCreate(this, savedInstanceState); // call shared logic
}
public void onCreateSuper(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); // call super
}
}
CustomActivityLogic.java
public class CustomActivityLogic {
public void myNewMethod(CustomActivity activity) { /*...*/ }
public void onCreate(CustomActivity activity, Bundle savedInstanceState) {
/* shared creation logic */
activity.onCreateSuper(savedInstanceState); // call-back super
}
}

You wish to add helper methods that help keep track of the orientation. I'd think this is not quite big enough to warrant the creation of a subclass.
Put them in a helper class instead:
public class OrientationHelper {
private Activity activity;
private int current_orientation;
public OrientationHelper(Activity activity){
this.activity = activity;
orientation = Configuration.ORIENTATION_UNDEFINED;
}
public int getNewOrientation() {
return activity.getResources().getConfiguration().orientation;
}
// call this when you wish to update current_orientation
public void updateOrientation() {
current_orientation = getNewOrientation();
}
public int getCurrentOrientation() {
return current_orientation;
}
public boolean isDevicePortrait() {
return current_orientation == Configuration.ORIENTATION_PORTRAIT;
}
public boolean isDeviceLandscape() {
return current_orientation == Configuration.ORIENTATION_LANDSCAPE;
}
public boolean isNewDevicePortrait() {
return getCurrentOrientation() == Configuration.ORIENTATION_PORTRAIT;
}
public boolean isNewDeviceLandscape() {
return getCurrentOrientation() == Configuration.ORIENTATION_LANDSCAPE;
}
public boolean isPortrait2Landscape() {
return isDevicePortrait() && isNewDeviceLandscape();
}
public boolean isLandscape2Portrait() {
return isDeviceLandscape() && isNewDevicePortrait();
}
public String describeCurrentOrientation() {
return describeOrientation(current_orientation);
}
public String describeNewOrientation() {
return describeOrientation(getNewOrientation());
}
private String describeOrientation(int current_orientation) {
switch (current_orientation) {
case Configuration.ORIENTATION_UNDEFINED:
return "ORIENTATION_UNDEFINED";
case Configuration.ORIENTATION_PORTRAIT:
return "ORIENTATION_PORTRAIT";
case Configuration.ORIENTATION_LANDSCAPE:
return "ORIENTATION_LANDSCAPE";
case Configuration.ORIENTATION_SQUARE:
return "ORIENTATION_SQUARE";
default: return null;
}
}
}
In those activities that work with orientation (and only those), you can instantiate the OrientationHelper and call updateOrientation() in select places.
The other bit of code, that organizes the saving of the instance state, I would not put in a different class just so that you can reuse it. Because this is not where one would expect modifications to state saving to occur and therefore it might get overlooked. (It took me a bit of scrolling around to figure out what it's supposed to do.)
I think the most readable way to go about that is to write it out explicitly in each Activity where you use it.
One last thing to consider is that the Sherlock Actionbar already extends Activity. And rightly so, I think. But this means that you'll occasionally run into trouble if you extend Activity too.

How about using the Decorator Pattern? Unfortunately, this will require you to delegate all of the existing methods, or whichever ones are necessary for your purpose.
public class ActivityDecorator extends Activity
{
private Activity RealActivity;
public ActivityDecorator(Activity _realActivity)
{
RealActivity = _realActivity;
}
public void myNewMethod() { ... } // this exposes the added/new functionality
// unfortunately for old functionality you need to delegate
public void oldMethod() { RealActivity.oldMethod(); }
}
However, once you've done this once for the ActivityProxy class, you can construct instances of ActivityDecorator with types that derive Activity such as FragmentActivity in your case. E.g.
ActivityDecorator decorator = new ActivityDecorator(new FragmentActivity());

Your design problem is one of the issues addressed by the upcoming Java 8 virtual extensions. See URL below for more details:
http://java.dzone.com/articles/java-8-virtual-extension
In the meantime, there is no easy way. A decorator class will not work, instead implement a utility class that will be called by both of your classes:
EDITED BASED ON NEW INFO:
/** NOTE: cannot be abstract class **/
public class ActivitiBase {
private int current_orientation = Configuration.ORIENTATION_UNDEFINED; // ORIENTATION_UNDEFINED = 0
private Activity activity;
public void ActivitiBase(Activity activity) {
this.activity = activity;
}
public void onCreate(Bundle savedInstanceState) {
current_orientation = activity.getResources().getConfiguration().orientation;
}
public boolean isDevicePortrait() { return current_orientation ==
Configuration.ORIENTATION_PORTRAIT; }
}
public void myNewMethod() { ... }
}
Activiti class:
public class Activiti extends Activity {
private ActiviBase activitiBase;
public Activiti() {
activitiBase = new ActiviBase(this);
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
activitiBase.onCreate(savedInstanceState);
}
public void myNewMethod() {
activitiBase.myNewMethod();
}
}
FrameActiviti class:
public class FrameActiviti extends FrameActivity {
private ActiviBase activitiBase;
public FrameActiviti() {
activitiBase = new ActiviBase(this);
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
activitiBase.onCreate(savedInstanceState);
}
public void myNewMethod() {
activitiBase.myNewMethod();
}
}