guys,
I've been working on a native Android application for some time and now I am at the end of it there is still a problem I need help with.
My project at github
There is the following problem - when user starts the application for the first time the app will ask him "When does your diet cycle starts?" with a datepicker popup. I am using SharedPreferences to store the result user has picked from the popup. I have separate DatePickerActivity from the MainActivity one that takes care of this datepicker that I start with startActivityForResult(). The DatePickerActivity passes the result to the MainActivity using an Intent.
When I debug the app I see finish() in DatePickerActivity is started twice and the MainActivity is started more than one this cause the datepicker popup to show once again.
Once the start date is set in the system there is no problem with these activities and application works fine.
Then comes the moment when user wants to reset the date - using the basket icon with text like "Изчисти" and the datepicker once again appear twice.
I hope I've been clear enough with my explanation and I am looking fowrard to hearings from you.
Best Regards,
Mihail
I managed to find a work around my problem. I guess I caused it because I need my main layout redraw after user picks a date from the picker and I doing
finish();
startActivity(getIntent());
Here should be the reason for multiple MainActivity instances in the app. Second thing I guest is that committing SharedPreferences to the OS is async and by the time I check for selected date it has not been written yet.
I solved the problem by saving picked date in static instance and when I redraw the main layout I already have the result.
Thank to those who lost some of their time trying to fix my problem!
Related
I have created a simple android quiz app. Where the user takes a quiz and then the app takes them to a result screen where they can see exactly which questions that they got wrong. However at the moment the user can simply go back to the question page (the previous activity) and change their answers what code could I use to prevent this from happening.
Thanks in advance.
If your quiz questions are displayed via one activity, and your results are displayed via another activity, when you call startActivity() to show the results activity, also call finish() to destroy the questions activity.
How would i resume the last viewed activity after the user has been closed the application. It is like, If the user open the application, the first activity will appear and when the user click the button it will proceed to the next activity, if he close the application and open again it will still show the last viewed activity. how would i do that? please help me.
Thank you,
I think you should use sharedpreferences. And in every activity you open, you have to put a value on your sharedpreference so that if you open again your application it will check the value of your shared preference then compare it, call the activity that fits the value you got. Hope it helps :)
You need to track his last activity then, keep it in a database and whenever he returns, look up his last activty in the database...the other way is cookies but not adviseable ....
Place this below line in AndroidManifest.xml for your activities in <activity/>.
android:launchMode="singleTask"
Hello I require some advice on how to approach this problem,
bear with me as I am still new to android.
I have an activity that opens on application start and requires some information from the user, but next time the user opens the app, i want the application to open a different activity that will display the various information.
Kind of like facebooks app, where when you first run it, you have to login, and only then next time you run the app you are guided straight to the feed.
Any ideas how one could do this efficiently?
UPDATE: Ive stored the information via shared preferences and am now using a controller activity that decides which step to take.
So, Controller activity runs on start up, and decides whether to show a log in screen or whether to go straight to the information. But now im encountering a problem where i end up opening a blank activity (the controller) and then another ontop of that ( the decided activtiy). I dont want the blank activity to show, so its kinda of like a background process, any ideas?
Ideally you would have a main activity like a controller. Use a SharedPreference object to keep track of whether the user is logged in or not. So back in your main activity, read this value and if it is set go to your news feed activity else show a login screen activity. (as you do the check and redirection, you can show a progress dialog)
links for SharedPreferences
MobTuts
Android Developer
While searching this question I have seen this. One time Android setup screen?
It asks my question, but I can never get it to work. What I want to happen is when I first startup the app, it gives me the setup screen. Then when I press save, I want it to quit the app. When I click the app again, I want it to preform a task, rather than show up with a screen. So thats really 2 questions, how to make it show a setup screen one time, and then how to make it do an action(by clicking on the app) without a screen showing up at all.
Right now, I use SharedPreferences editor to input my settings.
Pretty simple, in the onCreate of your activity:
savedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
if(savedPreferences.getBoolean(PREF_SHOW_ABOUT_ON_APP_START, true)){
Intent intent = new Intent(this, SetupActivity.class);
startActivity(intent);
savedPreferences.edit().putBoolean(PREF_SHOW_ABOUT_ON_APP_START, false).commit(); // YOu could do this line within the SetupActivity to ensure they have actually done what you wanted
finish();
} else {
// Go somewere else
}
You don't have to activity switch, but you get the picture
For the first time only set up screen, you simply have to use SharedPreferences. Check if a value, alreadyLaunched exists in the shared preferences. If not, show the set up screen. If yes show your app.
For the second part of your question, it would be considered very bad practice to have an icon app that does nothing at all when you click it. How would the user know that it worked or did what it was supposed to do ?
For the "I want a task to execute but I don't want the user to see it happening", I believe you should look at services. When your user closes the app clicking the save button on the set up screen, start a service ( http://developer.android.com/reference/android/app/Service.html )
When the user clicks again on your app, simply show a message and make the app call the service via an intent.
Probably you are forgetting to call
myEditor.commit()
after you are done with setting your preferences.
I understand how to save an application's state by using SharedPreferences, onSavedInstanceState() & onRestoreInstanceState(), etc as outlined in a similar post ( Saving Android Activity state using Save Instance State ), but how do I save the last activity?
To be more specific, my application starts up and goes to a login screen. Once a user logs in and navigates through several activities, lets say he or she leaves the app using the home button or in some other way. Next time the user starts the app, it will go back to the login screen and do a login again. Instead, I want the app to start up and go to the last activity that was on top of the stack when the user left the app in the previous session.
How is the last activity saved so that it can be restored on app startup?
I believe Android does this automatically. We have an app that we are working on. When I click the home button and them come back to the app, it starts in the activity where I left off. We have not written any code to make this happen. It just seems to work.
My colleague has written an article on Android application state including details on getLastNonConfigurationInstance() which retrieves the instance that was last stored. Take a look here: http://www.eigo.co.uk/Managing-State-in-an-Android-Activity.aspx
Please note that the above answer is correct only on one case: If your process does not get killed by android because the resources (memory, ...) are needed for a different reason.
To get what you describe, I would write a custom parent activity and override the correct life-cycle methods to store your application state and read it and act accordingly. Then let all your activities inherit from MyActivity (instead of android.app.Activity)
public MyActivity extends android.app.Activity {
...
#Override
public onCreate(...) {
// Read the Application state,
// check if the currently launching Activity is the right one,
// if not, start the last Activity and finish the current one.
}
#Override
public onDestroy(...) {
// Store the current Activity ID in the SharedPreferences
}
...
}
Take care to call the super.onDestroy and super.onCreate methods in all your Activites (like you should do anyways).
Happy coding and have fun with Android!