I've looked all over and can't seem to find an answer to my issue. For some reason the data saved in SharedPreferences reappears after switching activities. Why is my SharedPreferences still the exact same as it was before I cleared it and how can I fix this?
In first activity:
#Override
protected void onStop() {
super.onStop();
SharedPreferences sp = this.getSharedPreferences(TEMP_KEY, MODE_PRIVATE);
Gson gson = new Gson();
String objectJson = gson.toJson(object, Object.class);
String activityJson = "FirstActivity";
SharedPreferences.Editor editor = sp.edit();
editor.putString(CONTINUE_KEY, objectJson);
editor.putString(ACTIVITY_KEY, activityJson);
editor.apply();
}
public void onClickSave() {
Gson gson = new Gson();
String objectJson = gson.toJson(object);
SharedPreferences sp getSharedPreferences(SAVE_KEY, MODE_PRIVATE);
SharedPreferences.Editor editor = sp.edit();
editor.putString(object.getDate(), objectJson);
editor.apply();
SharedPreferences spTemp = this.getSharedPreferences(TEMP_KEY, MODE_PRIVATE);
spTemp.edit().clear().apply();
// go back to the main menu
Intent intent = new Intent(this, MainActivity.class);
startActivity(intent);
}
Before the apply():
After the apply():
In Main Activity:
SharedPreferences sp = this.getSharedPreferences(TEMP_KEY, MODE_PRIVATE);
From main activity:
From Coordinating activities android documentation.
When one activity starts another, they both experience lifecycle
transitions. The first activity stops operating and enters the Paused
or Stopped state, while the other activity is created. In case these
activities share data saved to disc or elsewhere, it's important to
understand that the first activity is not completely stopped before
the second one is created. Rather, the process of starting the second
one overlaps with the process of stopping the first one.
The order of lifecycle callbacks is well defined, particularly when
the two activities are in the same process (app) and one is starting
the other. Here's the order of operations that occur when Activity A
starts Activity B:
Activity A's onPause() method executes.
Activity B's onCreate(), onStart(), and onResume() methods execute in sequence. (Activity B now has user focus.)
Then, if Activity A is no longer visible on screen, its onStop() method executes.
This predictable sequence of lifecycle callbacks allows you to manage
the transition of information from one activity to another.
Back to your case, when you start MainActivity from FirstActivity.
FirstActivity's onPause() method executes.
MainActivity's onCreate(), onStart(), and onResume() methods execute in sequence. (MainActivity now has user focus.)
Then, if FirstActivity is no longer visible on screen, its onStop() method executes.
When the code in onClickSave executes.
SharedPreferences spTemp = this.getSharedPreferences(TEMP_KEY, MODE_PRIVATE);
spTemp.edit().clear().apply();
At this time, TEMP_KEY prefs has been cleared. After MainActivity is visible on screen, FirstActivity will be no longer visible on screen, so its onStop() method executes.
SharedPreferences sp = this.getSharedPreferences(TEMP_KEY, MODE_PRIVATE);
Gson gson = new Gson();
String objectJson = gson.toJson(object, Object.class);
String activityJson = "FirstActivity";
SharedPreferences.Editor editor = sp.edit();
editor.putString(CONTINUE_KEY, objectJson);
editor.putString(ACTIVITY_KEY, activityJson);
editor.apply();
In this code you add two entries into TEMP_KEY prefs again. So when users click on a button in MainActivity, at that time the prefs size is 2 instead of 0 as you expected.
Why is my SharedPreferences still the exact same as it was before I
cleared it?
This is predictable or expected behavior in Android. You can put a log in onCreate(), onStart(), onResume() method of MainActivity, then you can see TEMP_KEY prefs size at that time is always 0.
How can I fix this?
Do not add new entries into TEMP_KEY in onStop(), you should add in onPause() instead.
Save To Shared Preferences
SharedPreferences sp = getSharedPreferences("test" , MODE_PRIVATE);
SharedPreferences.Editor spEditor = sp.edit();
spEditor.putString("hello1" , "hello11");
spEditor.putString("hello2" , "hello22");
spEditor.apply();
Clear From Shared Preferences
SharedPreferences sp1 = getSharedPreferences("test" , MODE_PRIVATE);
SharedPreferences.Editor spEditor1 = sp1.edit();
spEditor1.clear();
spEditor1.apply();
Get From Shared Preferences
SharedPreferences sp2 = getSharedPreferences("test" , MODE_PRIVATE);
String value = sp2.getString("hello1" ,"noting");
Log.i("test_sp" , " == == ==" +value);
First, you have different preference file name for getSharedPreferences(String name, int mode), in onStop() and onClickSave() methods:
// in onStop()
SharedPreferences sp = this.getSharedPreferences(TEMP_KEY, MODE_PRIVATE);
// in onClickSave()
SharedPreferences sp getSharedPreferences(SAVE_KEY, MODE_PRIVATE);
you need to use the same file name to access the same preference.
Second, onStop() is not always guaranteed to be called, so it's not a reliable method to save your preferences. Related answer: Is onStop() always preceded by onPause()
Third, always save the preference when you need to keep the value in it. Don't wait to save it later and hoping that you can depend on either onPause(), onStop(), or onDestroy(). Never assume that your application will gracely terminate by user or system.
I'm new to Java/Android programming. I'm getting to know how the layout works and how to redirect it. I've got a splash screen > login > main . Now I want to skip the login activity. How can I do it ?
Edit:
This is what my code looks like now, after answer:
SharedPreferences prefs = getSharedPreferences("myPref", 0);
SharedPreferences.Editor editor = prefs.edit();
editor.putBoolean("Bool", true);
editor.commit();
How I check from my Splashscreen:
SharedPreferences prefs = getSharedPreferences("myPref", 0);
if (prefs.getBoolean("Bool", false)) { //login_activity; }
else{ //maint_activity;
I think this would work.
You can use SharedPreferences to store some boolean value like skipLogin. During splash screen you can check this value, and display login or main, depending on result.
Simple logic, during the splash screen run the following method:
if(login){
redirects to main
}
else{
redirects to login
}
So I am trying to use SharedPreferences to pass a value from the Activity to a Class. The problem is the following:
On initial loading of the Activity, the value is stored in SharedPreferences but if I exit the Activity and return back, and try to update the value, the SharedPreferences does not seem to update and stays at the value of the initial load of the Activity.
Some class function
private void populatePlayerQueue(){
int category_index;
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this.getContext());
category_index = sharedPreferences.getInt("selected_category", 0);
}
Activity onResume
#Override
public void onResume() {
super.onResume();
int tmp = Integer.parseInt(getIntent().getStringExtra("CategoryIndex"));
//store the category in the shared preferences
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putInt("selected_category", tmp);
editor.commit();
}
What I am trying to do:
I have to send an integer from the activity to a specific class and if I come back to the activity then I need to store the update value and so the class will be able to access the newly updated value again. I only have access to the context and not the activity. This causes errors if I try to create an interface callback to communicate with the activity. So this option is eliminated, hence I am trying anything I can to do that.
For some better result remove the SharedPreference through its key at the time of exit application.
In your case when you exit your application just clear the SharedPreference like:
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.remove("selected_category"); //Just remove it by its specific key
editor.commit();
Then it will clearly load and save the new value again when you go back to your application on the same key or you can use new one.
I have developed an App where the user has to login into the app using the login Activity. After successful login, the app is directed to Activity B. The app doesn't provide any signout options.So next time when the user uses the app I want to hide the login Activity's layout. Is it possible to do so?If yes, how is it possible?
In LoginActivity do as Suggested by nr4bt but instead of int Put & get Boolean Value in SharedPreference.
write this code
SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();
editor.putValue("loginStatus", true);
editor.commit();
& onCreate() of LoginActivity Write this code
SharedPreferences prefs = getPreferences(MODE_PRIVATE);
String restoredText = prefs.getBoolean("loginStatus", false);
if (restoredText == true) {
// start activity
finish(); // destroy login so user can't come back with back button
}
Hope this helps you.
Keep a variable in sharedpreferences and check it when your login activity starts
in LoginActivity, when the user press login button and if success,
SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();
editor.putInt("loginStatus", 1);// removed ""
editor.commit();
Then in onCreate check the variable,
SharedPreferences prefs = getPreferences(MODE_PRIVATE);
int restoredText = prefs.getInt("loginStatus", 0);
if (restoredText == 1) {
// start activity
finish(); // destroy login so user can't come back with back button
}
It is quite simple to achive with SharedPreferences. You just save that user has loged in and later on start check if he already done it or not and act properly.
How can I reload SharedPreferences when I resume from one activity to another? If I resume, it is possible that user has changed the settings. Is it possible to reload SharedPreferences or do I need to refresh/reload activity. And if, then how?
There is no difference in how you get and set SharedPreferences normally and from doing so in onResume. What you will need to do in addition to getting the most recent preferences, is update any objects you have in the Activity that use preference values. This will ensure your Activity is working with the most recent values.
A simple example:
protected void onResume() {
super.onResume();
getPrefs();
//...Now update your objects with preference values
}
private void getPrefs() {
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
String myPref = prefs.getString("myPref", "");
}