Develop Reference

How can I know that Android SharedPreferences are saved successfully?

I am saving some data to SharedPreference from a fragment and want use these data in other fragments. But I want to perform fragment transaction only if SharedPreferences are saved successfully, otherwise, other fragments would not be able to retrieve data (since using those SharedPreference values to retrieve data).
My code:
public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener{
... ... ... ... ... ... ... ... ...
public void setSharedPref(String key, String val) {
SharedPreferences sharedPref = this.getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString(key, val);
editor.commit();
}
public String fetchSharedPref(String key) {
SharedPreferences sharedPref = this.getPreferences(Context.MODE_PRIVATE);
String val = sharedPref.getString(key, Constant.SHARED_PREF_DEFAULT_MSN);
return val;
}
}
How can I be sure that SharedPreferences are saved successfully?
Is there any way to implement a callback that will be invoked only if SharedPreferences saved successfully?

From the docs.
SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putInt(getString(R.string.saved_high_score), newHighScore);
editor.commit();
Then go and check commit() method here.
Return type: boolean
Description: Returns true if the new values were successfully written to persistent storage.

Find the solution :
SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putInt("Your Key", "Your value");
boolean savedOrNot = editor.commit();
if(savedOrNot){
// Successfully saved
}else{
// Not saved
}

Form Documentation
apply()
This saves your data into memory immediately and saves the data to
disk on a separate thread. So there is no chance of blocking the main
thread (your app won’t hang).
It is the preferred technique but has only been available since
Gingerbread (API 9, Android 2.3).
commit()
Calling this will save the data to the file however, the process is
carried out in the thread that called it, stopping everything else
until the save is complete. It returns true on successful completion,
false on failure.
Use commit() if you need confirmation of the success of saving your
data or if you are developing for pre-Gingerbread devices. commit()
has been available since API 1
so your can check status at editor.commit();
commit() returns true if the save works, false otherwise.

commit() returns true if the save works, false otherwise.
You can alter your method as follows.
public boolean setSharedPref(String key, String val) {
SharedPreferences sharedPref = this.getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString(key, val);
return editor.commit()
}
Difference between apply and commit https://developer.android.com/reference/android/content/SharedPreferences.Editor.html

The editor.commit() will return boolean value , which will let you know if data has been saved.
If you would like to analyze all the data saved in shared preferences and sqlite ,then i would recommend using facebook stetho
Its a debug bridge for android , you can check all of your shared preferences data and sql databases for debugging.

Can't get SharedPreferences with activity

Sorry for my bad English.
On my application, I save token (it's a web app) in shared preferences. In first activity I do this:
(token = 123)
SharedPreferences sp = getPreferences(MODE_PRIVATE);
Editor ed = sp.edit();
ed.putString("token", Main.getToken());
ed.commit();
Log.d("Recieved token: ", sp.getString("token", "null")); // Recieved token: 123
As you see, shared prefs are saved.
I have another activity, which may be called from browser to share link.
Code:
sp = getPreferences(MODE_PRIVATE);
Log.d("Token recieved: ", sp.getString("token", "null")); // null
But on another activity shared prefs return null.
What can I do?

To explain the reason why getPreferences() didn't work for you:
When you call getPreferences() without specifying a Shared Preferences name, it returns a Shared Preference using the calling Activity's class name as the Shared Preference name. That's why you are getting null in your other activity - it's actually a different Shared Preference set that you are referring to.
Use getSharedPreferences instead, using whatever preferences name you like:
getSharedPreferences("my_prefs", Activity.MODE_PRIVATE);
That will then be available throughout your application. However using getPreferences() is suitable where you don't need to refer to the data stored outside of a particular Activity.

use like following,,
SharedPreferences mAppSettings = getSharedPreferences("SharedPref", MODE_PRIVATE);
SharedPreferences.Editor prefEditor = mAppSettings.edit();
prefEditor.putString(""token, "");
prefEditor.commit();
for retrieving,,,
final SharedPreferences mAppSettings1 = getSharedPreferences(
"SharedPref", MODE_PRIVATE);
String token= mAppSettings1.getString("token", "");

Storing data in SharedPreferences accessible to all activities

I want to store and retrieve data that is accessible to all activities in my app using SharedPreferences. Is that possible? Up until now I have been doing it such that the data is stored for a particular activity.

Yes. SharePreferences do exactly this.
In every activity you can this:
SharedPreferences prefs = getSharedPreferences(ApplicationConstants.PREFERENCES, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = prefs.edit();
editor.putString(name, value);
editor.commit();
And then retrieve values in other activty doing this:
mPrefs.getString(name, "");
This is the documentation:
http://developer.android.com/reference/android/content/SharedPreferences.html
And this is a good example to start with:
http://myandroidsolutions.blogspot.it/2012/03/android-preferenceactivity.html

Yes, that's the whole purpose of it.
Here's how you should write to it, via Editor
final SharedPreferences shp = ctx.getSharedPreferences(ctx.getString(R.string.app_name), Context.MODE_PRIVATE);
final SharedPreferences.Editor ed = shp.edit();
ed.putString("var1", "var1");
ed.putString("var2", "var2");
And to load it:
shp.getString("var1", "defvalue");

I have a better version. As sometimes when you try to do getSharedPreferences you might get an error as it could not be found.
This is how I store values in my Android projects.
Add
SharedPreferences sharedPreferences=this.getSharedPreferences("packagename", Context.MODE_PRIVATE);
sharedPreferences.edit().putString("username", "specify name here").apply();
Package Name can be directly copied from top of the activity ex: com.example.name.projectname
Retrieve
String username = sharedPreferences.getString("username","");

If you want to access values in all of your activities I think the better way is storing in a custom Application class and later in activities you can:
((CustomApplication)getApplication()).getStoredValue()
Shared preferences are stored in files and this file access is slower.

Is my example for create function for set and get an object data called "USER"
For set sharePreference data
public void saveUser(User usuario) {
SharedPreferences sharedPref = getSharedPreferences("A", Context.MODE_PRIVATE); // sharedpreference set named "A"
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString("name", usuario.getNombre());
editor.putString("username", usuario.getUsername());
editor.putString("pass", usuario.getContrasena());
editor.putString("roll",usuario.getRol());
editor.commit();
}
For get sharePreference data
public Usuario getUser() {
SharedPreferences sharedPref = getSharedPreferences("A", Context.MODE_PRIVATE); // sharedpreference set named "A"
User usuario = new User();
usuario.setNombre(sharedPref.getString("name", "null"));
usuario.setUsername(sharedPref.getString("username", "null"));
usuario.setContrasena(sharedPref.getString("pass", "null"));
usuario.setRol(sharedPref.getString("roll", "null"));
return usuario;
}
Important: set name to sharePreference in this case "A"

Trouble using sharedPreferences between two activities

I am trying to save a date in one activity and then have that date put in a textView in another activity. I am not sure about how to get the two activities to communicate with each other.
In file called report.java I have this method that gets the date and save it in sharedPrefernces.
private void updateLabel() {
date.setText(fmtDate.format(dateAndTime.getTime()));
SharedPreferences preferences = getPreferences(MODE_PRIVATE);
SharedPreferences.Editor editor = preferences.edit();
editor.putString("date", date.getText().toString()); // value to store
editor.commit();
}
I am trying to figure out how to get my file called inspection use this to populate a textView
The problem I think I am having is with getting the correct name for the report file.
public static final String PREF_FILE_NAME = "report";
SharedPreferences preferences = getSharedPreferences(PREF_FILE_NAME, MODE_PRIVATE);
then I have this code on a method called onResume()
#Override
public void onResume() {
super.onResume();
SharedPreferences preferences = getPreferences(MODE_PRIVATE);
String strDate=preferences.getString("date", date.getText().toString());
date.setText(strDate);
}

You are saving the value to two seperate preference files.
SharedPreferences preferences = getPreferences(MODE_PRIVATE);
SharedPreferences preferences = getSharedPreferences(PREF_FILE_NAME, MODE_PRIVATE);
Use only one.

Why not use the default preference file that is accessible by all classes/activities of your app?
SharedPreferences preference = PreferenceManager.getDefaultSharedPreferences(yourContext);
preferences.edit().putString(YOURKEY, yourStrValue);
This way you are not creating extra preference files in your app that you have to remember which values are stored in which files. Definately makes life easier.

Android - How Do I Set A Preference In Code

I have an Android application in which I have my preferences in an XML file, which works fine. I now want to set one of the preferences using code instead of displaying the entire preference screen, how would I go about doing this?

I assume by preferences you are referring to your application's preferences and not Android phone settings.
To store preferences between runs of you application you need to do the following
Create a SharedPreferences object
SharedPreferences settings = getSharedPreferences(String n, MODE_PRIVATE);
String n identifies your preferences and the second argument is the mode they'll be accessed
Instantiate an Editor object
SharedPreferences.Editor editor = settings.edit();
Note: do not try settings.editor.edit(), this will not make a persistent object and the code below will not work
Write your preferences to the buffer
editor.put...(String, value)
There are numerous put function, putString, putBoolean, etc. The String is the key ("version", "good run") and the value is the value ("1.5.2", true)
Flush the buffer
editor.commit();
This actually writes you put to the preferences. If your app crashes before this line then the preferences will not be written. There is also a documented bug: commit() is supposed to return a boolean indicating success or failure. Last I checked it always returned false.
These preferences will by stored on the phone and will only be accessible to your application.
More documentation is here

I tried this but didn't work:
SharedPreferences settings = getSharedPreferences(String n, MODE_PRIVATE);
Try this instead:
SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);

You can save something in the sharedpreferences by using below code
public static void save(String valueKey, String value) {
SharedPreferences prefs = PreferenceManager
.getDefaultSharedPreferences(context);
SharedPreferences.Editor edit = prefs.edit();
edit.putString(valueKey, value);
edit.commit();
}
To read preferences:
public static String read(String valueKey, String valueDefault) {
SharedPreferences prefs = PreferenceManager
.getDefaultSharedPreferences(context);
return prefs.getString(valueKey, valueDefault);
}