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A variable is reset after some time

There's an int variable accessed via singleton pattern.
But the problem is that the variable is set once and it's reset to 0 after some time.
It seems to be reset by garbage collection. Saving the value in Activity.onSaveInstanceState and restoring it in onCreate() is non-working.
Is the solution to save the variable in disk?
I just want to prevent it from resetting.

The variable will only stay active as long as the application is active. Android is notorious for killing background processes automatically. Unfortunately, if you're trying to access a variable that you'd like to persist over multiple runs of the application, you will need to write it to disk somehow.
There are a couple of options open to you, however. I will list the ones Google recommends.
Shared Preferences, "Store private primitive data in key-value pairs."
Internal Storage, "Store private data on the device memory."
External Storage, "Store public data on the shared external storage."
SQLite Database, "Store structured data in a private database."
Network Connection, "Store data on the web with your own network server."
Of all of these solutions, Shared Preferences, is probably the easiest to implement. It is as simple as:
public class Calc extends Activity {
public static final String PREFS_NAME = "MyPrefsFile";
#Override
protected void onCreate(Bundle state){
super.onCreate(state);
. . .
// Restore preferences
SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
boolean silent = settings.getBoolean("silentMode", false);
setSilent(silent);
}
#Override
protected void onStop(){
super.onStop();
// We need an Editor object to make preference changes.
// All objects are from android.context.Context
SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean("silentMode", mSilentMode);
// Commit the edits!
editor.commit();
}
}
Code is from the Android Data Storage page.

I just want to prevent it from resetting.
You can use the SharedPreferences to save and then retrieve the variable later. A tutorial on how to do so can be found here.
On a side note though, are you sure your variable is resetting because of garbage collection?

Save app when user exits using back button [closed]

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I know that when the user presses back button the saveoninstance is not supposed to be called.
I have a layout with many edittexts added dynamically by user, and then the user can enter text. I managed to save these when the user rotates screen using saveoninstance etc.
However, I also want to save these when the user exits app using the back button so when the app is opened again a "continue" button should be available for the user to continue (meaning adding all the text boxes again). I kind of know how to save and retrieve them, but which method should I use? Should i write a file for a example? Thanks.

When the user pressed back button application is closed. When he open app again it start as new instance and don't remember what user done before.
If u have to save data, then u can save them (eg. to Preferences or database) in onPasue or onDestroy

If you know how to save and retrieve them, why dont you just override the Back button and write save functionality there.
e.g.
public boolean onKey(View v, int keyCode, KeyEvent event)
{
// TODO Auto-generated method stub
return false;
}
#Override
public void onBackPressed()
{
/*Your functione here to what should be done on Back Button Press event*/
}

What you have to do is, you have override the below method in your Activity,
#Override
public void onBackPressed() {
// TODO Auto-generated method stub
super.onBackPressed();
}
And save the state of your activity in SharedPrefrence, and next time when you enter your Activity get the value from the Sharedpreference and set the state accordingly.
Example,
private void SavePreferences(){
SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putBoolean("state", "true");
editor.commit();
}
private void LoadPreferences(){
SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
Boolean state = sharedPreferences.getBoolean("state", false);
button.setEnabled(state);
}
#Override
public void onBackPressed() {
SavePreferences();
super.onBackPressed();
}
onCreate(Bundle savedInstanceState)
{
//just a rough sketch of where you should load the data
LoadPreferences();
}

Basically shared preference in android are used to save the state of an activity or to save the important data within the scope of an application means data will remain saved till the application is installed in the devices. Shared Preference also works as Sessions which are used for the automatic login process.
see this Documentation.
And here is an Example.

Well its pretty simple. All you need to do is:
Use shared preferences and bundle.
Save everything in the onSavedInstanceState(Bundle outState)
Now how you do is:
Overwrite the function onSavedInstanceStae(Bundle outState)
and inside it
Save everything in Shared Preferences and then bundle them ,and this bundle is then sent automatically as a parameter in your onCreate(Bundle bundle)
Thus in your onCreate check if the bundle==null; if not retrieve sharedPreferences and load the data just like you saved it.

How to show different page if user is first time user (Android)

I have a blank-ish Android Project and what I want to do is take the user to a different "page/screen" if it is their first time only.
I know the logic for this but since I'm new to Android, I'm unsure of how to code this.
Below are the steps I believe I need to take in order to accomplish this:
App loads. If Local storage contains setting "FirstTimeUser", then it is not their first time using the app. Show the MainActivity page. If FirstTimeUser setting does not exist, it is their first time using the app (or they have uninstalled and reinstalled it), so instead, show WelcomeActivity page.
After viewing Welcome activity page, create FirstTimeUser setting and set to False.
But how do I code this for an Android app?

Use shared preferences as shown:
//declare as global
SharedPreferences prefs = null;
//and in your onCreate method:
prefs = getSharedPreferences("packageNameHere", MODE_PRIVATE);
if (prefs.getBoolean("firstrun", true)) {
//do stuff here if first run
//make sure to flag the boolean as false
prefs.edit().putBoolean("firstrun", false).commit();
}
else{
//if not first run, do something else
}

There is something called "SharedPreferences" that i believe your looking for.
http://developer.android.com/reference/android/content/SharedPreferences.Editor.html

Android save details screen

I am working on a small project that requires a details screen where the user inputs his details and they are permanently stored. The user must have the option to change the details as well if he needs to do so. I looked into the saved preferences library however it does not seem to offer such functionality.
To give a visual idea of what is required, something like this screen should be fine:
http://www.google.com.mt/imgres?start=97&num=10&hl=en&tbo=d&biw=1366&bih=643&tbm=isch&tbnid=aQSZz782gIfOeM:&imgrefurl=http://andrejusb.blogspot.com/2011/10/iphone-web-application-development-with.html&docid=YpPF3-T8zLGOAM&imgurl=http://2.bp.blogspot.com/-YRISJXXajD0/Tq2KTpcqWiI/AAAAAAAAFiE/-aJen8IuVRM/s1600/7.png&w=365&h=712&ei=rbX6ULTDCOfV4gTroIDoCg&zoom=1&iact=hc&vpx=834&vpy=218&dur=2075&hovh=314&hovw=161&tx=80&ty=216&sig=108811856681773622351&page=4&tbnh=155&tbnw=79&ndsp=35&ved=1t:429,r:4,s:100,i:16
Any help is much appreciated. Thanks in advance

You could easily use Shared Preferences to store user's details. Everytime the Preference screen is opened the stored data can then be extracted from the Shared Preferences and presented to the user for edit. ONce the edit is done the new data can be updated back in the the Shared Preferences.
Also look at this thread to see how this can be done.

Using SharedPreferences would be perfect for this kind of small amount of data which you want to store persistently.
// 'this' is simply your Application Context, so you can access this nearly anywhere
SharedPreferences prefs = this.getSharedPreferences(
"com.example.app", Context.MODE_PRIVATE);
To obtain from the preferences:
// You can equally use KEY_LAST_NAME to get the last name, etc. They are just key/value pairs
// Note that the 2nd arg is simply the default value if there is no key/value mapping
String firstName = prefs.getString(KEY_FIRST_NAME_CONSTANT, "");
Or to save:
Editor editor = prefs.edit();
// firstName being the text they entered in the EditText
editor.putString(KEY_FIRST_NAME_CONSTANT, firstName);
editor.commit();

You can achieve such functionality using SharedPreferences Class in android.
public void onCreate(Bundle object){
super.onCreate(object);
// Initialize UI and link xml data to java view objects
......
SharedPreferences myPref = getPreferences(MODE_PRIVATE);
nameView.setText(myPref.getString("USER_NAME", null));
passView.setText(myPref.getString("PASSWORD", null));
}
public void onStop(){
super.onStop();
if (isFinishing()) {
getPreferences(MODE_PRIVATE).edit()
.putString("USER_NAME", nameView.getText().toString())
.putString("PASSWORD", passView.getText().toString())
.commit()
}
}

Detect First Run

I am trying to detect if my app has been run before, by using this code:
(This is in my default Android activity)
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState == null) {
Log.w("activity", "first time");
setContentView(R.layout.activity_clean_weather);
} else {
Log.w("activity", "second time");
setContentView(R.layout.activity_clean_weather);
}
}
When I first run the app it says first time, when I run it a second time, first time, and a third, first time....
I am using an actual Android device and I am not using the run button each time. I run the app once with the Eclipse run button, then I close the app and press on its icon on my phone.
Is there something wrong with my code?

savedInstanceState is more for switching between states, like pausing/resuming, that kind of thing. It must always be created by you, also.
What you want in this case is SharedPreferences.
Something like this:
public static final String PREFS_NAME = "MyPrefsFile"; // Name of prefs file; don't change this after it's saved something
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0); // Get preferences file (0 = no option flags set)
boolean firstRun = settings.getBoolean("firstRun", true); // Is it first run? If not specified, use "true"
if (firstRun) {
Log.w("activity", "first time");
setContentView(R.layout.activity_clean_weather);
SharedPreferences.Editor editor = settings.edit(); // Open the editor for our settings
editor.putBoolean("firstRun", false); // It is no longer the first run
editor.commit(); // Save all changed settings
} else {
Log.w("activity", "second time");
setContentView(R.layout.activity_clean_weather);
}
}
I basically took this code directly from the documentation for Storage Options and applied it to your situation. It's a good concept to learn early.

You may use a self-defined shared preference to archive your goal.

The fact is that savedInstanceState holds persistent data across activities. As such if you restart the app, savedInstanceState will be null across runs. You should either use a Preference or some data base entry to keep track of your first run. I myself use a SharedPreference for this purpose.

savedInstanceState will be null if the app is not already loaded in memory. If you want to detect whether the app has run for the very first time, you have to apply different technique, such as using sharedPrefs / DB to store a property for the first run.
i.e. Check sharedPrefs for property "firstRun"
if exists, then it is not a first run
else it is the first run
set the firstRun property to true