SharedPreferences always get default value in my existing app but when created new app its ok

Question

SharedPreferences doesn\'t work correct in one existing apps. I tried many different ways but still not working. Always get default values app start again.

• It\

Answer 1

Finally I solved that problem. A method was added by one of other developers. All files under data/data/packageName folder except libs folder were being deleted by this method. I think they tried delete cache folder.

Removed this method and it solved.

Answer 2

Just use below method and check.

Create one Java class AppTypeDetails.java

import android.content.Context;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;

public class AppTypeDetails {

    private SharedPreferences sh;

    private AppTypeDetails() {
    }
    private AppTypeDetails(Context mContext) {
        sh = PreferenceManager.getDefaultSharedPreferences(mContext);
    }
    private static AppTypeDetails instance = null;
    public synchronized static AppTypeDetails getInstance(Context mContext) {
        if (instance == null) {
            instance = new AppTypeDetails(mContext);
        }
        return instance;
    }

    // get user status
    public String getUser() {
        return sh.getString("user", "");
    }
    public void setUser(String user) {
        sh.edit().putString("user", user).commit();
    }

    // Clear All Data
    public void clear() {
        sh.edit().clear().commit();
    }
}

Now Set value to SharedPreferences.

AppTypeDetails.getInstance(MainActivity.this).setUser(<user name>);

Get Value form SharedPreferences.

String userName = AppTypeDetails.getInstance(MainActivity.this).getUser();

Now do any thing with the userName.

Always check

if(userName.trim().isEmpty())
{
    // Do anything here.
}

because In SharedPreferences we set user name blank ("")

or

you can set user name null in SharedPreferences then you need check

if(userName != null){
    //do anything here
}

For clear data from SharedPreferences.

AppTypeDetails.getInstance(MainActivity.this).setUser("");

or

AppTypeDetails.getInstance(MainActivity.this).clear();

Answer 3

I recommend controlling your preference check with another preference value.

String user = pref.getString("user", default_user);

In your preference check:

String getStatus = pref.getString("register", "nil");

if (getStatus.equals("true")) {
    // move on code stuff
}
else{
    // ask for preferences
}

In the part where the preference is added.

edit.putString("user", "new_user");
editor.putString("register", "true");
edit.commit;

Answer 4

Your code is right, the code works on any app very well, looks like that in some part of your app the shared preferences are been modified, the only way to find a solution is review all your code, because if this problem only happens on one app, it's somewhere on your app that the shared preferences are been modified, for good practices, you should have only one file class for the management of your preferences on that way you can comment or find usage for a method and you can find where the shared preferences was been modified.

BTW the best way to store an user, password, or any account info is using Account Manager.

For good practices you can see this sample PreferenceHelper class.

public class PreferencesHelper {

public static final String DEFAULT_STRING_VALUE = "default_value";

/**
 * Returns Editor to modify values of SharedPreferences
 * @param context Application context
 * @return editor instance
 */
private static Editor getEditor(Context context){
    return getPreferences(context).edit();
}

/**
 * Returns SharedPreferences object
 * @param context Application context
 * @return shared preferences instance
 */
private static SharedPreferences getPreferences(Context context){
    String name = "YourAppPreferences";
    return context.getSharedPreferences(name,
            Context.MODE_PRIVATE);
}

/**
 * Save a string on SharedPreferences
 * @param tag tag
 * @param value value
 * @param context Application context
 */
public static void putString(String tag, String value, Context context) {
    Editor editor = getEditor(context);
    editor.putString(tag, value);
    editor.commit();
}

/**
 * Get a string value from SharedPreferences
 * @param tag tag
 * @param context Application context
 * @return String value
 */
public static String getString(String tag, Context context) {
    SharedPreferences sharedPreferences = getPreferences(context);
    return sharedPreferences.getString(tag, DEFAULT_STRING_VALUE);
}}

Answer 5

The code itself looks fine and you say it works in other apps. Since you have confirmed the XML file gets properly created, the only remaining option is that something happens to the file before you read it during app launch. If there is no other code in the app that handles any shared preferences, then something must wipe the file during the launch.

You should take careful look at launch configuration of this particular app and compare to other apps where this is working. Maybe there is some option that wipes user data when app is started. I know there is such an option at least for emulator (in Eclipse), but I am not sure if you are running this in emulator or device.

You should also try launching the app directly from the device instead of IDE. This tells if the problem is in the app itself or IDE configuration. And try moving this from onCreate (where I presume this is) to onResume and compare does it work when you resume to the app versus when you completely restart it.