SharedPreferences Long value

Question

Here I'm creating a SharedPreferences if I'm not wrong i'm using this code :

SharedPreferences sp = getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sp.edit();
editor.putLong("ExactTime", minutesToMilliseconds(NumberPicker2.getValue()));
editor.commit();

What I'm doing is I get a value from a NumberPicker and I want to save this value and once an user restart the APP or even reboot the device (I don't know if SharedPreferences does it...) when the user opens the APP it still the same number picked from NumberPicker.

And I want to use this in a class that extends a Service. What I've tried is :

SharedPreferences sp = this.getSharedPreferences("ExactTime", Context.MODE_PRIVATE);
WifiTimeSearch = sp.getLong("ExactTime", 0);

Here is where I'm lost... I've read that this "0" means a default value but I want to use the same value that I've stored on SharedPreferences... And when I try to use this Long value, the value is "0".

What I'm doing wrong?

Answer 1

You're reading and writing to different SharedPreference files.

Also, by using getPreferences(), you're writing to SharedPreferences that are local to that Activity.

From the source code:

/**
     * Retrieve a {@link SharedPreferences} object for accessing preferences
     * that are private to this activity.  This simply calls the underlying
     * {@link #getSharedPreferences(String, int)} method by passing in this activity's
     * class name as the preferences name.
     *
     * @param mode Operating mode.  Use {@link #MODE_PRIVATE} for the default
     *             operation, {@link #MODE_WORLD_READABLE} and
     *             {@link #MODE_WORLD_WRITEABLE} to control permissions.
     *
     * @return Returns the single SharedPreferences instance that can be used
     *         to retrieve and modify the preference values.
     */
    public SharedPreferences getPreferences(int mode) {
        return getSharedPreferences(getLocalClassName(), mode);
    }

To make it work, just use the default SharedPreferences for your app:

Writing:

    SharedPreferences sp =  PreferenceManager.getDefaultSharedPreferences(this);
    SharedPreferences.Editor editor = sp.edit();
    editor.putLong("ExactTime", minutesToMilliseconds(NumberPicker2.getValue()));
    editor.commit();

Reading:

    SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
    WifiTimeSearch = sp.getLong("ExactTime", 0);

Note that as long as you are in an Activity or a Service, you can use this as the Context.

Answer 2

In SharedPreferences, The first parameter is the key and the second parameter is the MODE. So to COMMIT as well as to retrieve value we have to use same key.

try this code to commit :

SharedPreferences sp = getSharedPreferences("ExactTime",Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sp.edit();
editor.putLong("ExactTime", minutesToMilliseconds(NumberPicker2.getValue()));
editor.commit();

Answer 3

I guess problem is you are passing preference file name as "ExactTime" while reading from preferences, while saving you are not specifying any

Try this

SharedPreferences sp = getSharedPreferences(null,Context.MODE_PRIVATE);
WifiTimeSearch = sp.getLong("ExactTime", 0);