CODEWITHSUNDEEP
androidsharedpreferences
Marley
Marley

Reputation: 185

Android Preferences onBackButton

i'm saving the users login information to SharedPreferences, so he only has to configure his login data once.

This is my onBackPressed method in my Preferences.class (extends PreferenceActivity):

    @Override
public void onBackPressed() {
    //Login again
    Intent intent = new Intent(Preferences.this, LoginActivity.class);
    startActivity(intent);
}

What I need is a if-condition which checks, if the preferences changed or not.:

If the user opens the Preferences Activity (edit: from any View(!)), and does not change anything and clicks the backbutton -> just go back to last state.

If the preferences changed: call LoginActivity.

Couldnt find a solution yet and the LoginActivity gets called whenever i hit the backbutton.

Thanks in advance, Marley

Upvotes: 0

Views: 153

Answers (2)

Emil Adz
Emil Adz

Reputation: 41099

To determine if there was a change in SharedPreferences you have to assign a OnSharedPreferenceChangeListener to your SharedPreferences object like this:

prefs = PreferenceManager.getDefaultSharedPreferences(this);
prefs.registerOnSharedPreferenceChangeListener(this);

in this case I'm doing it in my Application class that's implementing:

public class YambaAppObj extends Application implements OnSharedPreferenceChangeListener

Then you will have to override:

public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key)
{
    //this method will be called when preferences are changed.
    //do here what you want to record the change
    Log.d(TAG , "onSharedPreferenceChanged for:" + key);
}

and then you could check this record in your onBackPressed() method of your Preferences Activity and act accordingly.

Upvotes: 1

Marcin Orlowski
Marcin Orlowski

Reputation: 75629

You can use OnSharedPreferenceChangeListener or (depending on what you really meany by changed) you can try utilising onSharedPreferenceChanged() like:

protected Boolean mPrefsChanged = false;

@Override
public void onSharedPreferenceChanged( SharedPreferences sharedPreferences,
                                                                  String key ) {
    mPrefsChanged = true;
}

of course it's far from perfect, but at least you got more options

Upvotes: 1

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