CODEWITHSUNDEEP
androidandroid-activitysharedpreferencespreferenceactivityonresume
akrog
akrog

Reputation: 326

React in the Android main activity upon a preference change in the PreferenceActivity

I want to update main activity view when returning from the PreferenceActivity. I have read many threads about this and have implemented different approaches, but there is no way ...

Approach 1: Using startActivityForResult()

public boolean onOptionsItemSelected( MenuItem item ) {
    switch( item.getItemId() ) {
        case R.id.about:
            AboutDialog about = new AboutDialog(this);
            about.setTitle(getString(R.string.About));
            about.show();
            break;
        case R.id.menu_settings:
            startActivityForResult(new Intent(MainActivity.this, SettingsActivity.class),-1);
            break;
        default:
            return super.onOptionsItemSelected(item);
    }
    return true;
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    this.charts.redraw();
    super.onActivityResult(requestCode, resultCode, data);
}

onActivityResult() is never called. I have also tried using a valid requestCode but the result is the same.

Approach 2: Using OnSharedPreferenceChangeListener

public class MainActivity extends Activity implements OnItemSelectedListener, View.OnClickListener, OnCheckedChangeListener, OnSharedPreferenceChangeListener {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        // ...
        PreferenceManager.getDefaultSharedPreferences(this).registerOnSharedPreferenceChangeListener(this);
    }

    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        this.charts.redraw();
    }

But again onSharedPreferenceChanged() is never called. I think it is not because of the well-known garbage collector issue since my listener is the MainActivity object and not a temporary object.

Approach 3: Using onResume()

public class MainActivity extends Activity implements OnItemSelectedListener, View.OnClickListener, OnCheckedChangeListener, OnSharedPreferenceChangeListener {

    @Override
    protected void onResume() {
        this.charts.redraw();
        super.onResume();
    };

But again onResume() is not called as expected, indeed it is called when the PreferenceActivity is just started!!!??

Finally, the PreferenceActivity:

@SuppressWarnings("deprecation")
public class SettingsActivity extends PreferenceActivity implements OnSharedPreferenceChangeListener {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.preferences);
        initSummaries(this.getPreferenceScreen());
    }

    private void initSummaries( PreferenceGroup pg ) {
        for( int i = 0; i < pg.getPreferenceCount(); i++ ) {
            Preference p = pg.getPreference(i);
            if( p instanceof PreferenceGroup )
                initSummaries((PreferenceGroup)p);
            else
                setSummary(p);
        }
    }

    private void setSummary(Preference pref) {
        if( pref instanceof ListPreference ) {
            ListPreference listPref = (ListPreference)pref;
            pref.setSummary(listPref.getEntry());
        }
    }

    public void onSharedPreferenceChanged(SharedPreferences sp, String key) {
        Preference pref = findPreference(key);
        setSummary(pref);
    }

    @Override
    protected void onResume() {
        super.onResume();
        getPreferenceScreen().getSharedPreferences()
                .registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    protected void onPause() {
        super.onPause();
        getPreferenceScreen().getSharedPreferences()
                .unregisterOnSharedPreferenceChangeListener(this);
    }
}

If I restart the application, the new values are displayed, so they are stored in the shared preferences correctly.

Am I missing something? This is quite frustrating ...

Upvotes: 2

Views: 822

Answers (1)

M Rajoy
M Rajoy

Reputation: 4094

You don't seem to be calling setResult on your PreferencesActivity.

Upvotes: 1

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