I have an android main activity showing some data which are taken from the database. Now I have a PreferenceActivity which is shown when the user wants to change some preference, or delete the content of the database. But if this is the case, how do I force a 'reload' or something of the main activity from a class outside the main activity?
Set a OnSharedPreferenceChangeListener listener in your MainActivity to automatically detect any changes in the preferences.
SharedPreferencesListener
MainActivity.java
public class MainActivity extends ... {
private SharedPreferences settings;
private SharedPreferences.OnSharedPreferenceChangeListener listener;
...
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
settings = PreferenceManager.getDefaultSharedPreferences(this);
listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
#Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
// Refresh display
refreshDisplay();
}
};
// Register the listener on the SharedPreferences
settings.registerOnSharedPreferenceChangeListener(listener);
// Other code
}
public void refreshDisplay() {
// Retrieve entries from sharedPreferences & display them, e.g
String prefValue1 = settings.getString("key1", "default value 1");
String prefValue2 = settings.getString("key2", "default value 2");
// Update UI with these values
}
}
EDIT:
Here is how your PreferenceActivity should be:
public class SettingsActivity extends PreferenceActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// R.xml.settings refers to the XML layout file named "settings"
// in your res/xml directory
addPreferencesFromResource(R.xml.settings);
}
}
If you just want to recharge an activity, you can do something like this:
finish();
startActivity(getIntent());
Related
Hi for me one doubt if I change any content or color of activity example, in activity1 I have one textview with data "apple" from shared preference. And I am clicking a button to start new activity2 there I am clicking one button to update the shared preference "apple" to "gova" I click back button of activity2 textview in activity should update. Is there any way to update without onResume() method or explain how onResume() working...?
onResume() is called every time your activity is shown to the user. Thus, if the user goes to another activity and then comes back to the first one, onResume() will be called. Your code should look like:
#Override
protected void onResume() {
super.onResume();
myTextView.setText(preferences.getString("myKey", "defaultValue");
}
If, for any reason, you'd prefer not to use onResume(), you can register a OnSharedPreferenceChangeListener, which will be called every time a shared pref value is changed.
Your first activity will include code that looks like this:
public class MainActivity extends AppCompatActivity {
SharedPreferences preferences;
SharedPreferences.OnSharedPreferenceChangeListener listener;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_layout);
preferences = PreferenceManager.getDefaultSharedPreferences(this);
listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
#Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
if (key.equals("myKey")) {
// update your textview
}
}
};
preferences.registerOnSharedPreferenceChangeListener(listener);
}
#Override
protected void onDestroy() {
super.onDestroy();
preferences.unregisterOnSharedPreferenceChangeListener(listener);
}
}
Just override onBackPressed method in second activity and in it set the value to shared preferences :
#Override
public void onBackPressed() {
// Set shared preference value
}
You should ideally use onBackPressed instead on onResume. Below is a code snippet on similar lines that should help
#Override
public void onBackPressed() {
new AlertDialog.Builder(this)
.setTitle("Really go back?")
.setMessage("Are you sure you want to?")
.setNegativeButton(android.R.string.no, null)
.setPositiveButton(android.R.string.yes, new OnClickListener() {
public void onClick(DialogInterface arg0, int arg1) {
Activity1.super.onBackPressed();
//change sharedPreferences here
}
}).create().show();
}
Hope this helps
public class SettingsActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_settings);
getFragmentManager().beginTransaction()
.add(R.id.settingsContainer, new SettingsFragment())
.commit();
}
public static class SettingsFragment extends PreferenceFragment implements SharedPreferences.OnSharedPreferenceChangeListener {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.preferences);
}
#Override
public void onResume() {
super.onResume();
getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
}
#Override
public void onPause() {
super.onPause();
getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
}
#Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
if (key.equals("aKey") {
Preference pref = findPreference(key);
pref.setSummary(sharedPreferences.getString(key, ""));
}
}
}
}
When the user changes his preferences they are stored and showed by the listener.
When the activity is restarted I lost all the summaries, but values are correctly stored because they are retrieved if I click on each preference.
I'd like to show what was done before, not default values.
In your onResume() method after registering the listener just call the listener with every preference key.
#Override
public void onResume() {
super.onResume();
getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
onSharedPreferenceChanged(getPreferenceScreen().getSharedPreferences(), "your_key");
}
when the Fragment was created, you call the following method:
addPreferencesFromResource(R.xml.preferences)
the if the xml file preferences content is stationary, and you change another preference file when accept onSharedPreferenceChanged.
May you can get values with method getActivity().getSharedPreferences().
I have preference xml and following code:
public class MainActivity extends PreferenceActivity implements SharedPreferences.OnSharedPreferenceChangeListener
{
#SuppressWarnings("deprecation")
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.preferences);
}
#Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
Toast.makeText(getApplicationContext(), "DO SOMETHING", Toast.LENGTH_LONG).show();
}
}
I want to get notified over toast message, when one or more preferences are changed. I think upper code should work, but for some reason it doesn't.
I have for example CheckBoxPreference in my xml file. And when I check or uncheck CheckBox I want to be notified.
You have to set the listener like this for example:
PreferenceManager.getDefaultSharedPreferences(this).
registerOnSharedPreferenceChangeListener(this);
or, if You don´t use the default shared preferences, You have to get Your prefs and then register them:
SharedPreferences preferences = getSharedPreferences("your_shared_prefs", Context.MODE_PRIVATE);
preferences.registerOnSharedPreferenceChangeListener(this);
You should register to listen to the shared preference changes:
#Override
public void onPause() {
super.onPause();
getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
}
#Override
public void onResume() {
super.onResume();
getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
}
I'm using OnSharedPreferenceChangeListener in my main activity:
private SharedPreferences settings;
private OnSharedPreferenceChangeListener listener;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
settings = PreferenceManager.getDefaultSharedPreferences(this);
listener = new OnSharedPreferenceChangeListener() {
#Override
public void onSharedPreferenceChanged(SharedPreferences arg0, String arg1) {
MainActivity.this.refreshDisplay(null);
}
};
settings.registerOnSharedPreferenceChangeListener(listener);
}
public void refreshDisplay(View view){
//code
}
this way I should implement this listener inside all of my activities. because of I've menu in my action bar called settings. I want to know Is there any generic way(defining that listener inside a class and call it in other activities) to do that?
Thanks in advanced.
Create a SharedPrefsListenerActivity Class which extends Activity.
Add the listener inside SharedPrefsListenerActivity.
Make sure all other activities extend SharedPrefsListenerActivity.
Create BaseActivity implementing the listener (OnSharedPreferenceChangeListener())
Use BaseActivity (YourActivity extends BaseActivity)
How would I add a listener so that when a preference is changed (i.e. CheckBoxPreference) some
method is executed (i.e. Toast)
Preferences.java
public class Preferences extends PreferenceActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.preferences);
}
}
Main.java
[...]
SharedPreferences preferences;
preferences = PreferenceManager.getDefaultSharedPreferences(this);
[...]
http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/app/AdvancedPreferences.html