Develop Reference

Refresh adapter in a Fragment after DialogFragment dbflow insert

I have an activity that has 3 fragments on it with Tabs, one of them is called "TaskFragment".
In my main Activity i only load the fragments.
In TaskFragment i have a RecyclerView that is working fine and is showing the items as intended.
The problem comes, when i insert data using a DialogFragment, because it does insert data (i am using DbFlow ORM), but it does not (of course) refresh the adapter since it is in the TaskFragment fragment inside the DetailMainActivity activity as i said.
I have tried to use onResume() and onPause() in order to refresh the adapter, but they are never called since the activity does not get paused or in onresume for a DialogFragment.
I have tried aswell to use an interface, but it does not work and i have searched all over stackoverflow and google with no luck.
I leave here some of my code for you to understand better:
DetailMainActivity.java
Here in the onClick interface i show the DialogFragment to the user to input the information.
FragmentManager fm = getSupportFragmentManager();
AddSimpleTask sptask = new AddSimpleTask();
sptask.show(fm, "tag");
TaskFragment.java
In this fragment i have my RecyclerView
private void setupRecyclerView() {
mRecyclerView.setAdapter(adapter);
mRecyclerView.setLayoutManager(new GridLayoutManager(getActivity(), 2));
mRecyclerView.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
if (DetailMainActivity.FAB_Status) {
DetailMainActivity.hideFAB();
DetailMainActivity.FAB_Status = false;
}
return false;
}
});
}
private void setupAdapter() {
adapter = new DetailMainTaskAdapter(simpleTaskList, this);
}
AddSimpleTask
And this is my DialogFragment. I have set a setOnShowListener() in order to avoid the DialogFragment to get dismiss early.
#Override
public void onShow(DialogInterface dialogInterface) {
final AlertDialog dialog =(AlertDialog) getDialog();
if (dialog != null){
Button positiveButton = dialog.getButton(Dialog.BUTTON_POSITIVE);
Button negativeButton = dialog.getButton(Dialog.BUTTON_NEGATIVE);
positiveButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mEditTextName.getText().toString().trim().isEmpty() ||
mEditTextContent.getText().toString().trim().isEmpty() ) {
if (mEditTextName.getText().toString().trim().isEmpty()) {
mEditTextName.setError("Can not be empty");
}
if (mEditTextContent.getText().toString().trim().isEmpty()) {
mEditTextContent.setError("Can not be empty");
}
}else {
presenter.beingInsertion(mEditTextName.getText().toString().trim(), mEditTextContent.getText().toString().trim()
, foreignId);
}
}
});
negativeButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
dismiss();
}
});
}
}
If the insert is successfully achieved the onInsertSuccess method is called (i am using MVP)
#Override
public void onInsertSuccess() {
Snackbar.make(getActivity().findViewById(R.id.containerMainDetail), "Actividad agregada", Snackbar.LENGTH_SHORT).show();
dismiss();
}
I have called adapter.notifyDataSetChanged() in many places, and i also tried with a custom interface, but i can not make this work.
Sorry for the long post, but thanks in advance for your help.

There are some errors in your statement but I'll get to that later. notifyDataSetChanged() only notifies the adapter that the underlying list (or array) has changed. The implication is that you first need to requery your database and obtain the new list before calling notifyDataSetChanged() on the adapter else there is no point as the underlying list will still be the same and it will not update the adapter.
The correct way of calling this will be through your custom listener interface and not in the onPause()/onResume() callbacks as there is the possibility that the user does not enter a value and hence you will unnecessarily be querying the database. In your custom listener interface implementation, first update the list with the new data from the DB and then notify the adapter.
Which leads to the error in assumption that onPause()/onResume() callbacks do not happen when your Activity is covered by a DialogFragment - this is incorrect. The moment the activity view is even partially covered, the onPause() callback is triggered.

Android: How to refresh online data when Internet is available without creating a new Fragment?

When my MainFragment first loads, it checks for internet connectivity. If there is internet, it loads the content from online. However, if there is no internet connectivity, I replace the existing fragment MainFragment within the container main_browse_fragment with InternetConnectivityFragment.
Within InternetConnectivtyFragment, I have a Retry button that re-checks the internet, and if there is internet connectivity, I remove InternetConnectivityFragment and call popbackstack.
The problem is, when popbackstack is called, I dont know how to reload the online data from within MainFragment. The online data loading and internet check is done within onActivityCreated of MainFragment.java, but when popbackstack is called within InternetConnectivityFragment.java, the view of MainFragment is blank
Obviously this is because the fragment is not "created" and onActivityCreated is not called again, so no data is reloaded.
Here's the relevant code:
MainFragment.java:
public class MainFragment extends DetailsFragment
{
#Override
public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
setupUIElements();
if (isConnectingToInternet() == true)
{
// Call methods to load online data
}
else
{
InternetConnectivityFragment internetError = new InternetConnectivityFragment();
getFragmentManager().beginTransaction().add(R.id.main_browse_fragment, internetError).commit();
}
}
...
}
InternetConnectivityFragment.java:
public class InternetConnectivityFragment extends ErrorFragment
{
private static final String TAG = "InternetFragment";
private static final boolean TRANSLUCENT = true;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setErrorContent();
}
private void setErrorContent()
{
setImageDrawable(getResources().getDrawable(R.drawable.lb_ic_sad_cloud, null));
setMessage(getResources().getString(R.string.no_internet_message));
setDefaultBackground(TRANSLUCENT);
setButtonText(getResources().getString(R.string.retry_connection));
setButtonClickListener(new View.OnClickListener()
{
#Override
public void onClick(View arg0)
{
if (Singleton.getInstance().isConnectedToInternet() == true)
{
getFragmentManager().beginTransaction().remove(InternetConnectivityFragment.this).commit();
getFragmentManager().popBackStack();
// How to call methods to re-load online data from MainFragment????
}
}
});
}
}
I have tried to perform the following within the onClick method:
MainFragment mainFragment = new MainFragment();
getFragmentManager().beginTransaction().remove(InternetConnectivityFragment.this).commit();
getFragmentManager().popBackStack();
getFragmentManager().beginTransaction().add(R.id.main_browse_fragment, mainFragment).commit();
However, I believe this is wrong as it just adds a new fragment MainFragment on top of an already existing fragment.
Can someone point me in the right direction?
Thanks

Android multi-fragment layout in landscape mode

Although I got my code to work, I now have no idea what it's actually doing.
My app is an RSS reader, and the main content is in a Fragment containing a ListView with NewsStory objects. When a list item is clicked, it opens an Intent with the website linked from the RSS.
Now the problem is, I don't understand the Intent here, it's not the way I've ever used Intents before.
Also, I have to make it so that when I change the orientation, the original profile Fragment takes up the left half of the screen and the linked webpage takes up the right half of the screen. I've tinkered around with it, to no avail. I did a bit of research on orientation changes, but I feel like doing things with Fragments always changes how everything works. Anyway, here's the Fragment code. Any thoughts would be greatly appreciated.
public class HeadlineFragment extends Fragment {
EditText input;
Button search;
ListView headlines;
NewsDataSource ds;
public HeadlineFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v = inflater.inflate(R.layout.fragment_headline,container,false);
input = (EditText)v.findViewById(R.id.txtInput);
search = (Button)v.findViewById(R.id.btnSearch);
headlines = (ListView)v.findViewById(R.id.listView);
try {
ds = new NewsDataSource();
} catch (ExecutionException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
headlines.setAdapter(new NewsDataSourceAdapter(this.getActivity(), ds));
headlines.setOnItemClickListener(new AdapterView.OnItemClickListener()
{
#Override
public void onItemClick(AdapterView<?> parent,View view, int position, long id)
{
String url = NewsDataSource.stories[position].getLink();
Intent i = new Intent(Intent.ACTION_VIEW);
i.setData(Uri.parse(url));
startActivity(i);
}
});
return v;
}
/*
#Override
public void onConfigurationChanged(Configuration newConfig){
super.onConfigurationChanged(newConfig);
}
*/
}

Firstly, regarding that Intent, its an implicit Intent. When you set the action as ACTION_VIEW and add a URI / URL as an extra, the OS gets the message that you want to open an app that can navigate to that URI / URL.
Secondly, for showing a two-pane layout in landscape mode, you'll have to show that RSS content in a Fragment instead of an Activity as you are currently doing, and you'll have to display those Fragments side-by-side in an Activity in landscape mode. See the Retrieving a List of Contacts example for a really good explanation of how to display a multi-pane master detail layout in portrait mode.
References:
1. Intents and Intent Filters.
2. Planning for Multiple Touchscreen Sizes.

How do I save application state between Activities with embedded fragments in the backstack?

I've found a ton of conflicting information regarding the proper way to restore application state when using Fragments embedded in Activities. Please let me know if my architecture is the problem because that is totally possible. My test Weather app is architected as follows.
The main activity "ReportsActivity" contains the fragment "ReportsFragment" (This is a list of the next 10 days of Weather Reports)
ReportsFragment has an onItemClickListener that launches a new Activity "WeatherDetailActivity" and passes it an intent which contains some JSON Data that I use to populate the Weather Detail UI. This data is then presented on a fragment that the WeatherDetailActivity manages.
My problem is, when the user presses the back button, the ReportsFragment has been destroyed so it runs through its full lifecycle. I've tried a number of techniques I've found online to load the activity's data from a bundle, but no matter what I've tried so far the Intents' Extras are null in the ReportsActivity's onCreate method. (Note: the reason I need to do this is to avoid firing off an API Call each time I open my main Activity which fetches weather data from Weather Underground).
I'm struggling determining what would be the best way to construct this app: Should I have a single activity that pushes and pops Fragments that it manages? Or are multiple activities that each manage their own fragments the standard practice?
At the moment here is how I'm attempting to save my application state onto the intent. I'm trying to save the state in onPostExecute from my AsyncTask so i'm on the main thread after i've fetched my results from the API Call:
#Override
protected void onPostExecute(Report[] result){
if (result != null){
ArrayList<String>reportsArrayList = new ArrayList<String>();
Gson jsonArray = new GsonBuilder().setPrettyPrinting().create();
for (int x = 0; x < result.length; x++){
reportsArrayList.add(jsonArray.toJson(result[x], Report.class));
}
mExtras.putStringArrayList(ReportsActivity.ReportsActivityState.KEY_ACTIVITY_REPORTS,reportsArrayList);
}
}
I then attempt to restore state from the ReportsActivity's onCreate Method:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_reports);
if (savedInstanceState == null) {
Intent intent = getIntent();
mFragment = ReportsFragment.newInstance(intent
.getStringArrayListExtra(ReportsActivityState.KEY_ACTIVITY_REPORTS));
getFragmentManager().beginTransaction()
.add(R.id.container, mFragment).commit();
}
}
In all cases the StringArrayListExtra I'm trying to get from the intent return null.
This could very well be me trying to solve an Android problem with an iOS mindset, but is there not an easy way to just restore the main activity to what it was before I pushed the detail view?

I think it would be worth your while taking a look at EventBus.
Basically you can define a object holder of any kind, for example:
class WeatherData {
List<String> reports;
public WeatherData(List<String> reports) {
this.reports = reports;
}
}
Now, in an Activity or Fragment in which you wish to remember the state, or pass some state to another Activity or Fragment do:
// this removes all the hazzle of creating bundles etc
EventBus.getDefault().postSticky(new WeatherData(reports));
And any where in your code your wish to know the most recent WeatherData:
WeatherData weatherData = EventBus.getDefault().getSticky(WeatherData.class);
EventBus also has nice methods for event handling (button clicks, completion of long running processes, etc..)
The library can be found here: https://github.com/greenrobot/EventBus
And some more examples here: http://awalkingcity.com/blog/2013/02/26/productive-android-eventbus/
Some suggestions without using 3. part library:
1) Calling setRetainInstance(true) in your fragments onCreate method, what this should do is to persist public variables between instances.
Though it seems it does not work for fragments on the back stack: Understanding Fragment's setRetainInstance(boolean)
2) Hand the fragment data to your Activity, something like reading/updating ((YourActivity)getActivity()).someFragmentBundle, possibly save it in onSaveInstanceState of the Activity and retrieve it in onCreate. That is, having your Activity hold the data in-between instances.
3) You could also persist the data, saving it to a file or using SharedPreferences http://developer.android.com/training/basics/data-storage/index.html
This method has the advantage that it will enable restoring the data even after a complete kill of your app.
The Architectural question
Disclaimer: subjective opinion
I would generally say keep the Activity as 'slim' as possible, holding a range of related fragments.
Thus, having multiple Activities is fine but they should each manage a set of (or a single) related fragments that are relevant for the current Activity.

It just occurred to me to check out one of the Android Studio templates that Google Provides that I often overlooked. From Google's own templates, it appears clear that the preferred method for Master Detail Activities/Fragments is to have each Fragment Managed by their own activities (as I was attempting to achieve above).
(I should note that I was able to successfully achieve to flow that I wanted using a single Activitiy with multiple fragments and customizing the Animation and forcefully showing and hiding the up button.)
PersonListActivity.java
public class PersonListActivity extends Activity
implements PersonListFragment.Callbacks {
/**
* Whether or not the activity is in two-pane mode, i.e. running on a tablet
* device.
*/
private boolean mTwoPane;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_person_list);
if (findViewById(R.id.person_detail_container) != null) {
// The detail container view will be present only in the
// large-screen layouts (res/values-large and
// res/values-sw600dp). If this view is present, then the
// activity should be in two-pane mode.
mTwoPane = true;
// In two-pane mode, list items should be given the
// 'activated' state when touched.
((PersonListFragment) getFragmentManager()
.findFragmentById(R.id.person_list))
.setActivateOnItemClick(true);
}
// TODO: If exposing deep links into your app, handle intents here.
}
/**
* Callback method from {#link PersonListFragment.Callbacks}
* indicating that the item with the given ID was selected.
*/
#Override
public void onItemSelected(String id) {
if (mTwoPane) {
// In two-pane mode, show the detail view in this activity by
// adding or replacing the detail fragment using a
// fragment transaction.
Bundle arguments = new Bundle();
arguments.putString(PersonDetailFragment.ARG_ITEM_ID, id);
PersonDetailFragment fragment = new PersonDetailFragment();
fragment.setArguments(arguments);
getFragmentManager().beginTransaction()
.replace(R.id.person_detail_container, fragment)
.commit();
} else {
// In single-pane mode, simply start the detail activity
// for the selected item ID.
Intent detailIntent = new Intent(this, PersonDetailActivity.class);
detailIntent.putExtra(PersonDetailFragment.ARG_ITEM_ID, id);
startActivity(detailIntent);
}
}
}
PersonListFragment.java
public class PersonListFragment extends ListFragment {
/**
* The serialization (saved instance state) Bundle key representing the
* activated item position. Only used on tablets.
*/
private static final String STATE_ACTIVATED_POSITION = "activated_position";
/**
* The fragment's current callback object, which is notified of list item
* clicks.
*/
private Callbacks mCallbacks = sDummyCallbacks;
/**
* The current activated item position. Only used on tablets.
*/
private int mActivatedPosition = ListView.INVALID_POSITION;
/**
* A callback interface that all activities containing this fragment must
* implement. This mechanism allows activities to be notified of item
* selections.
*/
public interface Callbacks {
/**
* Callback for when an item has been selected.
*/
public void onItemSelected(String id);
}
/**
* A dummy implementation of the {#link Callbacks} interface that does
* nothing. Used only when this fragment is not attached to an activity.
*/
private static Callbacks sDummyCallbacks = new Callbacks() {
#Override
public void onItemSelected(String id) {
}
};
/**
* Mandatory empty constructor for the fragment manager to instantiate the
* fragment (e.g. upon screen orientation changes).
*/
public PersonListFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// TODO: replace with a real list adapter.
setListAdapter(new ArrayAdapter<DummyContent.DummyItem>(
getActivity(),
android.R.layout.simple_list_item_activated_1,
android.R.id.text1,
DummyContent.ITEMS));
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// Restore the previously serialized activated item position.
if (savedInstanceState != null
&& savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) {
setActivatedPosition(savedInstanceState.getInt(STATE_ACTIVATED_POSITION));
}
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
// Activities containing this fragment must implement its callbacks.
if (!(activity instanceof Callbacks)) {
throw new IllegalStateException("Activity must implement fragment's callbacks.");
}
mCallbacks = (Callbacks) activity;
}
#Override
public void onDetach() {
super.onDetach();
// Reset the active callbacks interface to the dummy implementation.
mCallbacks = sDummyCallbacks;
}
#Override
public void onListItemClick(ListView listView, View view, int position, long id) {
super.onListItemClick(listView, view, position, id);
// Notify the active callbacks interface (the activity, if the
// fragment is attached to one) that an item has been selected.
mCallbacks.onItemSelected(DummyContent.ITEMS.get(position).id);
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
if (mActivatedPosition != ListView.INVALID_POSITION) {
// Serialize and persist the activated item position.
outState.putInt(STATE_ACTIVATED_POSITION, mActivatedPosition);
}
}
/**
* Turns on activate-on-click mode. When this mode is on, list items will be
* given the 'activated' state when touched.
*/
public void setActivateOnItemClick(boolean activateOnItemClick) {
// When setting CHOICE_MODE_SINGLE, ListView will automatically
// give items the 'activated' state when touched.
getListView().setChoiceMode(activateOnItemClick
? ListView.CHOICE_MODE_SINGLE
: ListView.CHOICE_MODE_NONE);
}
private void setActivatedPosition(int position) {
if (position == ListView.INVALID_POSITION) {
getListView().setItemChecked(mActivatedPosition, false);
} else {
getListView().setItemChecked(position, true);
}
mActivatedPosition = position;
}
}
PersonDetailActivity.java
public class PersonDetailActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_person_detail);
// Show the Up button in the action bar.
getActionBar().setDisplayHomeAsUpEnabled(true);
// savedInstanceState is non-null when there is fragment state
// saved from previous configurations of this activity
// (e.g. when rotating the screen from portrait to landscape).
// In this case, the fragment will automatically be re-added
// to its container so we don't need to manually add it.
// For more information, see the Fragments API guide at:
//
// http://developer.android.com/guide/components/fragments.html
//
if (savedInstanceState == null) {
// Create the detail fragment and add it to the activity
// using a fragment transaction.
Bundle arguments = new Bundle();
arguments.putString(PersonDetailFragment.ARG_ITEM_ID,
getIntent().getStringExtra(PersonDetailFragment.ARG_ITEM_ID));
PersonDetailFragment fragment = new PersonDetailFragment();
fragment.setArguments(arguments);
getFragmentManager().beginTransaction()
.add(R.id.person_detail_container, fragment)
.commit();
}
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == android.R.id.home) {
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up-vs-back
//
navigateUpTo(new Intent(this, PersonListActivity.class));
return true;
}
return super.onOptionsItemSelected(item);
}
}
PersonDetailFragment.java
public class PersonDetailFragment extends Fragment {
/**
* The fragment argument representing the item ID that this fragment
* represents.
*/
public static final String ARG_ITEM_ID = "item_id";
/**
* The dummy content this fragment is presenting.
*/
private DummyContent.DummyItem mItem;
/**
* Mandatory empty constructor for the fragment manager to instantiate the
* fragment (e.g. upon screen orientation changes).
*/
public PersonDetailFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments().containsKey(ARG_ITEM_ID)) {
// Load the dummy content specified by the fragment
// arguments. In a real-world scenario, use a Loader
// to load content from a content provider.
mItem = DummyContent.ITEM_MAP.get(getArguments().getString(ARG_ITEM_ID));
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_person_detail, container, false);
// Show the dummy content as text in a TextView.
if (mItem != null) {
((TextView) rootView.findViewById(R.id.person_detail)).setText(mItem.content);
}
return rootView;
}
}

Add up button to PreferenceScreen

I can't figure out how I would go about implementing an up button in a PreferenceScreen. An up button displays a caret in your action bar next to your app icon that allows you to navigate the app's hierarchy, more info here.
I have a Preference Fragment that displays when my main activity is opened and I can get the up button to display by adding this line " getActionBar().setDisplayHomeAsUpEnabled(true);":
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getActionBar().setDisplayHomeAsUpEnabled(true);
getFragmentManager().beginTransaction()
.replace(android.R.id.content, new SettingsFragment())
.commit();
This causes the up button to display in the Preference Fragment, but I only want to show the up button when one of my PreferenceScreens is opened, allowing navigation to the main PreferenceFragment.
My app is analogous to the main settings app. Only the child screens, like Location Access, that opens from the main Settings app has the up arrow.

From this question, I simply added these two code blocks to my Preference Fragment:
#Override
public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen, Preference preference) {
super.onPreferenceTreeClick(preferenceScreen, preference);
// If the user has clicked on a preference screen, set up the action bar
if (preference instanceof PreferenceScreen) {
initializeActionBar((PreferenceScreen) preference);
}
return false;
}
And this one:
/** Sets up the action bar for an {#link PreferenceScreen} */
public static void initializeActionBar(PreferenceScreen preferenceScreen) {
final Dialog dialog = preferenceScreen.getDialog();
if (dialog != null) {
// Inialize the action bar
dialog.getActionBar().setDisplayHomeAsUpEnabled(true);
// Apply custom home button area click listener to close the PreferenceScreen because PreferenceScreens are dialogs which swallow
// events instead of passing to the activity
// Related Issue: https://code.google.com/p/android/issues/detail?id=4611
View homeBtn = dialog.findViewById(android.R.id.home);
if (homeBtn != null) {
OnClickListener dismissDialogClickListener = new OnClickListener() {
#Override
public void onClick(View v) {
dialog.dismiss();
}
};
// Prepare yourselves for some hacky programming
ViewParent homeBtnContainer = homeBtn.getParent();
// The home button is an ImageView inside a FrameLayout
if (homeBtnContainer instanceof FrameLayout) {
ViewGroup containerParent = (ViewGroup) homeBtnContainer.getParent();
if (containerParent instanceof LinearLayout) {
// This view also contains the title text, set the whole view as clickable
((LinearLayout) containerParent).setOnClickListener(dismissDialogClickListener);
} else {
// Just set it on the home button
((FrameLayout) homeBtnContainer).setOnClickListener(dismissDialogClickListener);
}
} else {
// The 'If all else fails' default case
homeBtn.setOnClickListener(dismissDialogClickListener);
}
}
}
}

If your complete application is a preferences screen, then you can make your main activity a PreferenceActivity and the sub-levels can be fragments. This way the 'up' functionality is going to be by default what you are looking for.

Have a look at this.
For the XML:
<Preference android:title="Acts like a button"
android:key="button"
android:summary="This will act like a button"/>
Then for the Java in your onCreate()
Preference button = (Preference)findPreference("button");
button.setOnPreferenceClickListener(
new Preference.OnPreferenceClickListener() {
#Override
public boolean onPreferenceClick(Preference arg0) {
//code for what you want it to do
return true;
}
});