I am working on an application where i use a background service to send a request to a server the response is then stored in a database and display the data dynamically as receiving the answers from the background service and saving them in the database, knowing that i'm using a
ListView
to display the data from the database. how can i refresh the activity every time i save new data in the database? i have triyed displaying the data after a click it's working how can i do it dynamically?
Assuming you are using a true service or not an AsyncTask.
Use a BroadcastReceiver pattern. Send the broadcast in your service.
LocalBroadcastManager.getInstance(context).sendBroadcast(new Intent("data_changed"));
Declare your receiver in activity containing your listview
private BroadcastReceiver dataChangeReceiver= new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// update your listview
}
};
Register and unregister it
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
IntentFilter inF = new IntentFilter("data_changed");
LocalBroadcastManager.getInstance(this).registerReceiver(dataChangeReceiver,inF);
}
@Override
protected void onPause() {
super.onPause();
LocalBroadcastManager.getInstance(this).unregisterReceiver(dataChangeReceiver);
}
Try CursorLoader. Loader monitors the data source and brings new results when content changes.
Example from official reference
Here is the full implementation of a Fragment that displays a ListView containing the results of a query against the contacts content provider. It uses a CursorLoader to manage the query on the provider
public static class CursorLoaderListFragment extends ListFragment
implements OnQueryTextListener, OnCloseListener,
LoaderManager.LoaderCallbacks<Cursor> {
// This is the Adapter being used to display the list's data.
SimpleCursorAdapter mAdapter;
// The SearchView for doing filtering.
SearchView mSearchView;
// If non-null, this is the current filter the user has provided.
String mCurFilter;
@Override public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Give some text to display if there is no data. In a real
// application this would come from a resource.
setEmptyText("No phone numbers");
// We have a menu item to show in action bar.
setHasOptionsMenu(true);
// Create an empty adapter we will use to display the loaded data.
mAdapter = new SimpleCursorAdapter(getActivity(),
android.R.layout.simple_list_item_2, null,
new String[] { Contacts.DISPLAY_NAME, Contacts.CONTACT_STATUS },
new int[] { android.R.id.text1, android.R.id.text2 }, 0);
setListAdapter(mAdapter);
// Start out with a progress indicator.
setListShown(false);
// Prepare the loader. Either re-connect with an existing one,
// or start a new one.
getLoaderManager().initLoader(0, null, this);
}
public static class MySearchView extends SearchView {
public MySearchView(Context context) {
super(context);
}
// The normal SearchView doesn't clear its search text when
// collapsed, so we will do this for it.
@Override
public void onActionViewCollapsed() {
setQuery("", false);
super.onActionViewCollapsed();
}
}
@Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
// Place an action bar item for searching.
MenuItem item = menu.add("Search");
item.setIcon(android.R.drawable.ic_menu_search);
item.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM
| MenuItem.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW);
mSearchView = new MySearchView(getActivity());
mSearchView.setOnQueryTextListener(this);
mSearchView.setOnCloseListener(this);
mSearchView.setIconifiedByDefault(true);
item.setActionView(mSearchView);
}
public boolean onQueryTextChange(String newText) {
// Called when the action bar search text has changed. Update
// the search filter, and restart the loader to do a new query
// with this filter.
String newFilter = !TextUtils.isEmpty(newText) ? newText : null;
// Don't do anything if the filter hasn't actually changed.
// Prevents restarting the loader when restoring state.
if (mCurFilter == null && newFilter == null) {
return true;
}
if (mCurFilter != null && mCurFilter.equals(newFilter)) {
return true;
}
mCurFilter = newFilter;
getLoaderManager().restartLoader(0, null, this);
return true;
}
@Override public boolean onQueryTextSubmit(String query) {
// Don't care about this.
return true;
}
@Override
public boolean onClose() {
if (!TextUtils.isEmpty(mSearchView.getQuery())) {
mSearchView.setQuery(null, true);
}
return true;
}
@Override public void onListItemClick(ListView l, View v, int position, long id) {
// Insert desired behavior here.
Log.i("FragmentComplexList", "Item clicked: " + id);
}
// These are the Contacts rows that we will retrieve.
static final String[] CONTACTS_SUMMARY_PROJECTION = new String[] {
Contacts._ID,
Contacts.DISPLAY_NAME,
Contacts.CONTACT_STATUS,
Contacts.CONTACT_PRESENCE,
Contacts.PHOTO_ID,
Contacts.LOOKUP_KEY,
};
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
// This is called when a new Loader needs to be created. This
// sample only has one Loader, so we don't care about the ID.
// First, pick the base URI to use depending on whether we are
// currently filtering.
Uri baseUri;
if (mCurFilter != null) {
baseUri = Uri.withAppendedPath(Contacts.CONTENT_FILTER_URI,
Uri.encode(mCurFilter));
} else {
baseUri = Contacts.CONTENT_URI;
}
// Now create and return a CursorLoader that will take care of
// creating a Cursor for the data being displayed.
String select = "((" + Contacts.DISPLAY_NAME + " NOTNULL) AND ("
+ Contacts.HAS_PHONE_NUMBER + "=1) AND ("
+ Contacts.DISPLAY_NAME + " != '' ))";
return new CursorLoader(getActivity(), baseUri,
CONTACTS_SUMMARY_PROJECTION, select, null,
Contacts.DISPLAY_NAME + " COLLATE LOCALIZED ASC");
}
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
// Swap the new cursor in. (The framework will take care of closing the
// old cursor once we return.)
mAdapter.swapCursor(data);
// The list should now be shown.
if (isResumed()) {
setListShown(true);
} else {
setListShownNoAnimation(true);
}
}
public void onLoaderReset(Loader<Cursor> loader) {
// This is called when the last Cursor provided to onLoadFinished()
// above is about to be closed. We need to make sure we are no
// longer using it.
mAdapter.swapCursor(null);
}
}
You can refresh the data of activity by using Broadcast receiver. To update
the view in UI you can go for .invalidate() in the view which you want to refresh. For Example
RelativeLayout slidingUpLayout=(RelativeLayout) view.findViewById(R.id.slidingLayout);
slidingUpLayout.invalidate();
Now Whatever the components like Button, Imageview etc... inside this relativelayout will be redrawn to refresh the latest updates. Have a look @ this Related ques, How android draws, Invalidate(), requestLayout()
