I've created a Master-Detail Flow application, and I'm using all of the default files that Eclipse/Android creates. I created a project using the template, and haven't modified anything in it, except to add the methods discussed below for deleting the item.
I need to implement an onItemLongClickListener so that when I longpress an item in the list, that item is deleted. I don't want an alert or a confirmation or to select multiple items, I just want the one I longclick to go away.
I've found several tutorials on the subject, but my issue is that they aren't using fragments, so I'm getting a bit confused about what methods go where. (This is the one I'm mostly working with: AndroidForBeginners)
If I'm understanding correctly, I should only be using the ItemListActivity and ItemListFragment. I understand that methods in the Fragment will be called in the Activity (such as the default onItemSelected that comes with the template). I understand that the removeItemFromList method (from the linked tutorial) removes the item from the array and notifies the adapter to update the list. My problem is, I don't know where the array and adapter are within the Master-Detail fragments and activities. There's an ArrayList in the DummyContent, so I thought maybe if I call removeItem in the fragment, then send it to the Activity, then call it from the DummyContent class it would work. But it doesn't, and I'm stuck.
Any advice would be much appreciated!
As requested, here is the code I'm currently using. As I said, just the default android template.
ItemListActivity.java
package Andrea.deletelistitem;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
/**
* An activity representing a list of Items. This activity
* has different presentations for handset and tablet-size devices. On
* handsets, the activity presents a list of items, which when touched,
* lead to a {@link ItemDetailActivity} representing
* item details. On tablets, the activity presents the list of items and
* item details side-by-side using two vertical panes.
* <p>
* The activity makes heavy use of fragments. The list of items is a
* {@link ItemListFragment} and the item details
* (if present) is a {@link ItemDetailFragment}.
* <p>
* This activity also implements the required
* {@link ItemListFragment.Callbacks} interface
* to listen for item selections.
*/
public class ItemListActivity extends FragmentActivity
implements ItemListFragment.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_item_list);
if (findViewById(R.id.item_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.
((ItemListFragment) getSupportFragmentManager()
.findFragmentById(R.id.item_list))
.setActivateOnItemClick(true);
}
// TODO: If exposing deep links into your app, handle intents here.
}
/**
* Callback method from {@link ItemListFragment.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(ItemDetailFragment.ARG_ITEM_ID, id);
ItemDetailFragment fragment = new ItemDetailFragment();
fragment.setArguments(arguments);
getSupportFragmentManager().beginTransaction()
.replace(R.id.item_detail_container, fragment)
.commit();
} else {
// In single-pane mode, simply start the detail activity
// for the selected item ID.
Intent detailIntent = new Intent(this, ItemDetailActivity.class);
detailIntent.putExtra(ItemDetailFragment.ARG_ITEM_ID, id);
startActivity(detailIntent);
}
}
}
ItemListFragment.java
package Andrea.deletelistitem;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import Andrea.deletelistitem.dummy.DummyContent;
/**
* A list fragment representing a list of Items. This fragment
* also supports tablet devices by allowing list items to be given an
* 'activated' state upon selection. This helps indicate which item is
* currently being viewed in a {@link ItemDetailFragment}.
* <p>
* Activities containing this fragment MUST implement the {@link Callbacks}
* interface.
*/
public class ItemListFragment 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 ItemListFragment() {
}
@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;
}
}
DummyContent.java
package Andrea.deletelistitem.dummy;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Helper class for providing sample content for user interfaces created by
* Android template wizards.
* <p>
* TODO: Replace all uses of this class before publishing your app.
*/
public class DummyContent {
/**
* An array of sample (dummy) items.
*/
public static List<DummyItem> ITEMS = new ArrayList<DummyItem>();
/**
* A map of sample (dummy) items, by ID.
*/
public static Map<String, DummyItem> ITEM_MAP = new HashMap<String, DummyItem>();
static {
// Add 3 sample items.
addItem(new DummyItem("1", "Item 1"));
addItem(new DummyItem("2", "Item 2"));
addItem(new DummyItem("3", "Item 3"));
}
private static void addItem(DummyItem item) {
ITEMS.add(item);
ITEM_MAP.put(item.id, item);
}
/**
* A dummy item representing a piece of content.
*/
public static class DummyItem {
public String id;
public String content;
public DummyItem(String id, String content) {
this.id = id;
this.content = content;
}
@Override
public String toString() {
return content;
}
}
}
This is the method from the tutorial:
protected void removeItemFromList(int position) {
final int deletePosition = position;
AlertDialog.Builder alert = new AlertDialog.Builder(
MainActivity.this);
alert.setTitle("Delete");
alert.setMessage("Do you want delete this item?");
alert.setPositiveButton("YES", new OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TOD O Auto-generated method stub
// main code on after clicking yes
arr.remove(deletePosition);
adapter.notifyDataSetChanged();
adapter.notifyDataSetInvalidated();
}
});
alert.setNegativeButton("CANCEL", new OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
dialog.dismiss();
}
});
alert.show();
}
This is the method with my modifications, to remove the confirmation alert:
protected void removeItemFromList(int position) {
arr.remove(position);
adapter.notifyDataSetChanged();
adapter.notifyDataSetInvalidated();
}
In this method, I think ITEMS from the DummyContent would replace the arr array, because it's an ArrayList. I'm not sure about the adapter, though.
There's a method on any Fragment called onActivityCreated You want to @Override that method.
Then, inside it, using getListView() you can attach an onLongItemClickListener().
Like so:
getListView().setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
//Here you implement your code. Basically delete an item from
// the underlying data structure of your adapter, and then...
setListAdapter(.....); //re-set the list adapter.
return false;
}
});