Question

My array list somehow becomes populated.

Look at this code:

final ListView list = getListView();
boolean threadNeeded = true;
//settings
list.setItemsCanFocus(false);
Bundle extras = getIntent().getExtras();
allFriends = getIntent().getParcelableExtra("shibby.whisper.allFriends");
selectedFriends = getIntent().getParcelableExtra("shibby.whisper.selectedFriends");
System.out.println("JUST ENTERED ACTIVITY : "+selectedFriends.getPositions());

if(extras !=null) {
    maxPlayers = extras.getInt("max_players");
}

if(allFriends != null){
    if(!allFriends.getIds().isEmpty()){
        threadNeeded = false;
    }
}

if(selectedFriends == null){
    System.out.println("selectedFriends is null before callback from ListActivity");
    selectedFriends = new PlayerList();
}

list.setOnItemClickListener(new OnItemClickListener() {
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        FacebookFriendsAdapter a = (FacebookFriendsAdapter) list.getAdapter();
        //select item
        boolean isSelected = a.toggleSelected(new Integer(position));

        //if reached maximum players and have selected a new user
        if(((maxPlayers+1 == a.getMaxPlayersCounter() && maxPlayers != 0) && isSelected)
            || (maxPlayers == 0 && a.getMaxPlayersCounter() == maxAvailablePlayers+1)){
            Log.e("addfriends","Max Players Reached");
            a.toggleSelected(new Integer(position));        
            final Dialog dialog = new Dialog(FacebookFriendsListActivity.this, R.style.CustomDialogTheme );
            dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
            dialog.setContentView(R.layout.maxplayers);
            dialog.setCancelable(true);
            // set the custom dialog components - text, image and button
            Button dialogButton = (Button)       dialog.findViewById(R.id.max_players_dismiss_btn);
            // if button is clicked, close the custom dialog
            dialogButton.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View v) {
                    dialog.dismiss();
                }
            });
            dialog.show();
        }
    }
});

m_friends = new ArrayList<Player>();
this.m_adapter = new FacebookFriendsAdapter(this, R.layout.facebbok_friends_item, m_friends);

//set the selected friends on the adapter to remember earlier picks
if(selectedFriends != null){
    oldPositions = selectedFriends.getPositions();
    m_adapter.setSelectedIds(selectedFriends.getPositions());
    m_adapter.setMaxPlayersCounter(selectedFriends.getIds().size());
    System.out.println("Max player selected Is : "+maxPlayers+" And Selected Players Counter Is :" +m_adapter.getMaxPlayersCounter());
}

When the activity starts, the selectedFriends.getPosition() returns empty.

When I click a button I do this action:

if(oldPositions != null){
    System.out.println("This is old positions : " + oldPositions);
}

Which is populated (by the new position), but I don’t see why. Am I referencing something I shouldn’t? Do I override the data in memory?

EDIT : This happens after I select some friends from the ListView. toggleSelected() adds or removes item from an inner ArrayList.

Answer 1

I think your mistake is assuming that this line makes a copy of whatever getPositions return:

oldPositions = selectedFriends.getPositions();

Actually it only makes a copy of the reference – it doesn’t make a shallow copy of the entire list.

You probably want something like this (I’m just guessing the type):

oldPositions = new ArrayList<Position>(selectedFriends.getPositions());