Nsryjdtyk

I'm creating a DataSet_Collector kind of app where a user is displayed his conversation threads in ListView. The user selects spam threads. Those Threads will be sent to an excel sheet. Then the rest of the threads(The non spam) are shown and the user selects those threads that he wants to send.
So far I've displayed the threads, stored in LinkedHashMap<String, String>, in ListView using extended SimpleAdapter i.e ThreadsAdapter. The Key of the LinkedHashMap<> is the sender and the Value at that Key is the thread. I have created a layout called listView_layout_item.xml that contains two TextView and an ImageButton. Every item of the ListView is inflated with listView_layout_item.xml in getView() like the following.

ThreadsAdapter.java



public class ThreadsAdapter extends SimpleAdapter {



    private Context context;



    /**

     * Constructor

     *

     * @param context  The context where the View associated with this SimpleAdapter is running

     * @param data     A List of Maps. Each entry in the List corresponds to one row in the list. The

     *                 Maps contain the data for each row, and should include all the entries specified in

     *                 "from"

     * @param resource Resource identifier of a view layout that defines the views for this list

     *                 item. The layout file should include at least those named views defined in "to"

     * @param from     A list of column names that will be added to the Map associated with each

     *                 item.

     * @param to       The views that should display column in the "from" parameter. These should all be

     *                 TextViews. The first N views in this list are given the values of the first N columns

     */

    ThreadsAdapter(Context context, List<? extends Map<String, ?>> data, int resource, String from, int to) {

        super(context, data, resource, from, to);

        //This 'data' is an ArrayList() of LinkedHashMap<String, String>

        //first String for sender of the thread, second String for the thread

        //ListView will list sender as item and thread as subitem in 

        //every getView() instance

        this.context = context;

    }





    private class ViewHolder{

        private ImageButton threadCheck;

        private boolean isTChecked;

    }



    @SuppressLint("InflateParams")

    @Override

    public View getView(final int position, View convertView,

                        ViewGroup parent) {

        ViewHolder view;

        LayoutInflater inflater = ((Activity) context).getLayoutInflater();

        if (convertView == null) {

            convertView = inflater.inflate(R.layout.listView_layout_item, null);

            view = new ViewHolder();

            view.threadCheck =(ImageButton) convertView.findViewById(R.id.threadChecker);

            view.isTChecked = false; // in the start of the app.

            final ViewHolder finalView = view;

            view.threadCheck.setOnClickListener(new View.OnClickListener() {

                @Override

                public void onClick(View v) {

                    if(finalView.isTChecked)

                        finalView.threadCheck.setImageResource(R.drawable.circle_unchecked);

                    else

                        finalView.threadCheck.setImageResource(R.drawable.circle_checked);

                    finalView.isTChecked = !finalView.isTChecked;

                }

            });

            convertView.setTag(view);

        } else {

            view = (ViewHolder) convertView.getTag();

        }

        super.getView(position, convertView, parent);

        return convertView;

    }

}

super.getView() is called at the end of getView() because I want to use the Text and Subtext format of SimpleAdapter for ListView.

With the given code

when I click on one ImageButton of a ListView item to change it's state, other ImageButtons of other items in ListView also change their state. Why?! and how do I fix it?

And when I scroll up or down, the state of any ImageButton changes randomly. Why?! and how do I fix it?

I'm new to ListView and ListView adapters. The present answers don't make sense so I posted my own special problem.

In ListViews, rows (ViewHolders in your case) are recycled, reused, which means that you see stuff going up and down, but it's the same set of rows over and over again.

Keeping that in mind, it is not correct to store any state in the rows because when stuff gets reused, they will use state they previously had, which on first glance appears random.

What you should do is store the isTChecked state in your data. To that end, I would advise you to switch the LinkedHashMap to a ArrayList and use simple Java objects. You could have a class like this:

public class ConversationThread {

    public String sender;

    public String thread;

    public Boolean isChecked = false; /* Initially false, to match your scenario. */

}

Your adapter's getView override would become something like this:

public View getView(final int position, View convertView, ViewGroup parent) {

    /* 'getItem' would bring you the data for the provided position, once you 

     * switch from a LinkedHashMap to an ArrayList. */

    final ConversationThread conversationThread = getItem(position);



    ViewHolder view;



    if (convertView == null) {

        /* Here, the row is created for the first time, hence why you inflate

         * the XML layout. */

        LayoutInflater inflater = ((Activity) context).getLayoutInflater();

        convertView = inflater.inflate(R.layout.listView_layout_item, null);



        view = new ViewHolder();

        view.threadCheck = (ImageButton) convertView.findViewById(R.id.threadChecker);



        /* You save the ViewHolder as the View's tag, to be able to reuse it. */

        convertView.setTag(view);

    } else {

        /* Here, the row exists, so you fetch the ViewHolder to actually reuse it. */

        view = (ViewHolder) convertView.getTag();

    }



    /* Once you have your ViewHolder, old or new, you can then update it.

     * That means updating the image and using a new click listener as well. */

    if (conversationThread.isChecked)

        view.threadCheck.setImageResource(R.drawable.circle_checked);

    else

        view.threadCheck.setImageResource(R.drawable.circle_unchecked);



    view.threadCheck.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View v /* This is the actual view clicked (view.threadCheck) */) {

            /* On click, toggle the flag and then update the View. */

            conversationThread.isChecked = !conversationThread.isChecked;



            if (conversationThread.isChecked)

                v.setImageResource(R.drawable.circle_checked);

            else

                v.setImageResource(R.drawable.circle_unchecked);

        }

    });



    /* If you also need to call super, you can do so. */

    super.getView(position, convertView, parent);



    return convertView;

}

This is in no way optimal, I just tried to make things clear with moving as little code around as possible.