How to select/deselect all checkBox?

Question

I have an adapter with an imageview,a textView and a Checkbox and a button "Select all" for selecting all the checkbox. I searched a lot about how can I do this (select all checkbox) but it not worked. Can anyone explain more what should I do? Please...I have to do this urgent

Here is my adapter :

Public class LazyAdapter1 extends BaseAdapter {

        private Activity activity;
        private String[] data;
        private String[] nume;
        private LayoutInflater inflater=null;
        public ImageLoader imageLoader; 

        public LazyAdapter1(Activity a, String[] d, String[] f) {
            activity = a;
            data=d;
            nume=f;
            inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            imageLoader=new ImageLoader(activity.getApplicationContext());
        }

        public int getCount() {
            return data.length;
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public class ViewHolder{
            public TextView text;
            public ImageView image;
            public CheckBox ck;
        }



        public View getView(int position, View convertView, ViewGroup parent) {
            View vi=convertView;
            ViewHolder holder;
            if(convertView==null){
                vi = inflater.inflate(R.layout.item, null);
                holder=new ViewHolder();
                holder.text=(TextView)vi.findViewById(R.id.text);;
                holder.image=(ImageView)vi.findViewById(R.id.image);
                holder.ck=(CheckBox)vi.findViewById(R.id.chkbox);
                vi.setTag(holder);
            }
            else
                holder=(ViewHolder)vi.getTag();

            holder.text.setText(nume[position]);
            holder.image.setTag(data[position]);
            imageLoader.DisplayImage(data[position], activity, holder.image);
            return vi;
        }
    }

Thanks in advance.

Answer 1

boolean flag = true;

Now on your button click swap the value of flag

flag = !flag;
adapter.notifydatasetchanged();

Now in your getView method

public View getView(int position, View convertView, ViewGroup parent) {
    View vi = convertView;
    ViewHolder holder;
    if (convertView == null) {
        vi = inflater.inflate(R.layout.item, null);
        holder = new ViewHolder();
        holder.text = (TextView) vi.findViewById(R.id.text);
        holder.image = (ImageView) vi.findViewById(R.id.image);
        holder.ck = (CheckBox) vi.findViewById(R.id.chkbox);
        vi.setTag(holder);
    } else {
        holder = (ViewHolder) vi.getTag();
    }
    holder.ck.setChecked(flag);
    holder.text.setText(nume[position]);
    holder.image.setTag(data[position]);
    imageLoader.DisplayImage(data[position], activity, holder.image);
    return vi;
}

Answer 2

This will get all the views in your listview and will get the checkbox in each view and sets them to be checked:

List<View> listOfViews = new ArrayList<View>();
listView1.reclaimViews(listOfViews);
for (View v : listOfViews)
{
    CheckBox cb = (CheckBox)v.findViewById(R.id.checkbox);
    cb.setChecked(true);
}

UPDATE:

Before initializing the adapter, create an arraylist that contains the checkstates of all the checkboxes. Then pass this arraylist as an argument to your custom adapter and use in the getView() function (checkStates is the arraylist in the below code):

    public View getView(int position, View convertView, ViewGroup parent) {
        View vi=convertView;
        ViewHolder holder;
        if(convertView==null){
            vi = inflater.inflate(R.layout.item, null);
            holder=new ViewHolder();
            holder.text=(TextView)vi.findViewById(R.id.text);;
            holder.image=(ImageView)vi.findViewById(R.id.image);
            CheckBox checkbox = (CheckBox)vi.findViewById(R.id.chkbox);
            checkbox.setChecked(checkStates.get(position);
            holder.ck= checkbox;
            vi.setTag(holder);
        }
        else
            holder=(ViewHolder)vi.getTag();

        holder.text.setText(nume[position]);
        holder.image.setTag(data[position]);
        holder.ck.setChecked(checkStates.get(position));
        imageLoader.DisplayImage(data[position], activity, holder.image);
        return vi;
    }

Then when you want to check all the checkboxes, set all the values in the arraylist containing the checkstates of the checkboxes as true. Then call listView1.setAdapter(adapter);

Answer 3

I asigned an id to each selected item and then use a HashMap to keep track of the selected items