get all items from custom listview which contains a checked checkbox

I have a custom ListView with a checkbox in each item. A user can select a maximum of 3 items from the listview. After selecting items, on a button click i want to get the user selected items. My Adapter class is

public class CBAdapter extends BaseAdapter {

Context context;
public String[] englishNames;
LayoutInflater inflater;
CheckBox[] checkBoxArray;
LinearLayout[] viewArray;
private boolean[] checked;
private ArrayList<NotificationModel> planList;
int count=0;
private LayoutInflater mInflater;
public HashMap<String,String> checked2 = new HashMap<String,String>();

public CBAdapter(Context context, ArrayList<NotificationModel> planList){
    this.planList = planList;
    mInflater = LayoutInflater.from(context);
    this.context = context;
    inflater=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

public int getCount() {
    return planList.size();
}

public Object getItem(int position) {
    // TODO Auto-generated method stub
    return null;
}

public long getItemId(int position) {
    // TODO Auto-generated method stub
    return 0;
}

public void setCheckedItem(int item) {


    if (checked2.containsKey(String.valueOf(item))){
        checked2.remove(String.valueOf(item));
    }

    else {
        checked2.put(String.valueOf(item), String.valueOf(item));
    }
}
public HashMap<String, String> getCheckedItems(){
    return checked2;
}

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

    ViewHolder holder;

    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.pref_list, null);
        holder = new ViewHolder();
        holder.contactName = (TextView) convertView.findViewById(R.id.name);
        holder.checkBox = (CheckBox) convertView.findViewById(R.id.chk);
        convertView.setTag(holder);

    } else {
        holder = (ViewHolder) convertView.getTag();
    }

    NotificationModel browsePlan = planList.get(position);

    holder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener()
    {

        @Override
        public void onCheckedChanged(CompoundButton checkboxView, boolean isChecked)
        {
            NotificationModel c = (NotificationModel) checkboxView.getTag();

            setCheckedItem(position);

            if(isChecked)
            {
                count++;
            }
            else if(!isChecked)
            {
                count--;
            }
            if(count >= 4)
            {
                Toast.makeText(context, "You can only select a maximum of 3 preference", Toast.LENGTH_LONG).show();
                checkboxView.setChecked(false);
                count--;
            }
            else
            {
                c.setChecked(isChecked);
            }
        }
    });

    holder.checkBox.setTag(browsePlan);
    holder.checkBox.setChecked(browsePlan.getChecked());
    holder.contactName.setText(browsePlan.getName());

    return convertView;

}

class ViewHolder {
    TextView contactName;
    CheckBox  checkBox;
}

}

I tried with the following method in my button's onClick method, but it getting Exception

proceed.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            Iterator<String> it = adapter.getCheckedItems().values().iterator();

            for (int i=0;i<adapter.getCheckedItems().size();i++){
                adapter.getItem(Integer.parseInt(it.next()));
                Log.e("success",""+adapter.getItem(Integer.parseInt(it.next())));
            }
        }
    });

I am not sure that the method i'm using is correct or not. The error i'm getting from this way is

"java.util.NoSuchElementException".

How can i get items from listview with checked boxes?