ListView count Checked Items

Hello my dear Stackers,

there is a little problem that I have and I hope you'll be able to help me solve this. Let's cut to the chase.

What should my code do? -> My code should set up a ListView with CheckBoxes, then I should be able to check to boxes and afterwards to count how many boxes are check after pressing a button. Then I should pass on the Objects to the next Activity, but that should not be part of this question, I merely add this for context, it might be important to the solution.

What does my code not do? -> my code doesn't count the boxes. The listView.getCheckedItemIds().length)); line only returns 0.

After rereading the ListView, List, Adapter, View, etc. documents and trying a few different aproaches (and tutorials, some frome stackoverflow) I'm not shure how to handle this or where to start

Here is the Code --------------------> Main Class <-----------------

    package com.example.christian.listviewwithcheckbox_model;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends Activity implements AdapterView.OnItemClickListener {

    int checkCounter = 0;

    ListView listView;
    ArrayAdapter<Model> adapter;
    List<Model> list = new ArrayList<Model>();
    private Button mButton;
    private TextView mCounter;

    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.main);

        listView = (ListView) findViewById(R.id.my_list);
        adapter = new MyAdapter(this, getModel());
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(this);


        mCounter = (TextView) findViewById(R.id.counter_text);

        mButton = (Button) findViewById(R.id.count_button);
        mButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mCounter.setText(String.format("%d", listView.getCheckedItemIds().length));
            }
        });
    }



    @Override
    public void onItemClick(AdapterView<?> arg0, View v, int position, long arg3) {
        TextView label = (TextView) v.getTag(R.id.label);
        CheckBox checkbox = (CheckBox) v.getTag(R.id.check);
        Toast.makeText(v.getContext(), label.getText().toString() + " " + isCheckedOrNot(checkbox), Toast.LENGTH_LONG).show();
    }

    private String isCheckedOrNot(CheckBox checkbox) {
        if (checkbox.isChecked()) {
            return "is checked";
        } else {
             return "is not checked";
        }
    }

    private List<Model> getModel() {
        list.add(new Model("Linux"));
        list.add(new Model("Windows7"));
        list.add(new Model("Suse"));
        list.add(new Model("Eclipse"));
        list.add(new Model("Ubuntu"));
        list.add(new Model("Solaris"));
        list.add(new Model("Android"));
        list.add(new Model("iPhone"));
        list.add(new Model("Java"));
        list.add(new Model(".Net"));
        list.add(new Model("PHP"));
        list.add(new Model("Linux"));
        list.add(new Model("Windows7"));
        list.add(new Model("Suse"));
        list.add(new Model("Eclipse"));
        list.add(new Model("Ubuntu"));
        list.add(new Model("Solaris"));
        list.add(new Model("Android"));
        list.add(new Model("iPhone"));
        list.add(new Model("Java"));
        list.add(new Model(".Net"));
        list.add(new Model("PHP"));
        list.add(new Model("Linux"));
        list.add(new Model("Windows7"));
        list.add(new Model("Suse"));
        list.add(new Model("Eclipse"));
        list.add(new Model("Ubuntu"));
        list.add(new Model("Solaris"));
        list.add(new Model("Android"));
        list.add(new Model("iPhone"));
        list.add(new Model("Java"));
        list.add(new Model(".Net"));
        list.add(new Model("PHP"));
        return list;
}

    }

---

--------------> Adapter class <-------------------------

    package com.example.christian.listviewwithcheckbox_model;

import android.app.Activity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.TextView;

import java.util.List;

public class MyAdapter extends ArrayAdapter<Model> {

    private final List<Model> list;
    private final Activity context;
    boolean checkAll_flag = false;
    boolean checkItem_flag = false;

    public MyAdapter(Activity context, List<Model> list) {
        super(context, R.layout.row, list);
        this.context = context;
        this.list = list;
    }

    static class ViewHolder {
        protected TextView text;
        protected CheckBox checkbox;
    }

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

        ViewHolder viewHolder = null;
        if (convertView == null) {
            LayoutInflater inflator = context.getLayoutInflater();
            convertView = inflator.inflate(R.layout.row, null);
            viewHolder = new ViewHolder();
            viewHolder.text = (TextView) convertView.findViewById(R.id.label);
            viewHolder.checkbox = (CheckBox) convertView.findViewById(R.id.check);
            viewHolder.checkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

                @Override
                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                    int getPosition = (Integer) buttonView.getTag();  // Here we get the position that we have set for the checkbox using setTag.
                    list.get(getPosition).setSelected(buttonView.isChecked()); // Set the value of checkbox to maintain its state.
                }
            });
            convertView.setTag(viewHolder);
            convertView.setTag(R.id.label, viewHolder.text);
            convertView.setTag(R.id.check, viewHolder.checkbox);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }




        viewHolder.checkbox.setTag(position); // This line is important.

        viewHolder.text.setText(list.get(position).getName());
        viewHolder.checkbox.setChecked(list.get(position).isSelected());

    return convertView;
} }

---

-------------------> Model class <-----------------------

    package com.example.christian.listviewwithcheckbox_model;

public class Model {

    private String name;
    private boolean selected;

    public Model(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public boolean isSelected() {
        return selected;
    }

    public void setSelected(boolean selected) {
        this.selected = selected;
    }
}

---

Well, that's my problem, I sorry to open up a thread so soon after the last one, but at this point I'm in quite some trouble and need a solution. Thank you in advance and have a nice day. Eomer