How to let OnClick in ListView's Adapter call Activity's function

I have an Android application with a ListView in it, the ListView will setup fine but now I want a image in the ListView to be clickable. I do this by using 2 classes, the Activity class (parent) and an ArrayAdapter to fill the list. In the ArrayAdapter I implement a OnClickListener for the image in the list that I want to be clickable.

So far it all works.

But now I want to run a function from the activity class when the onClick, for the image in the list, is run but I do not know how. Below are the 2 classes that I use.

First the Activity class:

public class parent_class extends Activity implements OnClickListener, OnItemClickListener
{
    child_class_list myList;
    ListView myListView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // setup the Homelist data
        myList     = new child_class_list (this, Group_Names, Group_Dates);
        myListView = (ListView) findViewById(R.id.list);

        // set the HomeList
        myListView.setAdapter( myList );
        myListView.setOnItemClickListener(this);
    }

    void function_to_run()
    {
        // I want to run this function from the LiscView Onclick
    }

    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) 
    {
        // do something
    }
}

And the ArrayAdapter from where I want to call a function from the Activity class:

public class child_class_list extends ArrayAdapter<String>
{
    // private
    private final Context context;
    private String[]        mName;
    private String[]        mDate;

    public child_class_list (Context context, String[] Name, String[] Date) 
    {
        super(context, R.layout.l_home, GroupName);
        this.context        = context;
        this.mName      = Name;
        this.mDate  = Date;
    }

    @Override
    public View ge