I have a little problem with listview. How do i clear a listview content, knowing that it has a custom adapter?

edit : the custom adapter class extends BaseAdapter, it looks like this :

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class MyAdapter extends BaseAdapter {

    private Activity activity;
    private String[] data;
    private static LayoutInflater inflater=null;

    public MyAdapter(Activity _a, String[] _str)
    {
        activity = _a;
        data = _str;
        inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    public static class ViewHolder{
        public TextView text;
    }

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

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

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

    @Override
    public View getView(int position, View view, ViewGroup parent) {
        View v = view;
        ViewHolder holder;
        if(v == null)
        {
            v = inflater.inflate(R.layout.rowa, null);
            holder=new ViewHolder();
            holder.text=(TextView)v.findViewById(R.id.dexter);
            v.setTag(holder);
        }else{
            holder=(ViewHolder)v.getTag();
        }

        holder.text.setText(data[position]);


        return v;
    }

}