Removing Duplicates From ListView android

I am posting my code, I am unable to remove the duplicate values from the listview? Can someone please help me? Thanks in advance! I am pasting my code here and I have used BaseAdapter.

@Override
            public void onCompleted(final List<Recommendable> result) {
                android.util.Log.w("suggestionview>>>>>", "suggestion"+ result.size());
                ((Activity) mContext).runOnUiThread(new Runnable() {
                    public void run() {
                        Iterator<Recommendable> itr = result.iterator();
                        while (itr.hasNext()) {
                            Recommendable element = itr.next();
                            suggestions.add(element);
                            android.util.Log.w("suggestionview", "Adding elements::>"+suggestions.add(element));
                        }
                        suggestionListView.setAdapter(new Suggestiondapter(mContext));
                        android.util.Log.w("suggestionview","suggestion adapter Values::>"+suggestionListView);
                    }
                });

And the second of the code

public class Suggestiondapter extends BaseAdapter {


    // private LayoutInflater mInflater = null;
    private Context mContext;

    public Suggestiondapter(Context mContext) {
        this.mContext=mContext;
        android.util.Log.w("Suggestion Adapter","vlues are comming.....");
    }

    @Override
    public int getCount() {
        android.util.Log.w("suugestion adapter","suggstion size::>"+suggestions.size());
        return suggestions.size();
    }

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

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Recommendable recommendable = suggestions.get(position);
        if(convertView==null){
            andr开发者_如何学Gooid.util.Log.w("convertView", "adaptervalues........::>"+ recommendable.Program);
            android.util.Log.w("series conveter", "program series values::>"+recommendable.Series);
            convertView = new HeaderView(mContext, recommendable.Program,recommendable.Series, SuggestionView.class);
        }else{
            Toast.makeText(mContext, "HelloView", Toast.LENGTH_SHORT);
        }
        return convertView;
    }
};

You could use that code:

    private static HashSet<String> hs = new HashSet<String>();
    private static ArrayList<String> list= new ArrayList<String>();

    for(int i=0; i<list.size(); i++){
        hs.add(list.get(i));

    }

    list.clear();
    list.addAll(hs);