Button sortTitle = (Button)this.findViewById(R.id.btn_sortTitle);
Button sortRating = (Button)this.findViewById(R.id.btn_sortRating);
Button sortDownloads = (Button)this.findViewById(R.id.btn_sortDownloads);

sortTitle.setOnClickListener(new OnClickListener() {
    public void onClick(View v) {
        //Make sure it isn't the same thing that was just sorted
        if (lastSort != "title") {
            loadListView(system, sort);
            lastSort = "title";
        }
    }
});