How to delete duplicated Objects from SQLite query result from android

Question

what I am trying to do is delete the duplicates from a query result. I tried to use HashSet but did not quite work. So I am trying to delete the duplicates from the query directly.

This is the query

public List<SaleHeader> getSaleHeadersDevolutionsToSync(){
    List<SaleHeader> saleHeaderList =new Select().from(SaleHeader.class)
            .innerJoin(Devolution.class)
            .on("Devolutions.idSaleHeader = SaleHeaders.idSaleHeader")
            .where("Devolutions.idDevolution < 0").execute();
    Log.e("Tag", String.valueOf(saleHeaderList));
    return saleHeaderList;
}

This is the HashSet I tried

            Set<SaleHeader> set = new HashSet<>(saleHeaderDevolutionList);
            saleHeaderDevolutionList.clear();
            saleHeaderDevolutionList.addAll(set);

Any help or sugestions on what to look for would be great, thanks

Answer 1

Finally I figure it out on how to implement a direct query

    List<SaleHeader> saleHeaderListQuery =
            SQLiteUtils.rawQuery(SaleHeader.class,
                    "SELECT DISTINCT Devolutions.idsaleheader FROM Devolutions LEFT JOIN SaleHeaders ON Devolutions.idSaleHeader = SaleHeaders.idsaleheader " +
                            "WHERE Devolutions.iddevolution < ?",
                    new String[] { "0" });