where clause not working with AND, JDBC/JAVA/SQL

The code below works fine when i remove this part (+"AND ref = '"+Mref.getText()+"'");)  but doesn’t work with it:

pst1=  con.prepareStatement(" SELECT  price from article where barcode = '"+Mbarcode.getText()+"'" +"AND ref = '"+Mref.getText()+"'");
ResultSet rs1 ;
rs1= pst1.executeQuery(); ```

this is the table named article in my database

barcodename  |qty    |price  |vendor |ref   maxremise