swing - NullPointerException in Java TableRowSorter -


i made jtable list of chemicals in inventory can sort each columns using following code (chemicaltable name of jtable):

chemicaltable.setautocreaterowsorter(true); tablerowsorter<tablemodel> sorter1        = new tablerowsorter<tablemodel>(chemicaltable.getmodel()); chemicaltable.setrowsorter(sorter1);

then used jtextfield create searchbox keytyped listener whenever user types character table refreshes. , works.

i used code in keytypedlistener searchbox:

defaulttablemodel dm = (defaulttablemodel) chemicaltable.getmodel();  str = searchchemicaltext.gettext();          try {             string url = "jdbc:mysql://localhost/chemical inventory";             class.forname("com.mysql.jdbc.driver").newinstance();             conn = drivermanager.getconnection(url, "root", "");           } catch (exception e) {             joptionpane.showmessagedialog(this, "error occurred.", "error", joptionpane.error_message);         }          int ctr = 0;           while (ctr < chemicaltable.getrowcount()) {             chemicaltable.getmodel().setvalueat(null, ctr, 0);             chemicaltable.getmodel().setvalueat(null, ctr, 1);             chemicaltable.getmodel().setvalueat(null, ctr, 2);             ctr++;          }          int count = 0;          try {             statement stmt = conn.createstatement();             string query = "select * chemicallist name_of_reagent '%" + str + "%'";             resultset rs = stmt.executequery(query);              if (rs.next()) {                 rs = stmt.executequery(query);                  while (rs.next()) {                     string qty = null, qtyunit = null, chemstate = null, reagentname = null;                      reagentname = rs.getstring("name_of_reagent");                     qty = rs.getstring("quantity");                     qtyunit = rs.getstring("quantity_unit");                     chemstate = rs.getstring("state");                     chemicaltable.getmodel().setvalueat(reagentname, count, 0);                     chemicaltable.getmodel().setvalueat(qty + " " + qtyunit, count, 1);                     chemicaltable.getmodel().setvalueat(chemstate, count, 2);                        if (count + 1 > chemicaltable.getrowcount() - 1) {                         dm.setrowcount(chemicaltable.getrowcount() + 1);                         dm.firetablerowsinserted(0, 5);                       }                     count++;                   }             }         } catch (exception e) {             joptionpane.showmessagedialog(this, "error occurred.", "error", joptionpane.error_message);           }

my problem is: whenever sort first columns (col1, col2, or col3) , insert character in searchbox, got error message:

"exception occurred during event dispatching: java.lang.nullpointerexception"

although it's not possible debug code fragments, several things stand out:

  • in same section, reference tablemodel dm , chemicaltable.getmodel(); use single reference or verify refer same instance.

  • instead of meddling setrowcount(), use 1 of addrow() methods.

  • the defaulttablemodel methods alter model fire correct event , table automatically update accordingly; shouldn't have yourself.


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