java - Refresh JTable after delete and insert in JTabbedPane -

i want jtable auto-update when adding or deleting data table, can't refresh: can me find mistakes here?

package gui;  public class cek extends jframe implements actionlistener,  listselectionlistener     {      public static connectionmanager conn = new connectionmanager();      private string driver = "com.mysql.jdbc.driver";     private string url = "jdbc:mysql://localhost/db_uas";     private string username = "root";     private string password = "shasa";      defaulttablemodel tablemodel = new defaulttablemodel();     private jtabbedpane tabpane;     private jlabel label1;     private jpanel panel1,panel2,panel3;     private jtable table = new jtable();     private string judulkolom[] = {"mata uang" , "harga"};     private defaulttablemodel tbm;     private int nmax = 50;     int harga_kamar;     listselectionmodel listmod;     int row=0;       object data[][] = new object[nmax][2];      jlabel lblmatauang = new jlabel("mata uang :");     jtextfield jtfmatauang = new jtextfield();      jlabel lbleditharga = new jlabel("edit harga :");     jtextfield jtfeditharga = new jtextfield();       jbutton jbedit = new jbutton("update");        jlabel lbladdmatauang = new jlabel("mata uang baru :");     jlabel lbladdharga = new jlabel("nilai tukar : rp.");      jtextfield jtfaddmatauang = new jtextfield();     jtextfield jtfaddharga = new jtextfield();      jbutton btnadd = new jbutton("add");     jbutton btnpaiipaii = new jbutton("exittt");     jbutton btndelete = new jbutton("delete");      string ket;      arraylist<string> shasa1 = new arraylist<>();      jlabel lbldeletemu = new jlabel("delete mata uang : ");      public cek(){         super("list data");         setsize(500, 500);         setresizable(false);         setlocationrelativeto (null);         setvisible (true);            tabpane = new jtabbedpane ();         label1 = new jlabel ("panel pertama", swingconstants.center);           jbedit.addactionlistener(this);         btnadd.addactionlistener(this);         btnpaiipaii.addactionlistener(this);         btndelete.addactionlistener(this);           for(int i=0;i<data.length;i++){             data[i][0] = new object();             data[i][1] = new object();         }                 table =  new jtable();         tbm = new defaulttablemodel(new object[][]{}, judulkolom);         table.setmodel(tbm);         table.setbounds(5, 5, 300, 300);          tampil();         lblmatauang.setbounds(330, 10, 200, 50);         jtfmatauang.setbounds(330, 50, 150, 20);         lbleditharga.setbounds(330, 60, 200, 50);         jtfeditharga.setbounds(330, 100, 150, 20);         jbedit.setbounds(330, 130, 80, 30);          btnpaiipaii.setbounds(330, 180, 100, 20);         jtfmatauang.seteditable(false);           listmod =  table.getselectionmodel();         listmod.setselectionmode(listselectionmodel.single_selection);         listmod.addlistselectionlistener(this);          panel1 = new jpanel ();         panel1.setlayout(null);         panel1.add(table);         panel1.add(lblmatauang);         panel1.add(jtfmatauang);         panel1.add(lbleditharga);         panel1.add(jtfeditharga);         panel1.add(jbedit);           panel1.add(btnpaiipaii);            panel2 = new jpanel ();         panel2.setlayout(null);          lbladdmatauang.setbounds(20, 20, 100, 30);         jtfaddmatauang.setbounds(150, 20, 150, 30);         lbladdharga.setbounds(20, 100, 100, 30);         jtfaddharga.setbounds(150, 100, 150, 30);         btnadd.setbounds(100, 300, 100, 30);          panel2.add(lbladdmatauang);         panel2.add(jtfaddmatauang);         panel2.add(lbladdharga);         panel2.add(jtfaddharga);         panel2.add(btnadd);             panel3 = new jpanel();         panel3.setlayout(null);           showcombobox();         string daftarmatauang[] = shasa1.toarray(new string[shasa1.size()]);         jcombobox matauang = new jcombobox(daftarmatauang);         matauang.addactionlistener(this);          matauang.setbounds(20, 20, 300, 30);         lbldeletemu.setbounds(20, 50, 250, 30);         btndelete.setbounds(150, 250, 100, 30);          panel3.add(matauang);         panel3.add(lbldeletemu);         panel3.add(btndelete);          tabpane.addtab ("update/perubahan", null, panel1);          tabpane.addtab("add", null,panel2);         tabpane.addtab("delete", null,panel3);         getcontentpane().add(tabpane);        }      public void resettable()     {         (int = 0; < table.getrowcount(); i++) {             (int j = 0; j < table.getcolumncount(); j++) {                 table.setvalueat(null, i, j);             }         }         refreshtable();     }     public void showcombobox()     {          conn.connect();             string query = "select mata_uang nilai_tukar";              try             {                 statement stmt = conn.con.createstatement();                 resultset rs = stmt.executequery(query);                  while(rs.next())                 {                     shasa1.add(rs.getstring("mata_uang"));                                                   }             }             catch(exception e1)             {                 e1.printstacktrace();             }             conn.disconnect();     }      public void tampil()     {         try         {            int row = tbm.getrowcount();            tbm.addrow(judulkolom);             connectionmanager conn =  new connectionmanager();            conn.connect();            statement stmt = conn.con.createstatement();            resultset rs = stmt.executequery("select * nilai_tukar");            int no=0;            while(rs.next())            {                 no++;                 string no_kamar = rs.getstring("mata_uang");                 double harga  = rs.getdouble("harga");                 data[no][0] = no_kamar;                 data[no][1] = harga;                 tbm.addrow(data[no]);                 row++;            }            rs.close();            conn.disconnect();         }         catch(exception exc)         {            exc.printstacktrace();         }     }     public void refreshtable(){          table.setvalueat("mata uang", row, 0);         table.setvalueat("harga", row, 1);          row++;             try {                 class.forname(driver);                 connection conns = drivermanager.getconnection(url, username, password);                 preparedstatement query = (preparedstatement) conns.preparestatement("select * nilai_tukar");                 resultset rs = query.executequery();                 while (rs.next()) {                     table.setvalueat(rs.getstring("mata_uang"), row, 0);                     table.setvalueat(rs.getdouble("harga"), row, 1);                     row++;                 }             } catch (sqlexception e) {                 // todo auto-generated catch block                 e.printstacktrace();             } catch (classnotfoundexception e) {                 // todo auto-generated catch block                 e.printstacktrace();             }       }        @override     public void actionperformed(actionevent e)      {         if(e.getsource()==jbedit)         {             string mu ;             double temp =0;             mu = jtfmatauang.gettext();             temp = double.parsedouble(jtfeditharga.gettext());             try             {                 connectionmanager conn =  new connectionmanager();                 conn.connect();                 string query ="update nilai_tukar set harga="+temp+" mata_uang='"+mu+"'";                 statement stmt1 = conn.con.createstatement();                 int updatefield = stmt1.executeupdate(query);                 joptionpane.showmessagedialog(null, "data anda terupdate !!");                 resettable();              }              catch (exception e2)              {                 e2.printstacktrace();             }         }          if(e.getsource()==btnadd)         {             connectionmanager conn =  new connectionmanager();             conn.connect();             if(!jtfaddharga.gettext().equals("") && !jtfaddmatauang.gettext().equals(""))             {                 double h = double.parsedouble(jtfaddharga.gettext()) ;                 string mu = jtfaddmatauang.gettext();                 string query = "insert nilai_tukar values(?,?)";                 try                 {                     preparedstatement stmt = (preparedstatement) conn.con.preparestatement(query);                     stmt.setstring(1, mu);                     stmt.setdouble(2, h);                     stmt.executeupdate();                     joptionpane.showmessagedialog(null, "new data added succecfully");                     table.repaint();                  }                 catch(exception e1){                     e1.printstacktrace();                 }                 conn.disconnect();             }             else             {                 joptionpane.showmessagedialog(null, "data harus diisi");             }         }          if(e.getsource() == btnpaiipaii)         {             dispose();             new gui();         }         try         {             jcombobox<string> test = (jcombobox)e.getsource();             ket = (string) test.getselecteditem();             lbldeletemu.settext("delete mata uang : " + ket);         }         catch (exception e2)         {          }         if(e.getsource() == btndelete)         {              connectionmanager conn =  new connectionmanager();             conn.connect();             system.out.println(ket);             string sql = "delete nilai_tukar mata_uang = '"+ket+"'";             try             {                 preparedstatement stmt = (preparedstatement) conn.con.preparestatement(sql);                 stmt.executeupdate();                                system.out.println(ket);                 joptionpane.showmessagedialog(null, "data deleted succesfully");                  conn.connect();                 string query2 = "select mata_uang nilai_tukar";                  try                 {                     statement stmt2 = conn.con.createstatement();                     resultset rs2 = stmt2.executequery(query2);                      while(rs2.next())                     {                         system.out.println(rs2.getstring("mata_uang"));                         shasa1.add(rs2.getstring("mata_uang"));                                                      }                 }                 catch(exception e1)                 {                     e1.printstacktrace();                 }                 conn.disconnect();                  showcombobox();                 string daftarmatauang[] = shasa1.toarray(new string[shasa1.size()]);                 jcombobox matauang = new jcombobox(daftarmatauang);                 matauang.addactionlistener(this);                  matauang.setbounds(20, 20, 300, 30);                  panel3.add(matauang);              }             catch(exception e1){                 e1.printstacktrace();             }             conn.disconnect();         }       }      @override     public void valuechanged(listselectionevent e) {         int maxrows;            int[] selrows;            object value;          if (!e.getvalueisadjusting()) {                      selrows = table.getselectedrows();              if (selrows.length > 0) {                  jtfmatauang.settext((string) data[table.getselectedrow()][0]);                  jtfeditharga.settext(data[table.getselectedrow()][1].tostring());              }           }     }        public static void main(string[] args) {         new cek();     }  }