java - My new dataModel doesn't replace the old one in my JList [UPDATED] -

i'm working in little program allows place things on map, give name or description. places can have category choose jlist defaultlistmodel. if have created categories , choose save project , continue other time, when load saved file loads perfect except categorylist. it's still blank, , if have project categories , load new project old categories still there.. can't figure out whats wrong, i've must have missed update here?

package test;  import javax.swing.*; import javax.swing.event.listselectionevent; import javax.swing.event.listselectionlistener; import javax.swing.filechooser.filenameextensionfilter;  import java.awt.*; import java.util.list; import java.awt.event.*; import java.io.*; import java.io.file; import java.util.*;    public class testar extends jframe {       jcombobox place;  jtextfield searchfield; jbutton searchbutton, hidebutton, deleteplacebutton, whatishere, hidecat, newcat, delcat; jfilechooser jfc = new jfilechooser("."); boolean changed = false;  defaultlistmodel<placecategory> datamodel = new defaultlistmodel<>(); jlist<placecategory> categorylist = new jlist<placecategory>(datamodel);  //  defaultlistmodel<placecategory> newdatamodel = new defaultlistmodel<>();  testar(){     super("test");      //filemenu  topp     jmenubar filebar = new jmenubar();     setjmenubar(filebar);      jmenu archive = new jmenu("file");     filebar.add(archive);      jmenuitem open = new jmenuitem("open");     archive.add(open);     open.addactionlistener(new openlis());      jmenuitem save = new jmenuitem("save");     archive.add(save);     save.addactionlistener(new savelis());      //kategorier Öst      jpanel east = new jpanel();     add(east, borderlayout.center);      east.add(new jlabel("categories"));       categorylist.setvisiblerowcount(3);     categorylist.setfixedcellwidth(50);     east.add(new jscrollpane(categorylist));     categorylist.setselectionmode(listselectionmodel.single_selection);      //actionlistener      hidecat = new jbutton("hide category");     east.add(hidecat);      newcat = new jbutton("new category");     east.add(newcat);     newcat.addactionlistener(new newcatlis());      delcat = new jbutton("delete category");     east.add(delcat);      boxlayout eastlayout = new boxlayout(east, boxlayout.y_axis);     east.setlayout(eastlayout);      setdefaultcloseoperation(exit_on_close);      setsize(300,300);     setvisible(true);     setlocationrelativeto(null);     setresizable(false); }   class newcatlis implements actionlistener{     public void actionperformed(actionevent ave){         string categoryname;         color color = color.black;          categoryname = joptionpane.showinputdialog(testar.this, "name on category");         color = jcolorchooser.showdialog(testar.this,"chooser color", color);         placecategory pc = new placecategory(categoryname, color);         datamodel.addelement(pc);      }  }  class openlis implements actionlistener{     public void actionperformed(actionevent ave){         int answer = jfc.showsavedialog(testar.this);         if(answer != jfilechooser.approve_option){             return;         }          file file = jfc.getselectedfile();         string filename = file.getabsolutepath();          try{              fileinputstream fis = new fileinputstream(filename);             objectinputstream ois = new objectinputstream(fis);              datamodel = (defaultlistmodel)ois.readobject();              system.out.println(datamodel);  //              newdatamodel = datamodel; //               //              datamodel.clear(); //               //              for(int i=0; < newdatamodel.size(); i++){ //                  placecategory pc = newdatamodel.get(i);  //                  datamodel.addelement(pc); //                  system.out.println("addar"); //              } //               //              newdatamodel.clear();               ois.close();             fis.close();             pack();             validate();             repaint();             changed = false;          } catch(classnotfoundexception e){             joptionpane.showmessagedialog(testar.this, "something went wrong... "+e.getmessage());         } catch(filenotfoundexception e){             joptionpane.showmessagedialog(testar.this, "can not open file...");         } catch(ioexception e){             joptionpane.showmessagedialog(testar.this, "something went wrong... "+e.getmessage());         }     } }  class savelis implements actionlistener{     public void actionperformed(actionevent ave){         int answer = jfc.showsavedialog(testar.this);         if(answer != jfilechooser.approve_option){             return;         }          file file = jfc.getselectedfile();         string filename = file.getabsolutepath();          try{             fileoutputstream fos = new fileoutputstream(filename);             objectoutputstream oos = new objectoutputstream(fos);              oos.writeobject(datamodel);              oos.close();             fos.close();              changed = false;          } catch(filenotfoundexception e){             joptionpane.showmessagedialog(testar.this, "can not open file...");         } catch(ioexception e){             joptionpane.showmessagedialog(testar.this, "something went wrong... "+e.getmessage());         }     } }  public static void main(string[] args){     new testar(); }  } 

and placecategory ofc!

package test;   import java.awt.*; import java.io.*;  public class placecategory implements serializable {  private string name; public color color;    public placecategory(string name, color color){     this.name = name;     this.color = color;   }  public string tostring(){     return name; }  public color getcolor() {      return color; }  public string getname(){     return name; }   } 

found way make happen! added after load:

categorylist.setmodel(datamodel);