java - read binary file and display content in Jlist -

how can read binary file , display in jpanel.up have initialized jframe,jpanel jbutton when run code button , frame appears when click show button need show data file here code have done.

    public class graphicaldisplay{         private jframe cframe;         private jbutton showbutton;         public graphicaldisplay() {          }      public void displaycompanylist() {         //creating frame display of contents , containers , other elements jlabel , jbutton         cframe = new jframe("list of companies");         cframe.setlocation(700,150);         cframe.setsize(600,300);          //creating button          showbutton =new jbutton("show list");          //create panel hold button         jpanel bpanel=new jpanel();         bpanel.add(showbutton);         //add panel frame         cframe.add(bpanel,borderlayout.center);         cframe.setvisible(true);          showbutton.addactionlistener(new actionlistener() {              @override             public void actionperformed(actionevent ae) {                   byte [] buffer =null;                  file a_file = new file("companies.dat");                  try                  {                  fileinputstream fis = new fileinputstream("companies.dat");                  int length = (int)a_file.length();                  buffer = new byte [length];                  fis.read(buffer);                  fis.close();                  }                  catch(ioexception e)                  {                  e.printstacktrace();                  }             }         });              } }