@Override public int showOpenDialog(Component parent){
  File selFile;
  int result;
  m_DialogType=OPEN_DIALOG;
  initGUI(OPEN_DIALOG);
  result=super.showOpenDialog(parent);
  m_DialogType=UNHANDLED_DIALOG;
  removePropertyChangeListener(m_Listener);
  selFile=getSelectedFile();
  if ((result == APPROVE_OPTION) && (getFileMustExist()) && (selFile == null)) {
    result=showOpenDialog(parent);
  }
 else   if ((result == APPROVE_OPTION) && (getFileMustExist()) && (selFile != null)&& (selFile.isFile())&& (!selFile.exists())) {
    int retVal=JOptionPane.showConfirmDialog(parent,"The file '" + selFile + "' does not exist - please select again!");
    if (retVal == JOptionPane.OK_OPTION)     result=showOpenDialog(parent);
 else     result=CANCEL_OPTION;
  }
  if (result == APPROVE_OPTION) {
    if (getFileFilter() instanceof ExtensionFileFilter)     m_LastFilter=(ExtensionFileFilter)getFileFilter();
 else     m_LastFilter=null;
    if (getSelectedFile() != null)     configureCurrentHandlerHook(OPEN_DIALOG);
  }
  return result;
}

@ Override public int showOpenDialog ( Component parent ) { File selFile ; int result ; m_DialogType = OPEN_DIALOG ; initGUI ( OPEN_DIALOG ) ; result = super . showOpenDialog ( parent ) ; m_DialogType = UNHANDLED_DIALOG ; removePropertyChangeListener ( m_Listener ) ; selFile = getSelectedFile ( ) ; if ( ( result == APPROVE_OPTION ) && ( getFileMustExist ( ) ) && ( selFile == null ) ) { result = showOpenDialog ( parent ) ; } else if ( ( result == APPROVE_OPTION ) && ( getFileMustExist ( ) ) && ( selFile != null ) && ( selFile . isFile ( ) ) && ( ! selFile . exists ( ) ) ) { int retVal = JOptionPane . showConfirmDialog ( parent , "The file '" + selFile + "' does not exist - please select again!" ) ; if ( retVal == JOptionPane . OK_OPTION ) result = showOpenDialog ( parent ) ; else result = CANCEL_OPTION ; } if ( result == APPROVE_OPTION ) { if ( getFileFilter ( ) instanceof ExtensionFileFilter ) m_LastFilter = ( ExtensionFileFilter ) getFileFilter ( ) ; else m_LastFilter = null ; if ( getSelectedFile ( ) != null ) configureCurrentHandlerHook ( OPEN_DIALOG ) ; } return result ; }
pops up an " open file " file chooser dialog .
