code: public void exportEmitter() {
  		if (selected == null) {
  			return;
  		}
  
  		chooser.setDialogTitle("Save");
  		int resp = chooser.showSaveDialog(this);
  		if (resp == JFileChooser.APPROVE_OPTION) {
  			File file = chooser.getSelectedFile();
  			if (!file.getName().endsWith(".xml")) {
  				file = new File(file.getAbsolutePath()+".xml");
  			}
  			
  			try {
  				ParticleIO.saveEmitter(file, selected);
  			} catch (IOException e) {
  				Log.error(e);
  				JOptionPane.showMessageDialog(this, e.getMessage());
  			}
  		}
  	}
docs: Export an emitter XML file