code: public void importContext() {
  		JFileChooser chooser = new JFileChooser(Constant.getContextsDir());
  		File file = null;
  	    chooser.setFileFilter(new FileFilter() {
  	           @Override
  	           public boolean accept(File file) {
  	                if (file.isDirectory()) {
  	                    return true;
  	                } else if (file.isFile() && file.getName().endsWith(".context")) {
  	                    return true;
  	                }
  	                return false;
  	            }
  	           @Override
  	           public String getDescription() {
  	               return Constant.messages.getString("file.format.zap.context");
  	           }
  	    });
  	    
  	    int rc = chooser.showOpenDialog(View.getSingleton().getMainFrame());
  	    if(rc == JFileChooser.APPROVE_OPTION) {
  			try {
  	    		file = chooser.getSelectedFile();
  	    		if (file == null || ! file.exists()) {
  	    			return;
  	    		}
  	    		// Import the context
  				Model.getSingleton().getSession().importContext(file);
  				
  				// Show the dialog
  			    View.getSingleton().showSessionDialog(
  			    		Model.getSingleton().getSession(), 
  			    		Constant.messages.getString("context.list"), true);
  				
  			} catch (IllegalContextNameException e) {
  				String detailError;
  				if (e.getReason() == IllegalContextNameException.Reason.EMPTY_NAME) {
  					detailError = Constant.messages.getString("context.error.name.empty");
  				} else if (e.getReason() == IllegalContextNameException.Reason.DUPLICATED_NAME) {
  					detailError = Constant.messages.getString("context.error.name.duplicated");
  				} else {
  					detailError = Constant.messages.getString("context.error.name.unknown");
  				}
  				View.getSingleton().showWarningDialog(Constant.messages.getString("context.import.error", detailError));
  			} catch (Exception e1) {
  				log.error(e1.getMessage(), e1);
  				View.getSingleton().showWarningDialog(Constant.messages.getString("context.import.error", e1.getMessage()));
  			}
  	    }
  	}
docs: Prompt the user to export a context