private void addOkButtonEventHandler() {
		okButton.addActionListener (new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				File usersFile = new File(usersTextField.getText());
				if (!usersFile.exists())
				{
					showFileNotFoundError(usersTextField.getText());
					return;
				}
				
				File interestsFile = new File(interestsTextField.getText());
				if (!interestsFile.exists())
				{
					showFileNotFoundError(interestsTextField.getText());
					return;
				}
				
				File availabilitiesFile = new File(availabilitiesTextField.getText());
				if (!availabilitiesFile.exists())
				{
					showFileNotFoundError(availabilitiesTextField.getText());
					return;
				}
				
				try 
				{
					app.persistUserData(usersFile, interestsFile, availabilitiesFile);
				} 
				catch (Exception e1) 
				{
					e1.printStackTrace();
				}
				
				usersTextField.setText("");
				interestsTextField.setText("");
				availabilitiesTextField.setText("");
			}
		});
	}