I created the method just analogously to get() which also returns a boolean.

If you prefer the throwing solution I'll change it.
But we'd need to test the result of get(), too and then probably throw a PersistenceException

Could then look like this:
```
	/**
	 * save the selected TristateBoolean value (of a tristate checkbox)
	 * 
	 * @param field
	 *            the name of the field to be set
	 * @param newVal
	 *            the new state to save to the cb, one of TristateBoolean (TRUE/FALSE/UNDEF)
	 * @author H. Marlovits
	 */
	public void setTriStateBoolean(final String field, TristateBoolean newVal)
		throws IllegalArgumentException, PersistenceException{
		if (newVal == null)
			throw new IllegalArgumentException(
				"PersistentObject.setTriStateBoolean(): param newVal == null");
		String saveVal = "";
		if (newVal == TristateBoolean.TRUE)
			saveVal = StringConstants.ONE;
		if (newVal == TristateBoolean.FALSE)
			saveVal = StringConstants.ZERO;
		if (newVal == TristateBoolean.UNDEF)
			saveVal = StringConstants.EMPTY;
		boolean result = set(field, saveVal);
		if (result) {
			throw new PersistenceException(new ElexisStatus(Status.ERROR, CoreHub.PLUGIN_ID,
				ElexisStatus.CODE_NONE,
				"PersistentObject.setTriStateBoolean(): Error on saving value " + newVal
					+ " to field " + field, null));
		}
	}
```