Textfield in table - how to access?

Hi all,
in my table I have some textfields generated via implementing TableFieldFactory and overriding the createField method.

My question now is, how can I access the field, e.g. to read the value a user has typed in, or remove the typed text?

In the table’s api I couldn’t find a proper solution.

The use case is:
With the fields another result table can be filtered (which already works perfectly), and on another button all filters shall be removed, means the value of the textfields shall be resetted (null / empty string).

Any ideas?