How to hide a text field

Do you install the iReport?

if yes,you can see the property "print when expression"  in the  property panel.

eg.you've got 2 text fields fieldA and fileldB.If you want to display the A only if the fieldB is not empty.

The print when expression in the Text A could be :F{filedB}!=null &&!"".equals(F{fieldB})