I implemented this plugin some time ago and now finally found time to update it to support Netbeans 8.2.
This open-source software provides a simple tool which helps develeopers to write and debug regular expressions. It is using the Java Regex API, so the results are directly comparable to those in your applications.
You can install the plugin through the Netbeans Plugin Portal Update Center (Tools > Plugins), download it from Github1 or from the Netbeans Plugin Portal2. Afterwards you’ll see a new Menu Entry in Window saying Regex Tester.
In the main window you can set your regular expression, replacements and an input string. Each change is evaluated live, so there is no need to press enter or some button.
Any errors are displayed on the right site, the lower parts shows the result of the regex evaluation.
Java supports 9 different flags for regular expressions which can be configured in the second tab.