Fail to Concat String with $V{PAGE_NUMBER}

Problem

I would like to concat String with $V{PAGE_NUMBER}

As I want to do preview in iReport, it show this error message in iReport console

Root Cause

Because of the Expression Class of $V{PAGE_NUMBER} is java.lang.Integer, so it will throw this error message.

Solution

Change the Expression Class of $V{PAGE_NUMBER} from java.lang.Integer java.lang.String, then the problem will be resolved.