How to use the jasper report scriptletClass

1. define the class extends to JRDefaultScriptlet
public class ReportScriptlet extends net.sf.jasperreports.engine.JRDefaultScriptlet
  // format of strDate: YYYY/MM/DD
public static String getFormatedDate(String strDate,String outputFormat){
try {
        // Some examples
        SimpleDateFormat formatter = new SimpleDateFormat(INPUT_DATE_FORMAT);
        Date date = (Date)formatter.parse(strDate.trim());
        formatter.applyPattern(outputFormat);
        String formatedDate = formatter.format(date);
        System.out.println("formatedDate:" + formatedDate);
return formatedDate;
    }catch (Exception e) {
    
     return strDate; // just don't format the String
    }
}
2. Added scriptletClass="tnReports.ReportScriptlet" in the report definition file(.jrxml)
3. Use the method defined in the class,e.g.
 $P{REPORT_SCRIPTLET}.getFormatedDate((String)$P{REPORT_SCRIPTLET}.getParameterValue("START_DATE"),"MMM dd, yyyy")