Grails Error Handling With Custom Http Status Code

First need to create a trait Groovy file as follows under src/groovy:

trait CustomExceptionHandler {
    /* Handle common exception */
    def handleException(Exception e) {
        handleCustomException(new CustomException(e.getMessage()))
    }

    /* Handle defined custom exception */
    def handleCustomException2(CustomException2 e) {
        handleCustomException(e)
    }

    /* Handle defined custom exception */
    def handleCustomException(CustomException e) {
        if (!CommonUtils.request) {
            // do something
        }
        else {
            CommonUtils.currentResponse.status = 220 (Custom response code)
            if(e.getStatusCode()) {
                CommonUtils.currentResponse.status = e.getStatusCode()
            }
            if (CommonUtils.request.xhr) {
                def error = [
                        type: "error",
                        message: e.getMessage()
                ]
                render error as JSON
            }
            else {
                render(view: "/error/error", model: [exception: e])
            }
        }
    }
}

Create a groovy class under src/groovy:

import org.springframework.web.context.request.RequestContextHolder
class CommonUtils {
    public static def getRequest() {
        def request = RequestContextHolder.getRequestAttributes()
        return request ? request.request : null
    }

    public static HttpServletResponse getCurrentResponse() {
        return WebUtils.retrieveGrailsWebRequest().getCurrentResponse()
    }
}

Exception Types (Reside in src/groovy):

class CustomException extends RuntimeException {

}
class CustomException2 extends CustomException {

}

How controller can use this feature:

class Controller1 implements CustomExceptionHandler {
    def index() {
        throw new Exception("Common exception")
    }

    def index2() {
        throw new CustomException("Defined custom exception")
    }

    def index3() {
        someService.index3()
    }

    def index4() {
        someService.index4()
    }
}

Exception thrown from service bahave same as from controller

class SomeService {
    def index3() {
        throw new Exception("Common exception")
    }

    def index4() {
        throw new CustomException("Defined custom exception")
    }
}

Java Code To Check Repeated Character In String

import java.util.regex.Pattern;
import java.util.regex.Matcher;

class RepeatedCharacterCheck {
    public static void main (String[] args) throws java.lang.Exception {
        String stringToMatch = "abccdeeefenonn";
        Pattern p = Pattern.compile("(\\w)\\1+");
        Matcher m = p.matcher(stringToMatch);
        while (m.find()) {
            System.out.println("Duplicate character " + m.group(0));
        }
    }
}

Output

Duplicate character cc
Duplicate character eee
Duplicate character nn