Cannot cast service in JSP

[aliaksandr_hvozdzeu]

Hello, community.

I'm trying to change the standard error handler along the path /libs/sling/servlet/errorhandler.

I also created a service and an implementation for it to use the configuration.

In default.jsp I added import com.custom.aem.common.errorhandler.CustomErrorHandlerService

<%@page session="false" pageEncoding="utf-8"
        import="com.day.cq.wcm.api.WCMMode,
                    java.io.PrintWriter,
                    org.apache.sling.api.SlingConstants,
                    org.apache.sling.settings.SlingSettingsService,
                    org.apache.sling.api.request.RequestProgressTracker,
                    org.apache.sling.api.request.ResponseUtil,
                    org.apache.commons.lang3.StringEscapeUtils,
                    com.custom.aem.common.errorhandler.CustomErrorHandlerService" %>
<%@taglib prefix="sling" uri="http://sling.apache.org/taglibs/sling/1.0" %>
<sling:defineObjects />

And trying to get properties from config by service in JSP.

<%
    String message = (String) request.getAttribute("javax.servlet.error.message");
    Integer scObject = (Integer) request.getAttribute("javax.servlet.error.status_code");
    boolean isAuthorMode = WCMMode.fromRequest(request) != WCMMode.DISABLED && !sling.getService(SlingSettingsService.class).getRunModes().contains("publish");

    int statusCode = (scObject != null)
            ? scObject.intValue()
            : HttpServletResponse.SC_INTERNAL_SERVER_ERROR;
    if (message == null) {
        message = statusToString(statusCode);
    }
    response.setStatus(statusCode);
    response.setContentType("text/html");
    response.setCharacterEncoding("utf-8");

    CustomErrorHandlerService customErrorHandlerService = sling.getService(CustomErrorHandlerService.class);
    String[] sites = customErrorHandlerService.getSites();
    String externalErrorPage = customErrorHandlerService.getExternalErrorPage();
    String requestSite = request.getRequestURL().toString();
    boolean isSiteCatchError = isSiteContains(sites, requestSite);

%>

but faced issue 

Caused by: java.lang.ClassCastException: com.custom.aem.common.errorhandler.CustomErrorHandlerServiceImpl cannot be cast to com.custom.aem.common.errorhandler.CustomErrorHandlerService
	at org.apache.jsp.apps.sling.servlet.errorhandler.default_jsp._jspService(default_jsp.java:408)
	at org.apache.sling.scripting.jsp.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
	at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:502)
	... 84 common frames omitted

Service

public interface CustomErrorHandlerService {

    String[] getSites();
    String getExternalErrorPage();

}

Implementation

(service = CustomErrorHandlerService.class, immediate = true)
@Designate(ocd = CustomErrorHandlerServiceImpl.Config.class)
public class CustomErrorHandlerServiceImpl implements CustomErrorHandlerService {

    private static final Logger LOGGER = LoggerFactory.getLogger(CustomErrorHandlerServiceImpl.class);

    @ObjectClassDefinition(
            name = "Custom Error Page Handler Configuration",
            description = "This configuration reads the values to make an error page for sites"
    )
     Config {
        @AttributeDefinition(
                name = "Sites",
                description = "Sites for Handling Error Pages",
                type = AttributeType.STRING)
        String[] getSites();

        @AttributeDefinition(
                name = "External Error Page Url",
                description = "Link to external error page")
        String getExternalErrorPage();
    }

    private String[] sites;
    private String externalErrorPage;

    
    protected void activate(Config config) {
        this.sites = config.getSites();
        this.externalErrorPage = config.getExternalErrorPage();
    }

    
    protected void deactivate() {
        LOGGER.info("CustomErrorHandlerServiceImpl has been deactivated!");
    }

    
    public String[] getSites() {
        return sites;
    }

    
    public String getExternalErrorPage() {
        return externalErrorPage;
    }

}

 What am I doing wrong? Thanks in advance.

[Saravanan_Dharmaraj]

Are you missing @component annotation of top of the implementation class?

[aliaksandr_hvozdzeu]

Sorry, I missed in the message. I have annotation in class

@component(service = CustomErrorHandlerService.class, immediate = true)

[aliaksandr_hvozdzeu · Accepted solution]

Fixed. The reason was that 2 identical services were registered. After turning off (deleting) everything worked fine. Thanks to all.