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Editorial Team
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Asked: 2026-06-10T19:08:44+00:00

I want to echo back the cache operation selected in the Request, so that

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I want to echo back the cache operation selected in the Request, so that it is displayed on the browser. I have very little JSP experience. How can I get the value of operation to appear?

JSP:

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<html>
    <body>
        <h1>Cache Operation Results - ${operation}</h1>
        <ul>
            <c:forEach items="${results}" var="nextObject">
                <pre>${nextObject.toString()}</pre>
            </c:forEach>
        </ul>
    </body>
</html>

Controller snippet: 

@RequestMapping(value = "/objectcache", method = RequestMethod.GET)
public ModelAndView objectCache(@RequestParam("operation") String operation, HttpServletRequest req) {

    List<String> cacheReturnValue = new ArrayList<String>();
    ModelAndView mav = new ModelAndView("/utils/objectCache", "results", cacheReturnValue);

    if (operation.equalsIgnoreCase("reload")) {
        cacheReturnValue = this.reloadCache();
    }

    mav.addObject("operation", operation);
    return new ModelAndView("/utils/objectCache", "results", cacheReturnValue);
}
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1 Answer

  1. Editorial Team

    The you have code should work properly after removing a bug – you’ve created ModelAndView twice and thus ignored “operation” added to first ModelAndView object. Solution – create mav only one time:

    @RequestMapping(value = "/objectcache", method = RequestMethod.GET)
public ModelAndView objectCache(@RequestParam("operation") String operation,
        HttpServletRequest req) {

    List<String> cacheReturnValue = new ArrayList<String>();

    if (operation.equalsIgnoreCase("reload")) {
        cacheReturnValue = this.reloadCache();
    }

    ModelAndView mav = new ModelAndView("/utils/objectCache");
    mav.addObject("results", cacheReturnValue);
    mav.addObject("operation", operation);
    return mav;
}

    EDIT:

    Small hint: since ModelAndView#addObject returns reference to this object, you can chain it’s calls without creating a variable mav like this:

    return new ModelAndView("/utils/objectCache")
        .addObject("results", cacheReturnValue)
        .addObject("operation", operation);
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