Skip to main content

Set Custom Status Codes and Error Messages in a Java Service

Overview​

WaveMaker Java Services let you take full control of API responses by returning custom HTTP status codes and meaningful error messages. This guide shows you how to use HttpServletResponse to set a status code and WMRuntimeException with MessageResource to throw structured error messages from your Java service.

Prerequisites​

Before you begin, make sure you have:

  • A WaveMaker project with at least one Java service created
  • Basic familiarity with Java and WaveMaker's Java service structure

Set a Custom HTTP Status Code​

Use HttpServletResponse to explicitly control the HTTP status code returned by your service method.

Import the Required Classes​

Add the following imports to your Java service file:

import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

Implementation​

Inject HttpServletRequest and HttpServletResponse as method parameters and call response.setStatus() with the desired code:

public String sampleJavaOperation(String name,
                                  HttpServletRequest request,
                                  HttpServletResponse response) {

    logger.info("Starting sample operation with request url "
                + request.getRequestURL().toString());

    // Set HTTP status code to 400 (Bad Request)
    response.setStatus(400);

    return null;
}
tip

Replace 400 with any valid HTTP status code that fits your use case — for example, 401 for unauthorized access, 422 for validation failures, or 200 for explicit success signaling.

Throw a Custom Error Message​

Use WMRuntimeException together with MessageResource to return structured, meaningful error messages when a request fails.

Import the Required Classes​

import com.wavemaker.commons.MessageResource;
import com.wavemaker.commons.WMRuntimeException;

Implementation​

Wrap your logic in a try-catch block and throw a WMRuntimeException with a MessageResource in the catch:

public User getUserById(Integer userId) {
    try {
        User user = userService.getById(userId);
        return user;

    } catch (Exception e) {
        throw new WMRuntimeException(
            MessageResource.create("MESSAGE_USER_NOT_FOUND")
        );
    }
}
note

MessageResource.create() accepts either a message key (e.g., "MESSAGE_USER_NOT_FOUND") or a plain string message. Using message keys is recommended when you want to support localization or centrally manage error strings.