Question

I have the following lines in my code. I am validating captcha in a JSP form.
I don’t understand the meaning of all arguments passed in the FieldError object.

if (!reCaptchaResponse.isValid()) {
    FieldError fieldError = new FieldError("CaptchaObj", "captcha",
            uresponse, false, new String[] { "badCptcha.CaptchaObj.captcha" },
            null, "Please, Try Again ");
    result.addError(fieldError);
}

HERE result variable is of type BindingResult.

I want the exact meaning of each argument in the constructor of the FieldError object and especially for the code argument in the constructor which of type String.

Answer 1

I would suggest reading the API documentation for field error found here.

It mentions the following parameters for this constructor:

Parameters:
    objectName - the name of the affected object
    field - the affected field of the object
    rejectedValue - the rejected field value
    bindingFailure - whether this error represents a binding failure (like a type mismatch); else, it is a validation failure
    codes - the codes to be used to resolve this message
    arguments - the array of arguments to be used to resolve this message
    defaultMessage - the default message to be used to resolve this message

One of the most important parameters is the codes parameter, which contains a code that will be searched for within your message sources. If found the message matching this code will be displayed. Message sources can take arguments, so a Message Source can contain an entry like:

typeMismatch.startDate={0} is an invalid date. Use format DD/MM/YYYY.

In this case the code would be typeMismatch.startDate and the message corresponding with this code will display the first argument followed by the message. The {0} piece of the message indicates that it should display the first argument. These arguments are provided by the 6th parameter in the constructor, which in your example is null.