Setting @Value annotation with default variable

Question

Is it possible to use @Value annotation with a variable as default?

I have a variable processingYear , I would like to read from properties, If it cannot read from properties, I would like to assign the current year into the variable.

@Value("${processing_year:2021}")
int processingYear;

With the code specific above, I can read the processingYear from the properties file, and assign value to it, if reading from properties failed, the variable will be set to 2021.

However, I do not see a way to assign the current year as a default variable currentYear. Following is what I imagined and would like to see if there is anything to assign a default variable to it.

    LocalDate date = LocalDate.now();
    Locale locale = Locale.US;

    int currentYear = Integer.parseInt(date.format(DateTimeFormatter.ofPattern("yyyy",locale)));

    @Value("${process_year:currentYear}")
    int processingYear;

Boris Chistov · Accepted Answer · 2021-02-26 09:50:15Z

1

Well you can do it with @Value

Just try this:

@Value("${currentYear:#{(T(java.time.Year).now().getValue())}}")
private int year;

answered Feb 26, 2021 at 9:50

Boris Chistov

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1 Comment

Poon JP Over a year ago

How about if I want to set private String month; to "Feb" ?

Gautham M · Accepted Answer · 2021-02-26 09:05:43Z

0

Yes you can provide as below :

@Value("${processing_year:5}")
int processingYear;

Provide the default value after :. This would assign a default value of 5 to processingYear

If you want to provide other values then you need to prefix with #:

@Value("$someObj.value:#{null}}")
Object someObj;

@Value("#{'${someObject.stringlist:}'.split(',')}")
Collection<String> strings;

If you need to set a variable, then you need to use @Value along with a setter method:

int processingYear;

@Value("${process_year:-1}")
private void setProcessingYear(int year) {
    if(year == -1) {
        // -1 used to identify that no value was passed. so in this case we use currentyear.
        year = currentyear;
    }
    processingYear = year;
}

edited Feb 26, 2021 at 9:05

answered Feb 26, 2021 at 7:51

Gautham M

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7 Comments

Poon JP Over a year ago

Thank you @Gautham, I have tried, but with the following error message

Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1008E: Property or field 'currentYear' cannot be found on object of type 'org.springframework.beans.factory.config.BeanExpressionContext' - maybe not public or not valid?

Poon JP Over a year ago

field currentYear is already public, and both currentYear and processingYear are global variables.

Gautham M Over a year ago

@PoonJP I have updated my answer. In your case, you need to use a setter method and @Value

Poon JP Over a year ago

Thanks. I have something like that before, but I would like to see if there is anything I can simplify using the @value annotation.

Gautham M Over a year ago

Not sure if it is possible to do that directly with the field. Using a setter might be the best option as you could easily debug to analyze any issues

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