Changing delimiter in @ConfigurationProperties for reading a List property

I have a list of values in one property in application.properties file:

my-property=abc,def,ghi

And I load it in my @ConfigurationProperties class:

@Configuration
@ConfigurationProperties
public class MyProperties {

    private List<String> myProperty;
}

But I don't know how to change delimiter (from comma to semicolon or other separator):

my-property=abc;def;ghi

---

I know I can write workaround, but I don't want to use them because:

• @Value for property, but it requires manually writing property name for each fields (loss of @ConfigurationProperties advantages).

@Value("#{'${my-property}'.split(';')}")
private List<String> myProperty;

• Many properties with index, but it requires manually indexing and it's arduous when there are a lot of them and you have to change the order:

my-property[0]=abc
my-property[1]=def
my-property[2]=ghi

• Writing getter with split, but I have to write getter for all properties manually:

private String myProperties;

public List<String> getMyProperty() {
    return Arrays.asList(myProperties.split(";"));
}

Basic usage

The answer is annotation @Delimiter.

You can set any string as delimiter (default value is ,). For example:

@Configuration
@ConfigurationProperties
public class MyProperties {

    @Delimiter(";")
    private List<String> myProperty;
}

and application.properties file:

my-property=abc;def;ghi

Longer strings

Longer string as delimiters also works. For example annotation @Delimiter("---") with property:

my-property=abc---def---ghi

How it works under the hood

If you interested, I found this annotation by debugging Spring source code. The key is class DelimitedStringToArrayConverter (check source code to find the annotation). You can see default value , when delimiter is null.

How it works:

• invoking setter of your property (you have to write it to set breakpoint for debugger):

    public void setMyProperty(List<String> myProperty) {
        this.myProperty = myProperty;
    }

• CollectionBinder
• IndexedElementsBinder
• BindConverter
• ApplicationConversionService
• DelimitedStringToArrayConverter