Spring @Value empty list as default

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Is there a way to set an empty list as default value for a property in Spring, something like:

@Value("${my.list.of.strings :" + new ArrayList<>() + "}")
private List<String> myList;

Obviously not new ArrayList, but I need an empty list there instead.

After taking a look at SpEL specification and combined with @javaguy's answer I came up with this:

@Value("${my.list.of.strings:}#{T(java.util.Collections).emptyList()}")
private List<String> myList;

Using Spring @Value with Defaults, Spring's @Value annotation provides a convenient way to inject property in this article – how to specify a default value for the @Value Spring annotation. We can also inject a comma-separated list of values into an array:. By Arvind Rai, April 17, 2019. Spring @Value annotation is used for expression-driven dependency injection. @Value can configure default value to be used when actual value is not available for dependency injection. @Value uses $ {} and # {} syntax to write expression. 1. $ {} is a property placeholder syntax.

You can use Collections.emptyList() to populate the empty list object with zero size as shown below:

@Value("#{T(java.util.Collections).emptyList()}")
private List<String> myList;

This will give you a zero sized myList

Spring @Value Default Value, Here is the syntax to inject property value into spring bean: To avoid this, @​Value annotation allows us to provide default value, the syntax is as shown below Git command to list conflicted files · Where is default localhost folder in Mac OSX  Let's look at the basic syntax for setting a default value for a String property: @Value("${some.key:my default value}") private String stringWithDefaultValue; If some.key cannot be resolved, then stringWithDefaultValue will be set to the default value of “my default value”. Similarly, we can set a zero-length String as the default value:

@Value("#{T(java.util.Arrays).asList('${my.list.of.strings:}')}")
private List<String> myList;

works for me, using Spring 5.0.x (gives empty list, if your my.list.of.strings property is not configured in context)

afterwards you can easily do something like

CollectionUtils.isNotEmpty(myList)

How to add default value to Spring Boot @Value annotation?, Using this method removes the need to cast the value of the expression to the By default SpEL uses the conversion service available in Spring core demo.list will now be a real collection of 4 entries // Each entry is a new empty String. In this tutorial, we will show you how to set a default value for @Value. 1. @Value Examples. To set a default value in Spring expression, use Elvis operator: #{expression?:default value} Few examples :

Actually, in the current Spring versions works just one symbol : with an empty defaultvalue.

The full example that I'm using:

@Value("${my.custom.prop.array:}")
private List<Integer> myList;

To be sure and safer I also adding init to the List variable:

@Value("${my.custom.prop.array:}")
private List<Integer> myList = new ArrayList<>();

8. Spring Expression Language (SpEL), In this tutorial, we will show you how to set a default value for @Value. 1. @Value Examples. To set a default value in Spring expression, use  To avoid this, @Value annotation allows us to provide default value, the syntax is as shown below: @Value("${property_name:default_value}") And the sample code is: In the below case, by default, 5 will be assinged to retryCount variable.

Spring @Value default value, In this case, Spring Boot will set the enabled field to the default value we defined the defaultSubject empty, we'll get a BindValidationException on startup: We can simply add a List field to our MailModuleProperties class:. To inject a default value you can pass it after property name, like so: @Value(“${owner:0}”). The problem is when you want to inject null as default value. If you try to use @Value(“${owner:null}”) then Spring will treat it literally and inject *”null”* string, which can lead to unexpected results!

Configuring a Spring Boot Module with @ConfigurationProperties, Collections.emptyList (Showing top 20 results out of 111,060) asList(1, 2); } }). origin: spring-projects/spring-framework Returns the value of the {@code Sec-​WebSocket-Key} header. * @return the value of The default layout for a windo. @Value annotation should be able to inject List<String> from YAML properties [SPR-11759] #16381 Closed spring-issuemaster opened this issue May 5, 2014 · 14 comments

java.util.Collections.emptyList java code examples, Empty default value is also supported, which results in an empty To inject a list or an array from a property you define the property's value  Default values can be provided for properties that might not be defined. In this example the value “some default” will be injected: @Value("${unknown.param:some default}") private String someDefault; If the same property is defined as a system property and in the properties file, then the system property would be applied.

Comments
  • Is private List<String> myList = new ArrayList<>() not enough?
  • my answer creates an empty list, if it helps, you can accept it
  • your answer is helpful but incomplete, since the value annotation points to a property in the first place (which should be initialized when not present - otherwise it leads to an IllegalArgumentException)
  • I have used that for zero sized list in my project and did not get any IllegalArgumentException
  • don't know about your code but mine breaks if I specify a property where there's no default value and does not come up in any property file
  • Seems it works, but no idea why. I would expect that empty list directly after colon and not after closing parenthesis }.