Spring – how to use spring annotations like @Autowired or @Value in kotlin for primitive types

kotlinkotlin-interopkotlin-null-safetyspring

Autowiring a non-primitive with spring annotations like

@Autowired
lateinit var metaDataService: MetaDataService

works.

But this doesn't work:

@Value("\${cacheTimeSeconds}")
lateinit var cacheTimeSeconds: Int

with an error:

lateinit modifier is not allowed for primitive types.

How to autowire primitve properties into kotlin classes?

Best Answer

You can also use the @Value annotation within the constructor:

class Test(
    @Value("\${my.value}")
    private val myValue: Long
) {
        //...
  }

This has the benefit that your variable is final and none-nullable. I also prefer constructor injection. It can make testing easier.

Related Solutions

Java – the difference between @Inject and @Autowired in Spring Framework? Which one to use under what condition

Assuming here you're referring to the javax.inject.Inject annotation. @Inject is part of the Java CDI (Contexts and Dependency Injection) standard introduced in Java EE 6 (JSR-299), read more. Spring has chosen to support using the @Inject annotation synonymously with their own @Autowired annotation.

So, to answer your question, @Autowired is Spring's own annotation. @Inject is part of a Java technology called CDI that defines a standard for dependency injection similar to Spring. In a Spring application, the two annotations works the same way as Spring has decided to support some JSR-299 annotations in addition to their own.

C# – How to change the Page Title in ASP.Net 1.1

With ASP.Net 1.1, first you have to set the runat attribute on the title markup :

<title id="PageTitle" runat="server">WebForm1</title>

Then from the code behind :

// We need this name space to use HtmlGenericControl
using System.Web.UI.HtmlControls;

namespace TestWebApp
{

      public class WebForm1 : System.Web.UI.Page
      {
            // Variable declaration and instantiation
            protected HtmlGenericControl PageTitle = new HtmlGenericControl();

            private void Page_Load(object sender, System.EventArgs e)
            {
                  // Set new page title
                  PageTitle.InnerText = "New Page Title";
            }
      }
}

Imports System.Web.UI.HtmlControls

Namespace TestWebApp

    Public Class WebForm1
        Inherits System.Web.UI.Page

        Protected PageTitle As HtmlGenericControl = New HtmlGenericControl()

        Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

            PageTitle.InnerText = "New Page Title"
        End Sub

...

    End Class
End Namespace

Best Answer

Related Solutions

Java – the difference between @Inject and @Autowired in Spring Framework? Which one to use under what condition

C# – How to change the Page Title in ASP.Net 1.1

Related Topic