AEM 6.3 sling models implementation Error: cannot be correctly instantiated by the Use API?

[BigT168]

I try to write a class called Article.java.

if I do this

@Model(adaptables=Resource.class)

public class Article {

@Inject @Default(values="")

    private String title;

}

it works fine by retrieving from the article.html using <a data-sly-use.article="mycomponents.Article">

However, try to following the acs-aem sample code to implement an interface called Article, and another class called ArticleImpl as below

@Model(adaptables = SlingHttpServletRequest.class, adapters = Article.class, resourceType = ArticleImpl.RESOURCE_TYPE)

@Exporter(name = Constants.EXPORTER_NAME, extensions = Constants.EXPORTER_EXTENSION)

public class ArticleImpl implements Article {

    @ValueMapValue(optional = true, name = "title")

      private String title;

}

When trying to retrieve the title from article component, I am getting the error below

Java.lang.NoSuchMethodException: mycomponents.Article.<init>() (in this implementation, mycomponents.Article is an interface)

An InstatiationException issue.

I don't see the sample code to create a default constructor.

Please help.

Thanks.

[smacdonald2008]

See this article - it has an Sling Model example and shows how to display the value in a front end -- Developing your first Experience Manager 6.3 Components

[smacdonald2008]

We will release more Sling Model examples as well.

[Feike_Visser1]

Looking at your sample you are using SlingHttpServletRequest.class in your second example.

Can you compare your code with the core components? They are using this pattern too.

[BigT168]

I follow the core components as example.

However even the first example, I have to add below codes in the pom.xml to make it work

<Import-Package>

                            javax.inject;version=1,

                            javax.annotation;version=0.0.0.1_008_JavaSE,

                            <!-- JEE Servlet -->

                            javax.servlet,

                            javax.servlet.http,

                            <!-- Sling -->

                            org.apache.sling.api.resource;version=2.10.0,

                            org.apache.sling.models.annotations;version=1.4.0,

                            org.apache.sling.models.annotations.injectorspecific;version=1.1.0,

                            com.adobe.cq.sightly;version=3.1.0,

                            org.apache.commons.lang3; version=2.5,

                            !*

</Import-Package>

It doesn't look right, but it works for the first example.

Any ideas?

[Feike_Visser1 · Accepted solution]

I made an example too, can you check and compare?

htl-examples/TitleImpl.java at master · heervisscher/htl-examples · GitHub

[BigT168]

Thanks, working now.

I think the <import-package> lines, somehow messed up with the result. I removed the lines, now it works fine.

By the way, can you explain when to use

@Model(adaptables=Resource.class)   vs.

@Model(adaptables = SlingHttpServletRequest.class, adapters = Article.class, resourceType = ArticleImpl.RESOURCE_TYPE)

If my article component has an image, how to reuse the core image class (ImageImpl.java)? so I can pass the image path and return me a smart image class.

Do you have an example?

Thanks a lot.