Access restriction: The type 'Application' is not API (restriction on required library rt.jar)

Question

This happened to me as well, and the answers given here already were not satisfying, so I did my own research.

Background: Eclipse access restrictions

Eclipse has a mechanism called access restrictions to prevent you from accidentally using classes which Eclipse thinks are not part of the public API. Usually, Eclipse is right about that, in both senses: We usually do not want to use something which is not part of the public API. And Eclipse is usually right about what is and what isn't part of the public API.

Problem

Now, there can be situations, where you want to use public Non-API, like sun.misc (you shouldn't, unless you know what you're doing). And there can be situations, where Eclipse is not really right (that's what happened to me, I just wanted to use javax.smartcardio). In that case, we get this error in Eclipse.

Solution

The solution is to change the access restrictions.

• Go to the properties of your Java project,
  • i.e. by selecting "Properties" from the context menu of the project in the "Package Explorer".
• Go to "Java Build Path", tab "Libraries".
• Expand the library entry
• select
  • "Access rules",
  • "Edit..." and
  • "Add..." a "Resolution: Accessible" with a corresponding rule pattern. For me that was "javax/smartcardio/**", for you it might instead be "com/apple/eawt/**".

I was having the same problem. When I initially created the java project in Eclipse I specified JRE 8. When I went into the project's build path and edited the JRE System Library, the Java 8 execution environment was selected. When I chose to use an "Alernate JRE" (still java 8) it fixed the error for me.

Adding javafx accessible permission in eclipse oxygen go to project> properties> java build path> libraries> then expand the libraries and double click on> Access rules there you set the permission Resolution : Accessible Rule Pattern : javafx/**

To begin with (and unrelated), instantiating the Application class by yourself does not seem to be its intended use. From what one can read from its source, you are rather expected to use the static instance returned by getApplication().

Now let's get to the error Eclipse reports. I've ran into a similar issue recently: Access restriction: The method ... is not API (restriction on required project). I called the method in question as a method of an object which inherited that method from a super class. All I had to do was to add the package the super class was in to the packages imported by my plugin.

However, there is a lot of different causes for errors based on "restriction on required project/library". Similar to the problem described above, the type you are using might have dependencies to packages that are not exported by the library or might not be exported itself. In that case you can try to track down the missing packages and export them my yourself, as suggested here, or try Access Rules. Other possible scenarios include:

• Eclipse wants to keep you from using available packages that are not part of the public Java API (solution 1, 2)
• Dependencies are satisfied by multiple sources, versions are conflicting etc. (solution 1, 2, 3)
• Eclipse is using a JRE where a JDK is necessary (which might be the case here, from what your errors say; solution) or JRE/JDK version in project build path is not the right one

This ended up as more like a medley of restriction-related issues than an actual answer. But since restriction on required projects is such a versatile error to be reported, the perfect recipe is probably still to be found.