Access restriction on class due to restriction on required library rt.jar?

If you are getting an "access restriction" error on a class in your Java code, it means that you are trying to access a class or member (field or method) that has restricted access. This can happen if the class is part of a library (such as rt.jar) that is not included in your project's classpath, or if the class is part of the Java runtime itself and is not intended for public use.

To fix this error, you will need to either include the required library in your project's classpath, or modify your code to use a different class or method that is accessible.

If you are trying to access a class or member that is part of the Java runtime itself, you may need to use reflection to access it. Reflection allows you to access and manipulate class members that are not normally accessible at runtime. However, be aware that using reflection can be slower and more error-prone than using normal method calls, and should generally be avoided unless necessary.