What are restrictions using strictfp in an interface?

The strictfp modifier can be used in an interface declaration. The effect of the strictfp modifier is to make all float or double expressions within the interface declaration be explicitly FP-strict.

strictfp interface MyInterface {
   void method();
}

But a method declared in an interface must not be declared strictfp or native or synchronized, or a compile-time error occurs, because those keywords describe implementation properties rather than interface properties.

interface MyInterface {
   strictfp void method(); //compiler error 
}

However, a method declared in an interface may be implemented by a method that is declared strictfp or native or synchronized in a class that implements the interface.