strictfp doubt

[Kaarthick Ramamoorthy]

interface Perform
{
public strictfp abstract void add(double a, double b);
public strictfp abstract void sub(double a, double b);
}

why strictfp is not allowed here?.

[Barry Gaunt]

strictfp is an implementation detail, so it only allowed to be used in the classes that implement the interface. That is, you cannot force the implementor of your interface to use the strictfp feature.