Is it possible to initialize an array in an interface using a "for" instruction?

Is it possible to initialize an array in an interface using a for instruction?

Simple question - Is it posible to initalize array in an interface?

Yes.

This works but i want to initialize array by "for" intsruction. Ok thanks for help

That's not a simple question ;)

You can't do this strictly because you can't add a static block to an interface. But you can have a nested class or enum.

IMHO, that could be more confusing than useful as follows:

public interface I {
    int[] values = Init.getValue();

    enum Init {;
        static int[] getValue() {
            int[] arr = new int[5];
            for(int i=0;i<arr.length;i++)
                arr[i] = i * i;
            return arr;
        }
    }
}

Java 8 allows static methods in interfaces, Java 9 also allows private methods, so we can avoid the nested class/enum using such a method:

public interface I {
    private static int[] getValues() {
        int[] arr = new int[5];
        for(int i=0;i<arr.length;i++)
            arr[i] = i * i;
        return arr;
    }
        
    int[] values = getValues();
}