Answer: Yes.

Here is an example which works well (see also Question 9 - Can an interface implement another).

   interface D { int b(); }
	
   interface C extends D { int a(); }
		
   class B implements C {
      public int a() { return 1; }
      public int b() { return 2; }
   }
				
   public class A {
      public static void main (String args[]) {
         B b = new B();
         System.out.println("OK: "+b.a()+" "+b.b());
      }
   }