public interface AQuestion { void someMethod(); } The class which implements AQuestion 1.Should have someMethod which must necessarily be public. 2.Should have someMethod which could be "friendly" or public 3.Should have someMethod which should not throw any checked exceptions. 4.Should have someMethod which cannot be sychronized as sychronized is not in the signature of the interface defination
Because all interface methods are inherently public, and you can't implement/override a method with a more restrictive access modifier (e.g., "friendly").