Java Certification Question 0007

Which of the following statements are true?
1) An interface can only contain method and not variables
2) Interfaces cannot have constructors
3) A class may extend only one other class and implement only one interface
4) Interfaces are the Java approach to addressing its lack of multiple inheritance, but require implementing classes to create the functionality of the Interfaces.

Answer:
2) Interfaces cannot have constructors
If you try to create a constructor for an Interface the compiler will give you an error message something like "interface can't have constructors".
4) Interfaces are the Java approach to addressing the single inheritance model, but require implementing classes to create the functionality of the Interfaces.
An interface may contain variables as well as methods. However any variables are final by default and must be assigned values on creation. A class can only extend one other class (single inheritance) but may implement as many interfaces as you like (or is sensible).