Java Interfaces Quiz

Which of the following is true about interfaces in Java?

• Interfaces can have instance variables

• Interfaces can have abstract methods

• Interfaces can be instantiated

• Interfaces cannot be implemented by classes

Which keyword is used by a class to implement an interface?

• extends

• implements

• imports

• package

Can an interface extend another interface in Java?

• Yes, using extends keyword

• Yes, using implements keyword

• No, interfaces cannot extend

• Only abstract classes can extend interfaces

Which of the following members can an interface have?

• Abstract methods

• Static methods

• Default methods

• All of the above

What is the default access modifier of methods in an interface?

• private

• public

• protected

• default (package-private)

Can an interface contain constructors?

• Yes

• No

• Only static constructors

• Only protected constructors

If a class implements multiple interfaces, it is called:

• Multilevel inheritance

• Multiple inheritance

• Hierarchical inheritance

• Hybrid inheritance

Which of the following is the correct way to declare an interface?

• class MyInterface {}

• interface MyInterface {}

• abstract interface MyInterface {}

• implements MyInterface {}

Can an interface contain static variables?

• Yes, and they are implicitly public static final

• Yes, but they are not final

• No

• Only if declared private

Can a class partially implement an interface?

• Yes, if the class is declared abstract

• Yes, in all cases

• No, it must implement all methods

• Only if it extends another class