Java Interface Quiz

Can a Java interface have variables?

• Yes, with a default value

• No, interfaces cannot have variables

• Yes, with a final keyword

• Yes, with a static keyword

Can a Java class implement multiple interfaces?

• No, Java classes can only implement one interface

• Yes, Java classes can implement multiple interfaces

• Only if the interfaces have the same method signature

• Only if the interfaces are marked as "extendable"

Which keyword is used to implement an interface in a Java class?

• use

• extends

• implements

• interface

Can methods in an interface have a method body?

• Yes, all methods in an interface must have a method body

• No, methods in an interface cannot have a method body

• Only final methods can have a method body in an interface

• Only default methods can have a method body in an interface

Which of the following is a correct statement about interfaces in Java?

• Interfaces can be instantiated directly

• Interfaces can have constructors

• Interfaces can extend multiple classes

• Interfaces can have abstract methods

What is the purpose of default methods in Java interfaces?

• To provide default implementation for methods

• To force classes to override the method

• To prevent inheritance from interfaces

• To make methods private

In Java, can an interface extend another interface?

• Yes, an interface can extend another interface

• No, an interface cannot extend another interface

• Only if the interfaces have the same method signature

• Only if the interfaces are marked as "extendable"

In Java, can an interface have private methods?

• Yes, interfaces can have private methods

• No, interfaces cannot have private methods

• Only if the interface is marked as "private"

• Only if the private methods are static

Which of the following is NOT a valid type of inheritance in Java?

• Single Inheritance

• Multiple Inheritance

• Hierarchical Inheritance

• Multi-level Inheritance

What is the output of the following Java code snippet? interface MyInterface {

void myMethod();

}

public class MyClass {

public static void main(String[] args) {

MyInterface obj = () -> System.out.println("Hello");

obj.myMethod();

}

}

• Error: Cannot invoke lambda expression

• Hello

• Compilation error

• Null