Question

All of the methods in an interface are both _______ (no need to explicitly include these keywords, however)

a. Public and static
b. Private and final
c. Abstract and static
d. Public and abstract

Answer 1

All methods in an interface are public and abstract by default; this defines a contract for implementing classes without dictating how the methods are executed.

Step-by-step explanation:

All of the methods in an interface are by definition public and abstract. This means that every method is implicitly public and abstract whether or not these keywords are explicitly mentioned in the interface's definition. The correct answer to the question is (d). Public and abstract. In Java, an interface is a reference type that is similar to a class and is a collection of abstract methods. A class 'implements' an interface, thereby inheriting the abstract methods of the interface. Additionally, as of Java 8, interfaces can contain default and static methods which are not abstract.

Interfaces are often used to achieve abstraction in Java. By providing methods without their implementations, they set a contract for the implementing classes to follow, ensuring that those classes adhere to a specific interface of methods. This allows for a high level of abstraction within code design.