Java Interview Guide : 200+ Interview Questions and Answers - Final method, variable and class

The video tutorial explains the use of the final modifier in Java. It covers how the final modifier can be applied to classes, methods, variables, and arguments. The final modifier on a class prevents subclassing, ensuring immutability and security. When applied to methods, it prevents overriding, maintaining core logic. For variables, it makes them constants, and for arguments, it prevents modification. Examples from the Java API, like the String and Integer classes, illustrate these concepts.

What is the effect of marking a class as final in Java?

• It allows the class to be subclassed.

• It prevents the class from being subclassed.

• It makes the class immutable.

• It allows the class to override methods.

Why are some classes like String and Integer marked as final?

• To allow them to be easily extended.

• To allow changes in hash code implementations.

• To ensure they remain mutable.

• To prevent security issues and maintain immutability.

What does marking a method as final prevent?

• The method from being overridden.

• The method from being executed.

• The method from being called.

• The method from being inherited.

What happens when a variable is declared as final?

• Its value cannot be changed once set.

• It can only be used in static methods.

• It cannot be used in calculations.

• Its value can be changed multiple times.

What is the purpose of marking an argument as final?

• To make it accessible only within the method.

• To allow it to be passed to other methods.

• To prevent its value from being modified within the method.

• To allow its value to be modified within the method.