Discussing the future using the present perfect simple form

You can use the present perfect simple form to say that something will have happened by a certain time in the future.

"This time next year I will have finished my exams."

Discussing the future using the present perfect continuous form (also known as the future perfect continuous using will have been doing).

You can use the present perfect continuous form to say how long something will have been happening by a certain time in the future.

"This time next year I will have been teaching English for 15 years."