Future perfect: will have (been, doing)

example situation:

Dave is an engineer. 

His job is to project and develop eolic solutions.

In January, he will have been working in the same company for 4 years.



The present perfect form will have + past participle is used to say something will already be achieved before a time in the future.

examples:
- They will be tired when they arrive. They will not have slept for a long time.
- You can call after midday The meeting will have finished by that time.

• as we can see from the examples above, the 'will have done, been, ..' to predict what we think has already happened at present:

        more examples:
        - Even if you hurry so much, by the time you'll get to the station the train will
        have left  already.
        - We are so late, the movie will have started by the time we get to the 
          cinema in the city. 


Now let's compare the future perfect with the future continuous:

- Simon is on holiday and he is spending his money very quickly. If he continues like this, he will have spent all his money before the end of next weekend.

- If you need to contact me, I'll be staying at the Generator Hostel until next Monday.