Theory:

The future perfect tense comes next after the future simple and future continuous.
The future perfect is a verb form or construction used to describe an event that is expected or planned to happen before a time of reference in the future.
In simple words, it refers to an action that will be completed by a certain time in the future.
Example:
1. He will have finished his homework by 9 pm.
2. I will have left for work by morning.
3. Hari will not have eaten by now.
The auxiliary verb used in the case of the future perfect tense is "will have". The main verb takes the tense form of "past participle".
Past participle means the verb that typically expresses a completed action. A list of commonly used past participle forms of verbs is given below:
 
Infinitive
Past Participle 
be
been
begin
begun
bite 
bitten
break 
broken
buy 
bought
choose 
chosen
come 
come
do 
done
drink 
drunk
eat 
eaten
fall 
fallen
feel 
felt
find 
found
get 
got
go 
gone
grow 
grown
have 
had
hide 
hidden
keep 
kept
know 
known
lead 
led
leave 
left
lie 
lain
lose 
lost
make 
made
meet 
met
put 
put
read
read
ride 
ridden
ring 
rung
rise 
risen
run 
run
say 
said
see 
seen
sell 
sold
set 
set
sing 
sung
sit 
sat
stand 
stood
take
 taken
teach 
taught
think 
thought
wake 
woken
 
Formation of future perfect tense sentences:
Subject + will have + past participle + rest of the sentence (time reference/adj/adv/noun etc.)
He + will have + finished + his dinner by now.
It + will have + stopped + raining by then.
They + will have + woken + up their whole neighbourhood.
Negative sentence formation :
Subject + will "not" have + past participle + rest of the sentence (time reference/adj/adv/noun etc.)
She + will not have + taught + these portions.
The rain + will not have + stopped + by then.
They + will not have + left + their house.
Question formation:
Will + subject + have (+not) + past participle + rest of the sentence (time reference/adj/adv/noun etc.)
Will + they + have + sung + the carols yet?
Will + she + have not + gone + to school?