I will have painted my room in two hours and then we can go shopping.

[Alice Chu]

Please tell me if my understanding is correct.
1) I will have painted my room in two hours and then we can go shopping.
→ It means “painting” will be completed at any time in/within two hours.

2) I will paint my room in two hours, so I can’t go shopping with you.
→ It means “painting” will start at the end of two hours.

 

[5jj]

Please tell me if my understanding is correct.
1) I will have painted my room in two hours and then we can go shopping.
→ It means “painting” will be completed at any time in/within two hours.

2) I will paint my room in two hours, so I can’t go shopping with you.
→ It means “painting” will start at the end of two hours.

I1) could mean that the duration of the painting time will have been two hours. If that work starts one hour from now, then it will not be completed within the next two hours.

(2) It could mean that the duration of the painting time will be two hours. If that work starts now, you will be able to go shopping two hours from now.