How to fix Optifine.jar (or any jar file) not opening or instantly crashing

If you're having trouble with any jar file not opening, even when you have java set as the default app, watch this video to manually open the file. This tutorial is tailored towards anyone having this problem towards optifine.

[@lynxnspark6768]

Wow what a helpful tutorial. Now i too can open my jar files 😃

[@kimberly-zf2uf]

Very informative video!

[@vikrambalaji4126]

thank you =)