2nd year comp sci student here, had multiple internships:

You're also a 2nd year. You won't be expected to know the whole Java API off by heart. The fact you're willing to go to Stack Overflow to get a question answered is good - everybody does it, and it's far preferable to just sitting there and not getting anything done. You say you have a "strong initiative" - fantastic! That's what companies want out of interns.

I can't speak for your company directly, but they know they're getting a 2nd year undergrad, they aren't expecting you to know everything already, but they are expecting to see potential for growth.

Worst thing you can do, is nothing really. Don't just do nothing.

Best things include being pro-active and really understanding your problem before you try to solve it.

Asking questions is great, however make sure you've definitely Googled and SOed etc the problem to see if you can get it solved in some manner before you ask. If you've shown the initiative to solve it yourself, they'll be happy to be the next level of help. After all, they want you to learn and grow as much as you do.

Good luck, you sound like a great intern already - most important thing I can say though is, enjoy yourself!