Take a look at the android tag. People generally post code snippets, and not their whole project (Android project tend to have many files). Only the original poster could adapt the code from the answers. No one else can. OP should test the code before accepting the answer.
If there are multiple answers, upvote the correct one. Downvote the wrong answer. There isn't more you can do.
It is however OP's job to only accept the answer when it's tested. I think it is a bad idea to only let high reputation users accept the answer, because:
- They will probably just approve it. They will trust OP has accepted the right answer.
- It will result in large queues. We already have problems controlling the close votes queue.
- The high reputation users don't know everything. If you throw a Haskell question at a C++ person; how would he know what the right answer is?
There are at this moment 5,552,433 question on Stackoverflow. 4,315,026 questions have answers with a score of 1 or more. Let's say 50% of these questions have an accepted answer; 2,157,513 answers will have to be (arguably unnecessary) reviewed.
It is a waste of time, because almost all accepted answers will be approved. Trust OP, or downvote/comment and move on. Only if an answer is dangerously wrong you'll need to flag it.