java question

1. what is error? what is exception?

2. String vs. StringBuffer vs. StringBuilder

3. final vs. finally vs. finalize

4. synchronized(a){

       synchronized(b){

}

    }

    any problems?

5. way to avoid GC

6. way to avoid dead lock

7. Collection<?> vs. Collection<Object>

8. Design pattern in java library? pattern in java IO ?