Java Collections API Interview Questions

1. You need to insert huge amount of objects and randomly delete them one by one. Which Collection data structure is best pet?
2. What goes wrong if the HashMap key has same hashCode value?
3. If hashCode() method is overridden but equals() is not, for the class ‘A’, then what may go wrong if you use this class as a key in HashMap?
4. How will you remove duplicate element from a List?
5. How will you synchronize a Collection class dynamically?

ANSWERS:

1. Obviously, LinkedList.
2. It leads to ‘Collision’ wherein all the values are stored in same bucket. Hence, the searching time increases quad radically.
3. Left to Readers.
4. Add the List elements to Set. Duplicates will be removed.
5. Use the utility method 
REference :http://excusemeworld.com/java-j2ee-interview-questions/java-collections-api-interview-questions/