Difference between Vector and ArrayList in java?

• All the methods of Vector is synchronized. 

• But, the methods of ArrayList is not synchronized. All the new implementations of java collection framework is not synchronized.

• Vector and ArrayList both uses Array internally as data structure. 

• They are dynamically resizable. 

• Both ArrayList and Vector maintains the insertion order of element.

• Difference is in the way they are internally resized. 

• By default, Vector doubles the size of its array when its size is increased. 

• ArrayList increases by half of its size when its size is increased.

• Therefore as per Java API the only main difference is, Vector’s methods are synchronized and ArrayList’s methods are not synchronized.

• In general, executing a ‘synchronized’ method results in costlier performance than a unsynchronized method. Keeping the difference in mind, using Vector will incur a performance hit than the ArrayList. 

• But, when there is a certain need for thread-safe operation Vector needs to be used.