Difference between Vector and ArrayList in java:

java.util.Vector came along with the first version of java development kit (JDK). java.util.ArrayList was introduced in java version1.2, as part of java collections framework. As per java API, in Java 2 platform v1.2,vector has been retrofitted to implement List and vector also became a part of java collection framework.
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. Difference is in the way they are internally resized. By default, Vector doubles the size of its array when its size is increased. But, 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.
Vector or ArrayList? Which is better to use in java?
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.
Is there an alternate available in java for Vector?
ArrayList can be synchronized using the java collections framework utility class and then ArrayList itself can be used in place of Vector.
When there is no need for synchronized operation and you still look for better performance ‘Array’ can be used instead of ArrayList. But the development is tedious, since it doesn’t provide user friendly methods.
When you use Vector or ArrayList, always initialize to the largest capacity that the java program will need. Since incrementing the size is a costlier operation.


  1. Good differences Maddy, I have also shared few on my blog Arraylist vs Vector in Java, let me know how do you find it.

  2. If you are in need of a thread-safe list then you can use CopyOnWriteArrayList or synchronized ArrayList in Java, its better option because vector is no longer maintained.


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