Posted in Core Java, Data Structure

Feature Comparison of some data structues

  ArrayList Array List Vector LinkedList HashTable HashMap Set Map
Unlimited size ×            
Index based            
Allow Nulls       ×    
Synchronized ×       ×    
Allow duplicate             ×  
Ordered data               ×
Posted in Core Java

Java – Abstract class vs Interface


Abstract class


Have abstract & non-abstract methods Only abstract methods
Not support multiple inheritance Supports multiple inheritance
Can have final/non-final/statis/non-static variables Only final & static variables
Can have:

·         static methods

·         main method

·         constructor

Cannot have




Can provide implementation of interface Cannot provide implementation of abstract class
When we want to add new methods When we want to have multiple inheritance
We extend it We implement it