Interview

As the name suggests it is used for observing some objects.Observer watch for any change in state or property of subject.Suppose you are interested in particular object and want to get notified when its state changes then you observe that object and when any state or property change happens to that object,it get notified to […]

CodeProject One of the common interview question is “What are differences between Comparator and Comparable”. or “How will you sort collection of employee objects by its id or name”.For that we can use two interfaces.i.e. Comparator and Comparable.Before we actually see differences,let me give you brief introduction of both. Comparable interface: Class whose objects to […]

One of the common interview question is “What is difference between ArrayList and Vector”.Before we actually see differences,let me give you brief introduction of both. ArrayList ArrayList is implementation of list interface. ArrayList is not synchonized(so not thread safe) ArrayList is implemented using array as internal data structure.It can be dynamically resized . ArrayList increases […]

One of the common interview question is “What is difference between HashMap and HashSet”..Before we actually see differences,let me give you brief introduction of both. Java HashMap: HashMap in java How HashMap works in java hash and indexfor method in HashMap hashcode and equals method in java How to sort HashMap by keys and values […]

One of the common interview questions is “What are differences between Hashtable and HashMap“.When I started using them, I used any of them irrespective of their differences.Afterward I found noticeable differences between them which can affect your performance of the application. .Before we actually see differences, let me give you a brief introduction of both. […]