Core Java interview

This is 1st part of java Serialization tutorial. Java Serialization Tutorial: Serialization in java Java Serialization interview questions and answers serialversionuid in java serializationexternalizable in java Transient keyword in java Difference between Serializable and Externalizable in Java Java provides mechanism called serialization to persists java objects in a form of ordered or sequence of bytes […]

CodeProjectTemplate method pattern is a behavioral design pattern which provide base method for algorithm,called template method which defers some of its steps to subclasses So algorithm structure is same but some of its steps can be redefined by subclasses according to context. Template means Preset format like HTML templates which has fixed preset format.Similarly in […]

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. […]