Posts in "Core Java"

String Builder

A String Builder is like a String but can be modified. String has the drawback that once created it can not be modified. To overcome that problem String Buffer and String builder can be used. Difference between String Buffer and String Builder ‘StringBuffer’ is safe for use by multiple threads(Thread Safe). The methods are synchronized…. Continue reading

Serialization in Java

Java object serialization is used to persist Java objects to a file, database, network, process or any other system. Serialization flattens objects into an ordered, or serialized stream of bytes. The ordered stream of bytes can then be read at a later time, or in another environment, to recreate the original objects.

Constructor in Java

Constructors in Java can be seen as a special method in a class. But there is a big difference between Constructor and Method. These differences can be defined in terms of purpose,  syntax, and invocation. A constructor is used in the creation of an object of a class.

Inner Class

Java Inner classes are classes within class. An inner class instance has a special relationship with outer class. This special relationship gives inner class access to a member of the outer class as if they are the part of the outer class. Note: Java Inner class instance has access to all member of the outer… Continue reading


Java Inheritance defines an is-a relationship between a superclass and its subclasses. This means that an Object of a subclass can be used wherever an object of the superclass can be used. Class Inheritance in Java is used to build new Classes from existing Classes. The inheritance relationship is transitive: if Class x extends Class… Continue reading

Java Method Override

A class inheriting the method from its superclass has the option to override it. The benefit of overriding is the ability to define behavior specific to a particular class. In the case of a concrete subclass, it is forced to implement all methods defined in abstract class if no other superclass implemented it in the hierarchy. Overriding sometimes referred… Continue reading

Java Exceptions Tutorial

Exception in Java is used to handle errors or any other exceptional event that occurs in the normal flow of a program. There are several way Exception can occur in Java. Data provided is not in expected format(eg. int instead of String). DB cannot be connected. Network connection Lost. An object is null. …..

Collection in Java

Collection Framework has been added in JDK 1.2 and has been expanded in 1.4 -1.6 Interface & Classes of Collection Framework Collection API provides a group of the interface to choose from, but it also gives you some concrete classes to directly play with. Core Interfaces Collection List Set SortedSet (Extends Set Interface) NavigableSet (Extends SortedSet) Map… Continue reading

Interface in java

Defining a Contract means to create an Interface. This Contract states what a Class can do without forcing how it should do it. In this Java Interface Tutorial, we will talk about Interfaces. How to create one and rules applied to Interfaces.