Introduction We will see here an example on simple log4j configuration in Java. The purpose of inserting log statements into the code is a low-tech method for debugging it. It may also be the only way because debuggers are not always available or applicable. This is often the case for distributed applications.

Introduction Here you will see how ThreadLocal works in Java. Java ThreadLocal class is used to create thread-local variables. The thread-local variable can be read and written by the same thread only. In multi-threaded environments all threads of an Object share their variables, so if the variable is not thread safe, then an inconsistent state…

Table of Contents Introduction Prerequisites Reverse A String StringBuffer’s reverse() Method StringBuilder’s reverse() Method Writing Custom Method Using Recursion Using Java 8’s Lambda and Stream API Java main Class Testing String Reverse Source Code Introduction This tutorial will show you string reverse example in Java. You can use various ways to reverse a string in…

Introduction Here in this post I will discuss how singleton pattern works in Java. Singleton pattern is a design solution, where an application wants to have one and only one instance of a class, in all possible scenarios without any exceptional condition. The singleton instance is actually created per JVM but not across multiple JMVs….

Introduction HashMap (also known as HashTable) is a data structure that can map keys to values, used to implement an associative array. A HashMap uses a hash function to compute an index into an array of buckets or slots, from which the correct value can be found. Ideally, the hash function will assign each key…

Introduction Here I will discuss how to override equals() and hashCode() methods in Java. In Java language the important contract is whenever you override one of the methods (equals() and hashCode()), then you must override the other method. So it means that when you override method equals() then you must override hashCode() or vice versa.

Introduction RSA is a cryptosystem, which is known as one of the first practicable public-key cryptosystems and is widely used for secure data transmission. In such a cryptosystem, the encryption key is public and differs from the decryption key which is kept secret. In RSA, this asymmetry is based on the practical difficulty of factoring…

Introduction In this post we will see how to cache static resources like css, js and images for a specific period of time. So we will specify the time for how long we want to cache such static resources. Static resources like css, js images etc. need not be reloaded from the server every time…

Introduction This tutorial shows how to integrate Spring 3, Struts 2 and Hibernate 3 in the following example. In this example, Struts 2 will be used as a web framework and Spring 3 will be used as a core service. We will use ORM (Object Relational Mapping) framework Hibernate for our persistent layer to interact…