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Java XPath NamespaceContext – NameSpace Resolution Example

In java example, we will learn xpath namespace resolution into an XML file using NamespaceContext which has namespace declarations and their usages.

Dropwizard – Failed to parse configuration [Could not resolve type id ‘http’ into a subtype]

This exception you may face while starting jetty server packaged inside your dropwizard REST application uber jar.

Converting OutputStream to InputStream

Learn to convert OutputStream to InputStream in Java using ByteArrayInputStream and Java NIO Files Channel API.

Dropwizard Authentication and Authorization

Learn to add username/password based authentication and role based authorization capabilities into REST APIs using basic authentication.

Python CSV Module: Read and Write CSV Files

Learn to work with CSV files in Python. Python language contains the csv module which has classes to read and write data in the CSV format.

Dropwizard Health Check Configuration Example

DropWizard health check is implemented by extending the HealthCheck class and returning Result.healthy() if everything is alright and Result.unhealthy() if something is not working – as expected.

Dropwizard Client Config for Jersey/HTTP Client

Dropwizard supports both Apache HttpClient and Jersey Client. Learn to inject client to the REST controller and inject custom properties.

Dropwizard Tutorial: Building a REST API with Example

In this step-by-step Dropwizard tutorial, learn to build a basic CRUD (Create, Read, Update, Delete) application having REST APIs to perform operations.

[Solved] Maven Shade Plugin – A required class was missing org/apache/commons/io/IOUtils

You may get this error when you have incompatible version of maven and it’s maven shade plugin. Fixing version number mismatch will solve the issue.

Creating Executable Fat Jar with Maven Shade Plugin

Learn to use the Maven Shade plugin for packaging a java application with its dependencies into a fat jar or uber jar.

Convert Maven Project to Gradle Project

The gradle init command generate a build.gradle file which you can now use to run all your builds using gradle commands.

How to Install Gradle Plugin in Eclipse

Gradle tutorial learn to import and install gradle plugin for eclipse either using eclipse marketplace and update manager.

Gradle Tutorial: Core Concepts and Installation

Learn about how Gradle is different from other build automation tools, and then we will see one simple example of installing and using Gradle.

Super CSV – Read and Write CSV Files in Java

Learn to read CSV file in Java and write data to CSV files. Super CSV file is opensource library to support read and write operations on CSV files.

Java Puzzle – Find Missing Number From Series

In this Java puzzle, we have a series of numbers and exactly one number is missing. We have to write a program to find the missing number.

Jasmine unit testing tutorial with examples

Jasmine tutorial to learn setup instructions, jasmine suite and specs, setup and teardown methods, describe blocks, jasmine matchers, jasmine spies etc.

Java Locale: A Comprehensive Guide

Learn about Localization and Internationalization with Locale. Learn to create Locale objects and use them for formatting dates and messages.

Java Unzip File with Sub-directories

Java examples of unzipping and extracting the zip file using java.util.zip package and apache commons compress module.

Get Current Working Directory in Java

To find the current working directory for any Java application, we can use System.getProperty(“user.dir”) or Paths.get().toAbsolutePath().

Serialize Java Object to XML using XMLEncoder

In this example, we will learn to serialize the java objects into XML files and then de-serialize them back to the original java objects.

Difference between Externalizable and Serializable in Java

Knowing the difference between Externalizable vs Serializable is important in two aspects, one – if could be asked as an interview question, two – you can use the knowledge to make better informed decision for performance improvement for applying serialization into your application.

Java Externalizable Example – More Efficient Serialization

You can achieve more efficient serialization by implementing Externalizable interface and overriding it’s methods writeExternal() and readExternal().

Generating Random Numbers in Java

Learn to use java.util.Random, Math.random(), SecureRandom and ThreadLocalRandom to generate random numbers based on your application requirements.

Java Classpath

Use given syntax examples for setting CLASSPATH for any java application runtime, in windows and linux environments.

Log4j2 HTMLLayout Configuration Example

This Log4j2 example will help you in configuring log4j2.xml file with HTMLLayout. The HTMLLayout generates an HTML page and adds each log statement to a row in a table.

Log4j2 ThreadContext – Fish Tagging

Log4j2 ThreadContext allows you to fish tag the log statements with multiple unique tags to analyze logs while diagnose a problem in runtime.

Log4j2 – Useful Log Format Pattern Layouts

Given log4j2 conversion patterns are for reference so that you and me don’t waste time to build these patterns everytime we are creating/editing log4j configuration files.

Configure Log4j2 for JUnit Tests

Learn some recommended ways to configure Log4j2 – specific to junit testcases and different from used in production.

Read a File from Resources Directory

Java examples of reading a file from the resources folder from a jar file, war file, spring application or the development environment.

Log4j2 JSON Configuration Example

Apache Log4j 2 is an upgrade to Log4j 1.x that provides significant improvements over its predecessor such as performance improvement, automatic reloading of modified configuration files, Java 8 lambda support and custom log levels. In addition to XML and properties files, Log4j2 can be configured using JSON also. 1. Log4j2 …

Log4j2 Properties File Example

Log4j2 properties tutorial. Learn to configure log4j2.properties file to output to console, rolling files etc. Learn log4j2 appenders, levels and patterns.

Log4j2 XML Configuration: Log4j2.xml Example

Learn log4j2 XML configuration example to configure console appender, rolling file appender and multiple appenders and bootstrapping Logger.

Spring mvc multiple file upload with progress bar in ajax and jquery

Spring mvc multiple file upload with progress bar example to upload multipart requests for files and save files to upload directory on server.

[Solved] java.lang.ClassNotFoundException: org.apache.commons.fileupload.FileItemFactory

I encountered this exception while building spring MVC file upload example. The error stacktrace looks like this: Solution You have incorrect version of apache commons-fileupload. To solve this error, you correct version 1.2.1. This will solve your error. Happy Learning !!

Spring MVC File Upload with CommonsMultipartResolver

Spring MVC file upload example. Learn to upload single or multiple files to a configured upload directory using CommonsMultipartResolver.

Spring MVC File Download Controller Example

In this Spring Boot MVC download file controller example, learn to create the handler method and prevent hot linking of the download URLs.

Top 10 Java Blogs and Websites

Over last 9 years, I have found these top 10 java websites most useful for me. I do not intend to rank them for their popularity, but how much useful they have been for me in my career.

Java OOP Concepts with Examples

In this Java OOPs concepts tutorial, we will learn four major object oriented principles– abstraction, encapsulation, inheritance, and polymorphism. They are also known as four pillars of the object oriented programming paradigm.

Java Programs to Calculate Factorial

We may be asked to write a program to calculate factorial during coding exercises in Java interviews. This always better to have an idea of how to build such a factorial program. 1. What is Factorial? The factorial of a number is the product of all positive descending integers up to …

JMS Point-To-Point Message Example

In JMS tutorial, you read about JMS messaging domains Point to Point Domain and Publish Subscribe Domain. In this example, we will go through one such example of point to point messaging domain. In point to point message the sender delivers the message to the queue and a single receiver …

Java JMS Publish-Subscribe Message Example

The publish/subscribe messaging domain is a one-to-many model in which a publisher sends a message through a topic to all active subscribers who receive it.

JMS Tutorial – Java Message Service Tutorial

Java Message Service is an API that supports the formal communication called messaging between computers on a network. JMS provides a common interface for standard message protocols and message services in support of the Java programs. JMS provides the facility to create, send and read messages. The JMS API reduces …

Producer Consumer Problem Using BlockingQueue

BlockingQueue is excellent when you want to skip the complexity involved in wait–notify statements. This BlockingQueue can be used to solve the producer-consumer problem as well as given blow example. As this problem is well known to every programmer, I am not going in detail of problem description. How BlockingQueue …

Iterate through a Collection in Java

Learn different techniques to iterate over a Java Collection (List, Set and Map) using for-loop, enhanced for-loop, Iterator and Java Stream.

Parse a String to Date in Java 8

Learn to convert a string to date in Java 8 using the new date time API classes such as LocalDate, LocalDateTime, ZonedDateTime and DateTimeFormatter. 1. Convert string to date in ISO8601 format By default, java dates are in ISO8601 format, so if you have any string which represents a date …

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