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Introduction to Apache Kylin
1. Introduction Apache Kylin is an open-source OLAP engine built to bring sub-second query performance to massive datasets. Originally developed by eBay and later donated to the Apache Software...
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Generate a Valid Expression From a String of Numbers to Get Target Number
1. Introduction In this tutorial, we’ll explore how to solve the problem of generating all valid expressions by inserting binary operators between the digits of a string. The resulting expression must...
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Thread per Connection vs Thread per Request
1. Introduction In this tutorial, we’ll compare two commonly used server threading models: thread-per-connection and thread-per-request. First, we’ll define exactly what we mean by “connection” and...
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Building an AI Chatbot in Java With Langchain4j and MongoDB Atlas
1. Overview Chatbot systems enhance the user experience by providing quick and intelligent responses, making interactions more efficient. In this tutorial, we’ll walk through the process of building a...
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A Guide to RestFB
1. Introduction RestFB allows us to interact programmatically with Facebook services, such as retrieving user profiles, posting to pages, and handling authentication. In this tutorial, we’ll explore...
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Guide to Eclipse OpenJ9 JVM
1. Overview OpenJ9 is a high-performance, scalable, and flexible Java Virtual Machine. We can use it as a replacement for HotSpot in many Java applications. IBM originally developed it as part of its...
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How to Map an Empty String to Null Using MapStruct
1. Overview In this tutorial, we’ll look at how to customize our MapStruct mappers to convert empty Strings into nulls. We’ll investigate several options, each offering varying levels of control and...
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Java Weekly, Issue 591
1. Spring and Java >> Writing Unit Tests With MockMvcTester: Returning a List as JSON [petrikainulainen.net] In this second post of his series on MockMvcTester, Petri Kainulainen demonstrates a...
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Serialization of Enum Values in Avro
1. Introduction Apache Avro is a data serialization framework that provides rich data structures and a compact, fast, binary data format. When working with Avro in Java applications, we often need to...
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Mastering Context in MapStruct: Leveraging @Context for Complex Source Mappings
1. Overview In this tutorial, we’ll discuss the @Context annotation in the MapStruct library, which helps populate target POJO attributes using external sources or services. Additionally, it can be...
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How to Fix Exception: Cannot Load Driver Class: com.mysql.jdbc.driver in...
1. Introduction When integrating MySQL with Spring Boot, we often rely on Spring Boot’s auto-configuration and JDBC support to connect to the database. However, it’s not uncommon to encounter...
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Java Weekly, Issue 592
1. Spring and Java >> Announcing Jipher: Java Cryptographic Service Provider for FIPS Environments [oracle.com] Oracle has released Oracle Jipher, a new Java Cryptographic Service Provider that...
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Determine if a File Is a PDF File in Java
1. Overview In this tutorial, we’ll explore several ways to determine whether a file is a PDF in Java, using an approach without third-party dependencies and with different libraries. 2. Detect by File...
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How to Fix H2 Console Not Showing in Browser With Spring Boot
1. Overview The H2 console serves as a Graphical User Interface (GUI) client for the H2 database, allowing us to query the database through a web page. However, we may encounter an issue where the...
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Printing Stack Values in Java
1. Overview Stack follows the Last In, First Out (LIFO) rule; printing its values correctly can sometimes be tricky. But don’t worry, we’ve got this covered! In this tutorial, we’ll explore different...
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Extracting Flat and Nested Keys from a JSONObject
1. Introduction When processing JSON, data in the JSONObject class – commonly provided by libraries like org.json – is a fundamental building block. A frequent requirement is to extract all the keys...
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Grouping Endpoints by Resources in Swagger
1. Introduction In this tutorial, we’ll explore the Swagger documenting feature in Java. Specifically, we’ll be focusing on how to organize our project’s APIs based on their URLs. There are several...
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Java Code Compilation Using Java Compiler API
1. Introduction In Java development, compilation is the first defense against syntax errors, type mismatches, and other issues that can derail a project. While traditional workflows rely on manual...
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How to Install NVM in a Docker Container
1. Overview Node Version Manager (NVM) is a tool for managing multiple Node.js versions on a machine. In this tutorial, we’ll learn how to install NVM in a Docker container. We’ll discuss three...
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Micrometer Observation and Spring Kafka
1. Overview In this tutorial, we’ll explore the monitoring capabilities provided by Spring Kafka using Micrometer and Spring Boot Actuator. We’ll start by looking at the native metrics exposed by...
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