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Java Weekly, Issue 271
Here we go… 1. Spring and Java >> Use DataDog to monitor and troubleshoot your Java web applications Optimize performance with end-to-end tracing and out-of-the-box support for most Java...
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Guide to Stream.reduce()
1. Overview The Stream API provides a rich repertoire of intermediate, reduction, and terminal functions, which also support parallelization. More specifically, reduction stream operations allow us to...
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Introduction to the Null Object Pattern
1. Overview In this quick tutorial, we’ll have a look at the Null Object Pattern, a special case of the Strategy Pattern. We’ll describe its purpose and when we should actually consider using it. As...
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Combining JPA And/Or Criteria Predicates
1. Overview The JPA Criteria API can be used to easily add multiple AND/OR conditions when querying records in a database. In this tutorial, we’ll explore a quick example of JPA criteria queries that...
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An Introduction to Epsilon GC: A No-Op Experimental Garbage Collector
1. Introduction Java 11 introduced a No-Op Garbage Collector called Epsilon, which promises the lowest GC overhead possible. In this short tutorial, we’ll explore how Epsilon works, and we’ll mention...
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Filtering a Java Collection by a List
1. Overview Filtering a Collection by a List is a common business logic scenario. There are plenty of ways to achieve this. However, some may lead to under-performing solutions if not done properly. In...
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Adding a Copyright License Header for Java Source Files in IntelliJ IDEA
1. Overview In this tutorial, we’re going to look at how to add a license header to our IntelliJ IDEA project files. The license header typically describes a project file’s permitted usage and...
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Introduction to Spring Cloud OpenFeign
1. Overview In this tutorial, we’re going to describe Spring Cloud OpenFeign – a declarative REST client for Spring Boot apps. Feign makes writing web service clients easier with pluggable annotation...
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Delegation Pattern in Kotlin
1. Overview There are many use cases in which delegation is preferred to inheritance. Kotlin has great language-level support for this. In this tutorial, we’ll talk about Kotlin’s native support for...
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Guide to the JDBC ResultSet Interface
1. Overview The Java Database Connectivity (JDBC) API provides access to the database from a Java application. We can use JDBC to connect to any database as long as the supported JDBC driver is...
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Using the @Singular Annotation with Lombok Builders
1. Overview The Lombok library provides a great way of simplifying data objects. One of the key features of Project Lombok is the @Builder annotation, which automatically creates Builder classes for...
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Difference Between Stub, Mock, and Spy in the Spock Framework
1. Overview In this tutorial, we’re going to discuss the differences between Mock, Stub, and Spy in the Spock framework. We’ll illustrate what the framework offers in relation to interaction based...
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Eclipse Error: web.xml is missing and failOnMissingWebXml is set to true
1. Introduction In this tutorial, we’ll discuss the common Eclipse error, “web.xml is missing and <failOnMissingWebXml> is set to true“, that we get while creating a web application. 2. Eclipse...
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Serializing and Deserializing a List with Gson
1. Introduction In this tutorial, we’ll explore a few advanced serialization and deserialization cases for List using Google’s Gson library. 2. List of Objects One common use case is to serialize and...
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Building a Web Application with Spring Boot and Angular
1. Overview Spring Boot and Angular form a powerful tandem that works great for developing web applications with a minimal footprint. In this tutorial, we’ll use Spring Boot for implementing a RESTful...
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Resolving Failed to Configure a DataSource Error
1. Overview In this short tutorial, we’ll discuss what causes and what resolves the “Failed to configure a DataSource” error on a Spring Boot project. We’ll resolve the issue using two different...
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Guide to java.lang.ProcessBuilder API
1. Overview The Process API provides a powerful way to execute operating system commands in Java. However, it has several options that can make it cumbersome to work with. In this tutorial, we’ll take...
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Split a List into Parts in Kotlin
1. Introduction Let’s say we have an array like [a, b, c, d, e, f] and we want to split the elements up into separate groups, like [[a, b], [c, d], [e, f]] or [[a, b, c], [d], [e,f]]. In this tutorial,...
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Mapping Multiple JSON Fields to a Single Java Field
1. Overview In this tutorial, we’ll see how to use both Jackson and Gson to map different JSON fields onto a single Java field. 2. Maven Dependencies In order to use the Jackson and Gson libraries we...
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Spring Properties File Outside jar
1. Overview Property files are a common method that we can use to store project-specific information. Ideally, we should keep it external to the packaging to be able to make changes to the...
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