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Immutable Objects in Java 1. Overview In this tutorial, we’ll learn what makes an object immutable, how to achieve immutability in Java, and what advantages come with doing so. 2. What’s an Immutable Object? An immutable object is an object whose internal state remains constant after it has been entirely… Continue Reading java-immutable-object
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Difference Between @NotNull, @NotEmpty, and @NotBlank Constraints in Bean Validation 1. Overview Bean Validation is a standard validation specification that allows us to easily validate domain objects by using a set of constraints declared in the form of annotations. While overall, the use of bean validation implementations such as Hibernate Validator… Continue Reading java-bean-validation-not-null-empty-blank
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Fifth Round of Improvements to the Reddit Application REST Spring 1. Overview Let’s continue moving forward the Reddit application from our ongoing case study. 2. Send Email Notifications on Post Comments Reddit is missing email notifications – plain and simple. What I’d like to see is – whenever someone comments… Continue Reading reddit-web-app-improvements-5
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Reading from a File in Kotlin 1. Overview In this quick tutorial, we’ll learn about the various ways of reading a file in Kotlin. We’ll cover both use cases of reading the entire file as a String, as well as reading it into a list of individual lines. Also obtaining… Continue Reading kotlin-read-file
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Working with Microsoft Excel in Java 1. Introduction In this tutorial, we will demonstrate the use of the Apache POI and JExcel APIs for working with Excel spreadsheets. Both libraries can be used to dynamically read, write and modify the content of an Excel spreadsheet and provide an effective way… Continue Reading java-microsoft-excel
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Save Data to a JSON File with Gson 1. Overview Gson is a Java library that allows us to convert Java Objects into a JSON representation. We can also use it the other way around, to convert a JSON string to an equivalent Java object. In this quick tutorial, we’ll… Continue Reading gson-save-file
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Spring Data REST Events with @RepositoryEventHandler 1. Introduction While working with an entity, the REST exporter handles operations for creating, saving, and deleting events. We can use an ApplicationListener to listen to these events and execute a function when the particular action is performed. Alternatively, we can use annotated handler which filters… Continue Reading spring-data-rest-events
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Basic and Digest Authentication for a REST Service with Spring Security Table of Contents * 1. Overview * 2. Configuration of Basic Authentication * 2.1. Satisfying the stateless constraint – getting rid of sessions * 3. Configuration of Digest Authentication * 4. Supporting both authentication protocols in the same RESTful… Continue Reading basic-and-digest-authentication-for-a-rest-api-with-spring-security
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Implementing a Simple Blockchain in Java 1. Overview In this tutorial, we’ll learn the basic concepts of blockchain technology. We’ll also implement a basic application in Java that focuses on the concepts. Further, we’ll discuss some advanced concepts and practical applications of this technology. 2. What is Blockchain? So, let’s… Continue Reading java-blockchain
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Memento Design Pattern in Java 1. Overview In this tutorial, we’ll learn what the Memento Design Pattern is and how to use it. First, we’ll go through a bit of theory. Then, we’ll create an example where we’ll illustrate the usage of the pattern. 2. What is the Memento Design… Continue Reading java-memento-design-pattern
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