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Could Not Find or Load Main Class Error 1. Introduction Occasionally when we run a Java program, we might see “Could not find or load main class”. It’s easy to guess the reason: The JVM failed to find the main class and gave this error. But why couldn’t it? In… Continue Reading java-could-not-find-load-main-class
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Comparing getPath(), getAbsolutePath(), and getCanonicalPath() in Java 1. Overview The java.io.File class has three methods — getPath(), getAbsolutePath() and getCanonicalPath() — to obtain the filesystem path. In this article, we’ll have a quick look at the differences between them and discuss a use case where you may choose to use… Continue Reading java-path
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Array Processing with Apache Commons Lang 3 1. Overview The Apache Commons Lang 3 library provides support for manipulation of core classes of the Java APIs. This support includes methods for handling strings, numbers, dates, concurrency, object reflection and more. In this quick tutorial, we’ll focus on array processing with… Continue Reading array-processing-commons-lang
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Retrieving a Class Name in Java 1. Overview In this tutorial, we’ll learn about four ways to retrieve a class’s name from methods on the Class API: getSimpleName(), getName(), getTypeName() and getCanonicalName(). These methods can be confusing because of their similar names and their somewhat vague Javadocs. They also have some nuances when it… Continue Reading java-class-name
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Java 9 Platform Logging API 1. Introduction In this tutorial, we’ll explore the newly introduced Logging API in Java 9 and implement some examples to cover the most common cases. This API has been introduced in Java to provide a common mechanism to handle all the platform logs and to… Continue Reading java-9-logging-api
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What is the serialVersionUID? 1. Overview Simply put, the serialVersionUID is a unique identifier for Serializable classes. This is used during the deserialization of an object, to ensure that a loaded class is compatible with the serialized object. If no matching class is found, an InvalidClassException is thrown. 2. Example… Continue Reading java-serial-version-uid
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Java @SuppressWarnings Annotation 1. Overview In this quick tutorial, we’ll have a look at how to use the @SuppressWarnings annotation. 2. @SuppressWarnings Annotation Compiler warning messages are usually helpful. Sometimes warnings can get noisy, though. Especially when we can’t or don’t want to address them: public class Machine { private List… Continue Reading java-suppresswarnings
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Generic Constructors in Java 1. Overview We previously discussed the basics of Java Generics. In this tutorial, we’ll have a look at Generic Constructors in Java. A generic constructor is a constructor that has at least one parameter of a generic type. We’ll see that generic constructors don’t have to… Continue Reading java-generic-constructors
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Java Double Brace Initialization 1. Overview In this quick tutorial, we’ll show how double braces can be used for creating and initializing objects in a single Java expression. We’ll also look at why this technique can be considered an anti-pattern. 2. Standard Approach Normally we initialize and populate a set… Continue Reading java-double-brace-initialization
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Comparator and Comparable in Java 1. Introduction Comparisons in Java are quite easy – until they’re not. When working with custom types, or trying to compare objects that aren’t directly comparable, we need to make use of a comparison strategy. We can build one simply, but making use of the… Continue Reading java-comparator-comparable
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