JavaWorld Core Java

• Packages and static imports in Java May 12, 2020
  In my previous Java 101 tutorial, you learned how to better organize your code by declaring reference types (also known as classes and interfaces) as members of other reference types and blocks. I also showed you how to use nesting to avoid name conflicts between nested reference types and top-level reference types that share the […]
• Nesting with Java interfaces February 20, 2020
  If you've read my Java 101 tutorial introducing static classes and inner classes, you should be familiar with the basics of working with nested classes in Java code. In this Java tip, you'll learn three common ways to use nesting techniques with Java interfaces. I'll also briefly demonstrate nesting interfaces with static methods, also known […]
• Static classes and inner classes in Java February 20, 2020
  Nested classes are classes that are declared as members of other classes or scopes. Nesting classes is one way to better organize your code. For example, say you have a non-nested class (also known as a top-level class) that stores objects in a resizable array, followed by an iterator class that returns each object. Rather […]
• Installing Oracle Java SE 11 on Ubuntu 18.04 January 21, 2020
  This article is a quick guide for Ubuntu Linux users installing Java 11, the current long-term support (LTS) Java version. I'll briefly make the case for migrating your code base to Java 11, then guide you through the steps to install Oracle JDK 11 using the Ubuntu command line.Note that this is a quick guide […]
• How to store data in Java objects January 20, 2020
  Last updated: January 2020Although the snooze button is probably the most commonly used button on an alarm clock, even a simple AlarmClock class needs a few more features. For instance, you might want to control how long the alarm clock will stay in snooze mode. In order to add such a feature, you need to […]
• What is the JDK? Introduction to the Java Development Kit January 17, 2020
  The Java Development Kit (JDK) is one of three core technology packages used in Java programming, along with the JVM (Java Virtual Machine) and the JRE (Java Runtime Environment). It's important to differentiate between these three technologies, as well as understanding how they're connected: The JVM is the Java platform component that executes programs. The […]
• What is the JRE? Introduction to the Java Runtime Environment January 17, 2020
  Together, the Java Development Kit (JDK), the Java Virtual Machine (JVM), and the Java Runtime Environment (JRE) form a powerful trifecta of Java platform components for developing and running Java applications. I've previously introduced the JDK and JVM. In this quick tutorial, you'll learn about the JRE, which is the runtime environment for Java.Practically speaking, a […]
• What is the JVM? Introducing the Java Virtual Machine January 17, 2020
  The Java Virtual Machine is a program whose purpose is to execute other programs. It's a simple idea that also stands as one of our greatest examples of coding kung fu. The JVM upset the status quo for its time, and continues to support programming innovation today.What the JVM is used for The JVM has […]
• Socket programming in Java: A tutorial January 8, 2020
  This tutorial is an introduction to socket programming in Java, starting with a simple client-server example demonstrating the basic features of Java I/O.  You'll be introduced to both the original java.io package and NIO, the non-blocking I/O (java.nio) APIs introduced in Java 1.4. Finally, you'll see an example that demonstrates Java networking as implemented from Java 7 […]
• Inheritance versus composition: How to choose January 8, 2020
  Inheritance and composition are two programming techniques developers use to establish relationships between classes and objects. Whereas inheritance derives one class from another, composition defines a class as the sum of its parts.Classes and objects created through inheritance are tightly coupled because changing the parent or superclass in an inheritance relationship risks breaking your code. […]