JavaWorld Core Java

• Java Challengers #4: Comparing Java objects with equals() and hashcode() August 15, 2019
  In this Java Challenger you’ll learn how equals() and hashcode() combine to make object comparisons efficient and easy in your Java programs. Simply put, these methods work together to verify if two objects have the same values.  Without equals() and hashcode() we would have to create very large "if" comparisons, comparing every field from an […]
• Java Challengers #7: Debugging Java inheritance July 23, 2019
  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. […]
• Java 101: Interfaces in Java July 16, 2019
  Java interfaces are different from classes, and it's important to know how to use their special properties in your Java programs. This tutorial introduces the difference between classes and interfaces, then guides you through examples demonstrating how to declare, implement, and extend Java interfaces.You'll also learn how the interface has evolved in Java 8, with […]
• Java 101: Class and object initialization in Java July 9, 2019
  Classes and objects in Java must be initialized before they are used. You've previously learned that class fields are initialized to default values when classes are loaded and that objects are initialized via constructors, but there is more to initialization. This article introduces all of Java's features for initializing classes and objects. Note that code […]
• Java 101: Java polymorphism and its types May 30, 2019
  Polymorphism refers to the ability of some entities to occur in different forms. It is popularly represented by the butterfly, which morphs from larva to pupa to imago. Polymorphism also exists in programming languages, as a modeling technique that allows you to create a single interface to various operands, arguments, and objects. Java polymorphism results […]
• Java tip: Fields and methods in Java May 16, 2019
  The Java tutorial Java 101: Classes and objects in Java introduces the fundamentals of Java classes and objects, including how to declare classes, describe attributes via fields, describe behaviors via methods, initialize objects via constructors, and instantiate objects from classes and access their members. To read this article in full, please click here(Insider Story)
• Java 101: Inheritance in Java, Part 2: Object and its methods May 7, 2019
  Java provides a standard class library consisting of thousands of classes and other reference types. Despite the disparity in their capabilities, these types form one massive inheritance hierarchy by directly or indirectly extending the Object class. This is also true for any classes and other reference types that you create.The first half of this tutorial on […]
• Java 101: Inheritance in Java, Part 1: The extends keyword May 7, 2019
  Java supports class reuse through inheritance and composition. This two-part tutorial teaches you how to use inheritance in your Java programs. In Part 1 you'll learn how to use the extends keyword to derive a child class from a parent class, invoke parent class constructors and methods, and override methods. In Part 2 you'll tour java.lang.Object, […]
• Java 101: Classes and objects in Java May 7, 2019
  Classes, fields, methods, constructors, and objects are the building blocks of object-based Java applications. This tutorial teaches you how to declare classes, describe attributes via fields, describe behaviors via methods, initialize objects via constructors, and instantiate objects from classes and access their members. Along the way, you'll also learn about setters and getters, method overloading, […]
• Java 101: Loop, switch, or take a break? Deciding and iterating with Java statements May 1, 2019
  Java applications evaluate expressions in the context of statements, which are used for tasks such as declaring a variable, making a decision, or iterating over statements. A statement can be expressed as a simple or a compound statement: A simple statement is a single standalone instruction for performing a task; it must be terminated with […]