Java Technologies: Beginner to Advanced

Meet the Java Virtual Machine The Java Virtual Machine, or JVM, is the engine that runs every Java program. When you compile a .java file, the javac compiler does not create ...

Declaring Variables A variable is a named container in memory that holds a value of a fixed type. In Java you write the type first, then the name, then an optional initial value. ...

Decision Making with if and else Control flow decides which parts of your program run, how many times they run, and in what order. The simplest decision tool is the if statement. ...

Classes Are Blueprints A class is a blueprint that describes what an object looks like and what it can do. The blueprint lists fields, which store state, and methods, which define ...

Inheritance in Java Inheritance lets one class build on another. The keyword extends creates a subclass that inherits the fields and methods of its parent. A subclass can override ...

What Is an Exception? An exception is an event that interrupts the normal flow of a program. Java models failures as objects. When code runs into a problem, it throws an ...

Why Collections? Arrays are fine when the size is fixed, but most programs need structures that grow and shrink. The Java Collections Framework supplies reusable containers built ...

The Lambda Syntax A lambda is a compact way to write a function as an expression. Instead of an anonymous class with boilerplate, you write parameters, an arrow, and a body. ...

Processes and Threads A process is a running application with its own memory. A thread is a single path of execution inside that process. Modern CPUs run several cores, and Java ...

Why Maven Real Java applications have dependencies, resources, and tests. Maven is a build tool that brings order to all of it. It reads one central file, pom.xml , to learn what ...