Beginner Java

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Welcome to KnowledgeCity's Course on Programming with Java. My name is Cliff Brozo and I'll be your instructor for this class. So what is Java? Well, back in 1995, it was created by Sun Microsystems, and then a few years later, in 2009, it was bought out by Oracle. Today, more than three billion devices run Java. We're going to need to use an Integrated Development Environment called an IDE, and the best one out there is called IntelliJ, and you could see that a lot of people pay for it, and there is also a free version. We're gonna use the free version. When Java was first created, they came up with this mantra called write once, run anywhere, and basically that means that you can create Java code on one machine and run it on any other machine. So what happens is we as programmers create the Java source code. We write a little program and then that source code is sent to a compiler. The compiler turns it into byte code and the byte code then becomes a class file, and the code in the class file is similar to the assembler language way back in the olden days. So there are a lot of programming languages like C and C++ and they require compilers which turn the code into platform specific machine code. But languages like JavaScript and, oh, by the way, JavaScript is not Java. Java is much more powerful, but languages like JavaScript and Python are interpreted and that means that the computer executes the instructions one-by-one as it reads through them. What Java does is it combines both technologies. Java compiles a program into byte code and generates a class file and that class file is then interpreted by the Java virtual machine to run on any platform and any operating system. There are a bunch of keywords that we're going to need to memorize. We're going to need to understand how to declare and use a class in Java. We'll learn what a public access modifier is. We'll talk about static variables and how they save memory. We'll learn about the word void and you might think it means nothing, but it really does serve as a placeholder. The main key word is the starting point of our program. We'll learn about string arrays and we'll call them args because everybody else does and we can pass input to those string arrays in our Java program, and last, but not finally, we'll learn about the system outprint line where we'll be printing information to the screen. The next steps that we have to take will be to download the Java Development Kit and we'll get that from Oracle. We'll also download the Integrated Development Environment, better known as the IDE called IntelliJ, and we'll download the Java Runtime Environment called the JRE. We'll get that directly from Java. We'll also look at an online compiler where we'll be able to generate our code and not worry about the byte code in the class files. All that will be happening for us, but this is a wonderful testing environment, and we'll explore how to write Java code right here in this window. Grab yourself a cup of coffee and let's go. I'll see you soon.