There are different types of programming languages. In some of them you write the text of the program (aka the source code) and can execute this program right away. These are interpreted languages (for example, JavaScript).
But Java requires the source code of your program to be compiled first. It gets converted to a bytecode that is run by Java Virtual Machine, which may turn some of it into a platform-specific machine code using the so-called Just-In-Time (JIT) compiler.
Not only will the program be checked for syntax errors by a Java compiler, but other libraries of Java code can be added (linked) to your program after the compilation is complete (deployment stage). There are plenty of readily available libraries of reusable components, and a vast majority of them are free of charge.
In this lesson you start with writing a very basic Java program that outputs the words “Hello World” on your computer’s monitor.
Technically you can write the source code of your Java program in any plain text editor that you prefer (Notepad, TextEdit, Sublime Text, vi, and so on), but to compile your program you need additional tools and code libraries that are included in the Java Development Kit (JDK).
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