Learning about the Environment
The Java environment consists of understanding a number of technologies. In the following
sections, we go over the key terms and acronyms you need to know and then discuss what
software you need.
Major Components of Java
The Java Development Kit (JDK) contains the minimum software you need to do Java
development. Key commands include:
- javac: Converts .java source files into .class bytecode
- java: Executes the program
- jar: Packages files together
- javadoc: Generates documentation
The javac program generates instructions in a special format called bytecode that the java command can run. Then java launches the Java Virtual Machine (JVM) before running the code. The JVM knows how to run bytecode on the actual machine it is on. You can think of the JVM as a special magic box on your machine that knows how to run your .class file within your particular operating system and hardware.
You might have noticed that we said the JDK contains the minimum software you need.
Many developers use an integrated development environment (IDE) to make writing and
running code easier. While we do not recommend using one while studying for the exam, it
is still good to know that they exist. Common Java IDEs include Eclipse, IntelliJ IDEA, and
Visual Studio Code.
