I learned Java almost 6 years ago when I was in university, and since then I have used it sparingly at work. Today I am starting a series where I chronicle my journey re-learning Java, taking extensive notes and summarizing them to share with you all.

Here is my first note that will start the series:

Notes

• Java is platform independent, meaning that you can write a program once, and as long as your host machine has JVM, it will just run - barring rare edge cases.

• Every class (in Java everything is inside a class) is compiled into a separate Java bytecode file that has the same name as the class but ends with the .class extension instead of the .java extension.

• Every Java program is a set of class definitions. To run a Java program, it must have a main method, which represents the entry point where the program starts when it is executed.

• To compile a Java source-code file, you can use the javac command. And to run a Java class, you use the java command. More typically though, you will use some kind of IDE which has shortcuts and buttons to do this for you.

• There can only be one public top-level class per .java file, and public top-level classes must have the same name as the source file.