Java First Lesson: Installing environment variables and implementing Hello World with Notepad

1: Download Java tools

Jdk:java Development Kit (Java Development Essentials)
Jre:java Runtime Environment (Java execution Environment)

The JDK contains the JRE.

2: Install JDK
Set environment variables (can be user variable "self" or system variable "entire"), pointing to the bin directory in the JDK installation directory

By running, enter CMD to open the Command line window "Alt+r", enter java–version, display the Java version information

3: Write the program:

You can use Windows Notepad to write Java programs directly, or you can use advanced text editing tools such as Editplus,ultraedit to write Java programs, and you can use a professional IDE (Integrated development Environment) is written.

The class file is a bytecode file, and the program eventually executes the bytecode (bytecode) file.
Compile command: Java Test.java
Execute command: Java Test (note that there is no. class after Test)

①window---Show view---Navigator (open file); window---show view---console

②window---Show view---Package Explorer (open file)

Java First Lesson: Installing environment variables and implementing Hello World with Notepad