1. Download JDK address https://www.oracle.com/technetwork/java/javase/downloads/index.html
2. Click to download
3. I installed JDK installation directory is C: \ tool \ Java \ jdk-12.0.2
4. Set Environment Variables
(1) find the System Settings => Advanced Settings
(2) Advanced => Environment Variables => User Environment Variables => New
(3) set three new user variables (not new, there are edit)
JAVA_HOME C:\tool\Java\jdk-12.0.2
CLASSPATH .;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\tools.jar;
Paht % JAVA_HOME% \ bin
5. Check whether the JDK installation is successful, the environment variable is set correctly
(1) win + R => CMD input
(2) Enter java -version, java, javac three correct order shall be shown in FIG.
