Install java compiler

why need java compiler?
transfer the human-readable code into computer understand code.

how to install?

1. download the JDK
2. install the JDK
3. change the path environment variable.

• copy the java/bin path
• open the computer properities
• click the advanced system setting
• click the environment variables
• new "path" and paste the java/bin path

4. go to the command line window and input "javac" and will see the result.(if there is no java compiler, the message will show "there is no external and internal command"something like that)