Reference

• https://www.w3schools.com/java/default.asp

• https://docs.oracle.com/javase/tutorial/

• https://docs.oracle.com/en/java/javase/17/docs/api/index.html

• https://github.com/openjdk/jdk.git

  Clone it and you can find the source code in src/java.base/share/classes/java/lang/System.java for java.lang.System.