1. Preliminary knowledge
To write a code using Notepad, you need to install JDK (Java Developer Tools) and configure environment variables.
JVM is a software implemented with C/C++ code, called Java virtual machine.
We installed JDK, the reason why JVM appears because JDK contains JVM
2. Write a simple program
1. Write a program using Notepad
Create a new text document and change the suffix to .java
Write a HelloWorld program
2. Compile the .java file
Click win+R, enter cmd, transfer to the file we wrote, and then use j avac+filename.java to compile
3. Run the .class file
Use j avac+ file name to run in JVM
3. Possible problems
Not an internal command: JDK environment variables are not configured properly
No .class file is generated: no saving after writing