What are the rules for defining class names in Java?

In Java, class names must adhere to the following rules:

1. Class names must start with a letter, underscore, or dollar sign.
2. Class names can consist of letters, numbers, underscores, or dollar signs.
3. Class names cannot contain spaces.
4. The class name cannot be a keyword in Java.
5. Class names are case-sensitive, meaning that Hello and hello are two different class names.
6. Class names should be in camel case, with the first letter lowercase and the first letter of each subsequent word capitalized, for example: myClassName.
7. Class names should be descriptive and clearly express the functionality or purpose of the class.