1. The package name
Multiple words are lowercase xxxyyyzzz
2. The name of the class and interface names
Multi-word, the first letter of all words capitalized XxxYyyZzz
3. variables and method names
Multi-word, the first letter of the first word lowercase, followed by the first letter of the word capitalized army xxxYyyZzz
4. constant name
All capital letters, underlined each word in connection with multi-word, XXX_YYY_ZZZ