It is worth pointing out that Java has some very handy naming conventions. It is advisable to both use meaningful names and to follow these naming conventions while developing software in Java for good maintenance and readability of code.
Class names should be nouns that are written in UpperCamelCase, namely with the first letter of each word capitalized including the first. For example, ArrayList, Scanner, StringBuilder, System, etc.
Method names use lowerCamelCase which start with a verb that describes the action they perform. This means that method names start with a lower case letter, and use upper case for each internal-word method names. For example, isInt(), nextLine(), getDenominator(), setNumerator(), etc.
Constants are in all upper case letters or in upper snake case, which also known as screaming snake case, and which is a naming convention in which each word is written in uppercase letters, separated by underscores. For example, Math.MAXINT or MAX_INT.
Incorrect. Leading underscores are valid in both Java and Python (commonly used in Python for private/protected attributes).
variable_name
Incorrect. Snake_case names with underscores are valid in both languages (and are actually standard convention in Python).
$variableName
Correct! Java allows the dollar sign ($) in variable names, but Python generates a SyntaxError because $ is not a permitted identifier character in Python.
variableName2
Incorrect. Numbers at the end of variable names are valid syntax in both Java and Python.
