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• Identifiers can include a-z (or) A-Z (or) 0 to 9 (or) _ (or) $
• Identifiers must start with an alphabet (or) _ (or) $ for example, age, $salary, _value, __1_value.
• Identifiers cannot have other symbols, keywords, start with number for example, 123abc, -salary.
• Most importantly, identifiers are case sensitive.

Let's see some example,

package com.praveen.identifiers;

public class IdentifierDemo {

	public static void main(String[] args) {

		int abc = 992;
		int 1bc = 22; // compiler error as identifier cannot start with number
		byte Abc = 10;
		float $xyz = 10.2f;
		double _xyz = 10.21d;
		int #xyz = 989; // compiler error as identifier must start with an alphabet (or) _ (or) $
		int this = 212; // compiler error as identifier cannot have keywords

	}

}

As a Developer, we need to follow the below coding conventions:

1. Class Names:

   • Use PascalCase (capitalize the first letter of each word) for class names.
   • Example: UserAccount, OrderDetails.

2. Variable Names:

   • Stick to camelCase (start with a lowercase letter and capitalize subsequent words) for variables.
   • Example: userId, orderAmount,isActive.

3. Constants:

   • Use ALL_CAPS with underscores to separate words for constants.
   • Example: MAX_RETRIES, API_TIMEOUT, DEFAULT_VALUE.