Programming Variables and Documentation

Variables in Java

• Variables store data that can change based on conditions or inputs during program execution.
• Java syntax for declaring a variable: Data Type Variable Name = Value.
• Example: String User_Name = "Juan Dela Cruz".

Program Documentation

• Enhances program readability and understanding.
• Consists of comments, which are ignored by compilers/interpreters.

Types of Comments in Java

• Multiple line comments: Enclosed by /* comment */.
• Single line comments: Prefixed with //.

Identifiers in Java

• Names assigned to program elements like variables, functions, or arrays.
• Must start with a letter or an underscore; digits are allowed afterward.
• Case-sensitive: Uppercase and lowercase letters are distinct.
• Examples of valid identifiers: Salary_Per_Month, _area_cir, Age, PESONS_NAME.
• Invalid identifiers include those starting with a digit or reserved words.

Variable Rules

• Allowed: Letters, digits, underscore (_), and dollar signs ($), though usage of $ is discouraged.
• Not allowed: Special characters (other than _ and $), leading digits, spaces, or reserved words.
• A 'final' variable is one whose value cannot change after initialization.

Importance of Comments

• Aids in understanding and maintenance of code.
• Vital for documenting the purpose and workings of code sections.

Data Types

• Refers to the categorization of data allowing for a defined range of values and operations.
• Examples include integers, floats, strings, etc.

Reserved Words

• Predefined keywords in Java that cannot be used as variable names (e.g., while, class, public).

Operators in Java

• Arithmetic Operators: Perform basic math operations.
• Relational Operators: Determine relationships between variables (e.g., ==, !=).
• Logical Operators: Facilitate logical operations (e.g., &&, ||).
• Bitwise Operators: Perform operations at the bit level, shifting bits as needed.
• Assignment Operators: Used to assign values to variables (e.g., =).