Java Syntax Essentials: Comments, Operators, Data Types

Posted on Apr 6, 2025 in Social Anthropology

Java Fundamentals: Syntax and Operators

Java Comments Explained

In Java, there are three types of comments:

• // Single-line comments
• /* Comments of one or more lines */
• /** Documentation comment, one or more lines */

Java Identifiers: Naming Rules

Identifiers are used for naming variables, functions, classes, objects, or anything else the programmer needs to identify or use.

In Java, an identifier must begin with a letter, an underscore (_), or a dollar sign ($). Subsequent characters can be letters or digits. Java distinguishes between uppercase and lowercase letters (case-sensitive), and there is no maximum length for an identifier.

Valid identifiers include:

• ID
• username
• User_Name
• _variable_del_sistema
• $Transaction

Example usage:

int contador_principal;
char _lista_de_ficheros;
float $cantidad_en_Ptas;

Java Arithmetic Operators

Basic Arithmetic

Increment and Decrement Operators

Java Conditional Operators

Comparison Operators

Logical Operators

Java Bitwise Operators

Bitwise Shift Operators

Bitwise Logical Operators

Java Assignment Operators

Shortcut assignment operators:

Java Primitive Data Types

Java Control Flow Statements

Selection Statements

If Statement

if (condition) {
  // statement(s) if condition is true
}

If-Else Statement

if (condition) {
  // statement(s) if condition is true
} else {
  // statement(s) if condition is false
}

Switch Statement

switch (variable) {
  case value1:
    // Instructions
    break;
  case value2:
    // Instructions
    break;
  // ... more cases
  default:
    // Instructions if no case matches
}

Loop Statements

For Loop

for (initialization; termination_condition; increment/decrement) {
  // statement(s) to repeat
}

Do-While Loop

initialization;
do {
  // statement(s) to repeat
  increment/decrement;
} while (condition);

While Loop

initialization;
while (condition) {
  // statement(s) to repeat
  increment/decrement;
}

Alternative while loop structure:

while (boolean_expression) {
  // instructions...
}