Java Variable Declarations and Naming

Study Notes

Naming Conventions

Variable, method, and object names should start with a lowercase letter.
Use uppercase letters to indicate word boundaries.
Only use digits and lowercase letters after the first letter.
Class names should start with an uppercase letter.

Identifiers

Java uses identifiers with predefined meanings.
Keywords: public, class, void, static
Predefined identifiers: System, String, println
A full list of reserved words and predefined identifiers is available in the textbook Appendix 1.

Variable Declarations

Every variable in a Java program must be declared before use.
A declaration specifies the variable's data type (the kind of data it will store).
The data type is followed by one or more variable names separated by commas and terminated with a semicolon.
Variables are typically declared before use or at the start of a block (indicated by an opening brace, '{').
Basic types in Java are called primitive types.

Primitive Types

Primitive types are the most basic data types built into Java.
They are not objects and hold their values directly in memory.
They are predefined by the language and named by a reserved keyword.

Primitive & Basic Types

int: Integers (whole numbers)
char: Single characters (stores any Unicode character)
double: Floating-point numbers (numbers with decimal points)
boolean: True or False values
String: Sequences of characters (not a primitive type, but often considered a basic type)

Examples

boolean tadiwaIsTheBestLecturer = True;
char singleCharacter = ‘%’;
double deCimal7 = 3.64;
double de_cimul = 2;
String sampleString = “This is a test”;

Description

This quiz covers the fundamental concepts of Java variable declarations, naming conventions, and identifiers. Test your understanding of how to declare variables, use keywords, and apply proper naming in Java programming. Ideal for beginners looking to solidify their Java knowledge.