Java Basics Vocabulary

Vocabulary flashcards covering core concepts, syntax, control structures, and memory mechanics from the Java Basics supplement notes.

Java Application

A stand-alone Java program that runs directly on your computer.

Java Applet

A program that cannot run without the support of a browser or viewer, typically sent across the Internet to run remotely.

Object

A program construct that contains data and can perform certain actions.

Class

A category, kind, or type of object. Defines the data types and methods shared by all objects of that class.

Method

A block of code in a program that defines an action an object can perform.

Valued Method

A method that uses a return statement to return a result to the caller.

Void Method

A method that performs an action but does not return a result.

Identifier

A name used in Java to identify parts of a program (variables, classes, methods). Consists of letters, digits, underscores, and dollar signs; cannot start with a digit or contain spaces/special characters.

Unicode

A comprehensive character set used by Java that includes characters and symbols from non-English languages, unlike standard ASCII.

I/O (Input/Output)

The mechanism of receiving data (e.g., keyboard input) and displaying or storing results (e.g., screen output).

System.out

An object in the standard System class used to send text output to the display screen.

println

A method of the System.out object used to print text or data to the screen followed by a new line.

if-else Statement

A conditional branch statement that executes one block of code if a boolean expression evaluates to true, and another if it evaluates to false.

switch Statement

A multiway branch statement that evaluates a controlling expression to choose from several execution paths defined by case statements.

Controlling Expression

The expression in a switch statement whose evaluated value determines which case branch executes (must evaluate to int, char, byte, short, or String).

Enumeration (enum)

A special type used to define a fixed list of named constants, restricting a variable's value exclusively to those specified items.

Scope

The portion of a program in which a declared variable or constant exists and can be accessed, bounded by its enclosing braces {}.

Loop

A control structure that repeats a statement or group of statements until a termination condition is met.

Loop Body

The statement or block of statements that is repeatedly executed within a loop.

Iteration

A single execution of the statements contained inside a loop body.

while Loop

A loop control structure that evaluates a boolean expression prior to each iteration and continues repeating as long as that expression remains true.

String Class

A built-in Java class within the java.lang package used to represent and manipulate sequences of text characters.

ASCII

A character set that assigns a standard numeric code to each character used on a standard English-language keyboard.

Token

A contiguous group of characters treated as a single unit of data (such as an integer, word, or double) when parsed by a Scanner.

Delimiter

A character or set of characters used to separate individual tokens in input data (by default, Scanner uses whitespace).

Scanner Class

A utility class in Java used to parse primitive types and strings using regular expressions, capable of processing input from keyboard (System.in) or directly from a String.

Array

A special object in Java that stores a finite collection of items having the same data type in contiguous memory locations.

Index (Subscript)

An integer expression enclosed in square brackets [] that specifies the position of a specific element within an array, starting at 0.

Zero-Based Indexing

The convention where the first element of an array is located at index 0 and the last element is at index $N - 1$ (where N is the array length).

new Operator

The Java keyword used to instantiate objects and allocate memory locations.

Wrapper Class

A class in Java (e.g., Integer, Double, Character) that encapsulates a primitive type inside an object, allowing primitives to be treated as class types.

Autoboxing

The automatic conversion that the Java compiler makes between primitive types and their corresponding object wrapper classes (e.g., assigning an int directly to an Integer variable).

Primitive Types

The 8 basic Java data types (byte, short, int, long, float, double, char, boolean) that store raw values directly in memory rather than referencing objects.

Reference Types

Data types (classes, arrays, interfaces) whose variables store memory addresses (references) pointing to objects located on the heap, rather than raw values.

final Keyword

A modifier used to define constants (unmodifiable variables), prevent method overriding, or prevent class inheritance.

Type Casting

The explicit conversion of a value from one data type to another, written as (targetType) value.

Math Class

A utility class in java.lang containing static methods for common mathematical operations like Math.abs(), Math.pow(), Math.sqrt(), Math.max(), and Math.random().

for Loop

A loop control structure that combines initialization, boolean condition evaluation, and update expression in a single line.

for-each Loop

An enhanced loop structure designed to iterate sequentially over every element in an array or collection without using explicit indices.

do-while Loop

A post-test loop control structure that executes its body once before evaluating its controlling expression, ensuring at least one execution.

.length Field

A read-only public property of Java arrays that returns the total capacity/number of elements the array can store (note: field, not a method).

equals() vs ==

The == operator compares primitive values or reference memory locations; the .equals() method compares the actual state or contents of objects (e.g., String text).

Unboxing

The automatic conversion of a wrapper class object (e.g., Integer) back to its corresponding primitive value (e.g., int).