AP CSA Unit 1: Primitive Types

String

String is a Java type that represents a string of characters (text).

String Literals

A sequence of characters enclosed in double quotations “ “.

Java Main Skeletons

Includes the class and main method arguments. Must include both in order to run successfully.

public static void main(String args[])

Main method. Code to be run must be placed within the main method.

public class MyProgram

Class. The name of MyProgram must match the name of the file.

System.out.print

Displays output on the computer monitor.

System.out.println

Displays output on the computer monitor and moves cursor to next line.

Variable

A symbol or container that holds a value.

int

int is a Java type that represents an integer (a whole number).

char

char is a Java type that represents a single character (a single letter).

double

double is a Java type that represents a real number with decimal values

Declare a variable

Declaring a variable is defining it for the first time.

Initialize a variable

Initializing a variable is giving it an initial value, or a starting value.

Primitive Type

Primitive types are the basic, simple data types that are inherent to Java (int, double, char, and boolean).

Boolean

A boolean is a true or false value.

Reference Type

Reference variables store the address of the value.

final

Prevents variables from changing value.

Modulus operator

The modulus operator (written as % in most programming languages) divides two numbers and returns the remainder.

Integer Division

When two integers are divided, the decimal values are truncated, or chopped off.

Order of Operations

The order in which mathematical expressions should be evaluated. Starts with Parentheses, Exponents, Multiplications and Division, Addition and Subtraction.

Literal

The fixed value being assigned to a variable. Often primitive data types.

ArithmeticException

Exception that is thrown to warn programmers about arithmetic errors in their code.

Increment

Increase the value of a variable by one. variable++;

Decrement

Decrease the value of a variable by one. variable–;

Compound Assignment Operators

Allows programmers to shortcut variable assignments that include the variable being assigned a new value: x = x + y; shortcut: x += y;