AP CSA : CodeHS Definitions

AP Comp-sci terms/concepts to know, core principals and basics to help understand it better, also commands to know and examples

Debugging

Fixing a problem in your code

Syntax error

An error in the sequence of words or rules in a program that prevents the program from running

Algorithm

System.out.println();

Java method that lets us print out a line of the output to the use

System.out.print

Java method that lets us print output to the user, without ending the line printed.

String

A java type that represents a string of characters (text)

Syntax

Rules for writing code in a specific programming language

Variable

A symbol or container that holds a value

Primitive Type

Basic, simple data types that are inherent to Java (int, double, char, boolean)

Boolean

A true or false value

Reference Type

Reference variables store the address of the value

Data Type

A way to classify the information you can use in programming (numbers, words, true/false values)

Reassignment

Process of changing the value stored in a variable

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. (ex. 3 / 2 = 1 instead of 1.5, the decimal is decimated (literally lol))

Escape Sequence

Characters with special meanings

Arithmetic Expression

Combination of numbers, operators and sometimes variables that computes a value

Truncation

To trim some digits of a float or double-type number or some characters of a string from the right

Variable

A symbol or container that holds a value

Scanner class

A class within java.util, contains code specifically designed to help with user input

Assignment Statement

A line of code that assigns a value to a variable using the = operator

Input Buffer

A temporary memory area where input from the user is stored before being processed

Casting

Turning something of one type, into another type

Order of Operations

The order in which mathematical expressions should be evaluated, starts with parentheses, exponents, multiplications and division, addition and subtraction

Round-Off Error

The difference between the calculated approximation of a number and its exact mathematical value due to rounding

Integer Overflow

An error that occurs when the result of an integer operation does not fit within the allocated memory space

Truncate

To remove the digits of the right of the decimal point without rounding

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;

Comment Out

Commenting out code makes the computer ignore it, so it does not run.

Precondition

Assumptions we make about what must be true before a method is called

Postcondition

What should be true after a method is called

Single Line Comment

// this is a single line comment

Multi-Line Comment

/* This is a multi-Line comment*/

Javadoc Comment

/** 1. One sentence description of code’s function. 2. Preconditions 3. Postconditions 4. Block tags */

Argument

A variable passed as a value to a function

Method

A method is a way to teach the computer a new command

Parameter

A variable that receives a value passed into a method from outside the method

Method signature

A method’s signature is the name of the method and the parameter list

Method overloading

Classes can have multiple methods with the same name, as long as the parameters to those methods are different

Return type

Indicates what type value is being returned from the method

Void

A return type that means the method does not return a value

Instance method

A method that defines the behavior of an object, defines an action the object can perform

Static methods

Methods that can be called w/o creating an object of class, called using dot operator along with class name, unless defined in the enclosing class

Encapsulation

Process of hiding the implementation details of a class from the user

Modularization

Organizing code into smaller, reusable pieces

Math Class

A part of the java.lang package, contains only static methods

Math.random

Can be manipulated to produce a random int or double in a defined range
Ex: Math.random()