AP Computer Science A Ultimate Guide

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Names that are given to show data that are stored in the memory of a computer when a program is being executed in a computer

An error because of the incorrect way a code is structured.

A compiler doesn’t catch this error. It just causes an error with the execution of the program.

System.out.print(""); 

type identifier = value;

Basic types of data

It represents any number that is an integer. All positive, negative numbers and zero. Cannot store decimals.

A number that can be positive, negative, or zero, and it can be a fraction or decimal.

A value that is either true or false. True = 1, False = 0 in machine code.

It represents a single character that can be represented on a computer. It includes any character that you type on the keyboard. Stored with the use of single quotation marks or an apostrophe.

% - Returns the remainder once two numbers are divided.

A process in which data is forced to look like another type of data to the compiler.

int x;
double y = 4.5;
x = (int) y;

int x = 4;
double y;
y = (double) x;

(++) This increases the value of a number by one.

(--) This decreases the value of a number by one.

a = a + b

a = a - b

A data type created in Java.

An object data type which has a class with many methods that describe the behavior of an object.

Once an object is created, the assigned value cannot change.

data type created in Java

used to build objects

conditional statement that is used in Java to help control the flow of the program

==

&&

||

!=

to simplify common compound conditions, distribute the ! into the parenthesis and change the && to ||, or vice versa

loop cycles through again and again, while the condition is considered true

loop that repeats forever because of condition

statement 1 is executed (one time) before the execution of the code block.

statement 2 defines the condition for executing the code block.

statement 3 is executed (every time) after the code block has been executed.

when a group of statements, such as control structures, are all put together to be referred to this

group of code that performs specific task

This class houses the “guts” of the methods that the driver class calls.

defines method function

sets object’s initial values for instance variables

attributes in a class, also known as fields

a comment that is intended to inform the user more about the condition of the method and guarantees it to be true.

a condition that must always be true just after the execution of a section of code, or after an operation in a formal specification.

Made up of other data, and instances of other classes.

attribute that is shared among all instances of a class

a data structure that makes it easier to handle similar types of data

These search through the data one by one in order, and take a long time to execute

These search through the data for the desirable value by dividing it into half each time until the desired value is found

They take data in an array, and rearrange it into a particular order. They are very powerful because they can accomplish tasks faster, and can make your programs even more efficient.

This sort searches and swaps. Once it finds the lowest value, it will swap its position in the array with the data at index 0. The first element is now sorted. The process repeated for index 1. The rest of the array will be searched for the lowest value and is swapped with the data that is found at index 1.

It compares the first 2 elements, and depending on the outcome of this it inserts the second value in front of the first value into index 0, which moves the first value to index 1. The first 2 elements are sorted. Then the third element is checked and this process continues until it’s entirely sorted.

This type of sort uses recursion. An array is split into 2 pieces. The piece is sorted. The 2 sorted pieces are merged together into one sorted list. Then in order to sort each of the 2 pieces, the same method is used again until it is fully sorted.

A huge limitation of arrays is that it has a fixed length, and can only store, one specific type of data.

used to describe an array list which becomes bigger / smaller as elements are added / removed

array within an array, like a vending machine

A way to create a relationship amongst classes.

A way to determine how information travels amongst the classes. Ex: The subclasses inherit characteristics of the parent class.

when a class has more than 1 superclass, it is defined as ______. not allowed in java

new version of code takes over old version

When many classes are related to each other by inheritance. Inheritance lets us inherit attributes and methods from another class. uses those methods to perform different tasks.

characteristic to call a method itself

Signal the execution to stop the recursion and return to each prior recursive call