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📚AP Computer Science A Unit 4 Vocabulary

170 essential vocabulary terms and definitions for Unit 4 – Data Collections

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📚Unit 4 – Data Collections
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📚Unit 4 – Data Collections

TermDefinition
1D arrayAn array with a single row of elements, organized in a linear sequence and accessed using a single index.
arrayA data structure that stores a fixed-size collection of elements of the same type in contiguous memory locations, accessed by index.
ArrayIndexOutOfBoundsExceptionAn error that occurs when attempting to access an array element using an index value outside the valid range of 0 through length minus one.
default valuesThe initial values automatically assigned to instance variables by the default constructor based on their data type (0 for int, 0.0 for double, false for boolean, null for reference types).
indexA numeric position in a string, starting from 0 for the first character and going up to one less than the length of the string.
initializer listA syntax used to create and initialize an array with specific values at the time of creation.
length attributeA property of an array that indicates the number of elements it contains and cannot be changed after creation.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
primitive valuesBasic data types in Java such as int, double, and boolean that store actual values directly.

TermDefinition
add(E obj) methodAn ArrayList method that appends an object to the end of the list and returns true.
add(int index, E obj) methodAn ArrayList method that inserts an object at a specified position and shifts elements to the right.
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
generic typeA parameterized type that specifies the data type of elements a collection will contain, such as ArrayList<E>.
get(int index) methodAn ArrayList method that returns the element at a specified position in the list.
import statementA Java statement used to make classes from a package available for use in a program.
indexA numeric position in a string, starting from 0 for the first character and going up to one less than the length of the string.
java.util packageA Java library package that contains utility classes including ArrayList.
mutableCapable of being changed or modified after creation, such as an ArrayList that can grow or shrink in size.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
remove(int index) methodAn ArrayList method that removes the element at a specified position and shifts elements to the left.
set(int index, E obj) methodAn ArrayList method that replaces the element at a specified position and returns the former element.
size() methodAn ArrayList method that returns the number of elements currently in the list.
type parameterA placeholder for a specific data type in a generic class, represented by E in ArrayList<E>.

TermDefinition
array indexThe numeric position used to access a specific element in an array.
array traversalThe process of using repetition statements to systematically access elements in an array.
enhanced for loopA Java loop construct that iterates through all elements of a collection without using an index variable.
enhanced for loop variableThe variable in an enhanced for loop header that is assigned a copy of each array element during each iteration.
indexed for loopA loop that accesses array elements by using their index positions to control iteration.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.
while loopAn iterative statement that repeatedly executes a block of code as long as a specified Boolean expression evaluates to true.

TermDefinition
algorithmA step-by-step procedure or set of rules designed to solve a problem or accomplish a task.
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
averageThe mean value calculated by dividing the sum of all values by the number of values.
delete elementsThe operation of removing elements from a collection.
duplicate elementsMultiple occurrences of the same value within a collection.
insert elementsThe operation of adding new elements into a collection at a specified position.
maximum valueThe largest value in a set of data or collection of numbers.
minimum valueThe smallest value in a set of data or collection of numbers.
reverseTo arrange elements in an array in the opposite order from their original sequence.
rotate elementsTo move elements in an array circularly so that elements shifted off one end reappear at the other end.
shift elementsTo move all elements in an array left or right by one or more positions.
sumThe result of adding multiple values together.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.

TermDefinition
array traversalThe process of using repetition statements to systematically access elements in an array.
averageThe mean value calculated by dividing the sum of all values by the number of values.
consecutive pairsTwo adjacent elements in an array that are next to each other in sequence.
duplicate elementsMultiple occurrences of the same value within a collection.
maximum valueThe largest value in a set of data or collection of numbers.
minimum valueThe smallest value in a set of data or collection of numbers.
reverseTo arrange elements in an array in the opposite order from their original sequence.
rotate elementsTo move elements in an array circularly so that elements shifted off one end reappear at the other end.
shift elementsTo move all elements in an array left or right by one or more positions.
sumThe result of adding multiple values together.

TermDefinition
2D arrayA two-dimensional data structure consisting of rows and columns used to store and organize data in a grid format.
algorithmA step-by-step procedure or set of rules designed to solve a problem or accomplish a task.
averageThe mean value calculated by dividing the sum of all values by the number of values.
consecutive pairsTwo adjacent elements in an array that are next to each other in sequence.
duplicate elementsMultiple occurrences of the same value within a collection.
maximum valueThe largest value in a set of data or collection of numbers.
minimum valueThe smallest value in a set of data or collection of numbers.
reverseTo arrange elements in an array in the opposite order from their original sequence.
rotate elementsTo move elements in an array circularly so that elements shifted off one end reappear at the other end.
shift elementsTo move all elements in an array left or right by one or more positions.
sumThe result of adding multiple values together.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.

TermDefinition
2D arrayA two-dimensional data structure consisting of rows and columns used to store and organize data in a grid format.
ArrayIndexOutOfBoundsExceptionAn error that occurs when attempting to access an array element using an index value outside the valid range of 0 through length minus one.
arrays of arraysA data structure where a 2D array is implemented as an array where each element is itself a 1D array.
column indexThe second index in the square brackets [row][col] notation used to specify which column of a 2D array to access.
default valuesThe initial values automatically assigned to instance variables by the default constructor based on their data type (0 for int, 0.0 for double, false for boolean, null for reference types).
initializer listA syntax used to create and initialize an array with specific values at the time of creation.
length attributeA property of an array that indicates the number of elements it contains and cannot be changed after creation.
object reference dataData types that store references to objects rather than primitive values.
primitive dataBasic data types in Java such as int, double, and boolean that store values directly.
row indexThe first index in the square brackets [row][col] notation used to specify which row of a 2D array to access.

TermDefinition
1D arrayAn array with a single row of elements, organized in a linear sequence and accessed using a single index.
2D arrayA two-dimensional data structure consisting of rows and columns used to store and organize data in a grid format.
arrays of arraysA data structure where a 2D array is implemented as an array where each element is itself a 1D array.
column-major orderA traversal pattern of a 2D array where elements are accessed down each column from top to bottom before moving to the next column.
enhanced for loopA Java loop construct that iterates through all elements of a collection without using an index variable.
nested iteration statementsLoop structures where one loop is placed inside another, used to access all elements in a 2D array.
row-major orderA traversal pattern of a 2D array where elements are accessed across each row from left to right before moving to the next row.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.

TermDefinition
algorithmic biasSystemic and repeated errors in a program that create unfair outcomes for a specific group of users.
biasSystematic prejudice or error in data collection or program logic that leads to unfair or inaccurate outcomes.
data collectionThe process of gathering information about individuals through computer systems and other means.
data qualityThe accuracy, completeness, and reliability of data in a dataset, which affects the correctness of programs and conclusions drawn from the data.
data setA collection of related data values that can be analyzed to answer questions or solve problems.
data set collection methodThe process and technique used to gather data for a dataset, which can introduce bias or affect data quality.
data storageThe process of keeping collected personal information on computer systems for later access or use.
inaccurate dataData that contains errors or does not correctly represent the actual values or facts, potentially causing program malfunction.
incomplete dataA dataset that is missing information or records, which can cause programs to work incorrectly or inefficiently.
personal dataInformation about individuals that can be used to identify them or reveal details about their lives, activities, or characteristics.
privacyThe right of individuals to control access to their personal information and have it protected from unauthorized collection, use, or disclosure.
safeguardProtective measures taken to prevent unauthorized access to or misuse of personal data.

TermDefinition
algorithmA step-by-step procedure or set of rules designed to solve a problem or accomplish a task.
chartA visual representation of data used to organize and display information in a way that aids understanding and planning.
data setA collection of related data values that can be analyzed to answer questions or solve problems.
tableA structured visual representation of data organized in rows and columns that can be used to plan algorithms.

TermDefinition
close()A Scanner method that closes the scanner and the associated file when the program is finished using it.
fileA storage location for data that persists when a program is not running and can be retrieved during program execution.
File classA Java class used to create a File object that connects a program to a text file for reading data.
hasNext()A Scanner method that returns true if there is another item to read in the file or input source, and false otherwise.
import statementA Java statement used to make classes from a package available for use in a program.
InputMismatchExceptionAn exception thrown when a Scanner method attempts to read a value that does not match the expected data type or is out of range.
IOExceptionAn exception class that is thrown when a file cannot be opened or read due to an invalid file name or I/O error.
java.io packageA Java package containing classes like File and IOException that must be imported to use file input/output operations.
next()A Scanner method that returns the next String token read from a file or input source.
nextBoolean()A Scanner method that returns the next boolean value read from a file or input source.
nextDouble()A Scanner method that returns the next double value read from a file or input source.
nextInt()A Scanner method that returns the next integer value read from a file or input source.
nextLine()A Scanner method that returns the next line of text as a String read from a file or input source.
Scanner classA Java class used to obtain and parse text input from the keyboard or other input sources.
split()A String method that returns a String array by dividing a String into substrings based on a given delimiter expression.
throws IOExceptionA method declaration clause that indicates the method may throw an IOException if a file cannot be opened.
while loopAn iterative statement that repeatedly executes a block of code as long as a specified Boolean expression evaluates to true.
whitespaceBlank characters such as spaces, tabs, and newlines that Scanner methods handle differently when reading from a file.

TermDefinition
arrayA data structure that stores a fixed-size collection of elements of the same type in contiguous memory locations, accessed by index.
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
ArrayList objectsResizable collections in Java that can dynamically grow or shrink and can be traversed recursively.
binary search algorithmA search algorithm that finds a target value in a sorted collection by repeatedly dividing the search space in half, eliminating half of the remaining elements with each iteration.
iterationA form of repetition in which code is executed zero or more times based on a condition.
iterativelyA method of solving a problem by repeating a set of instructions in a loop rather than through recursive function calls.
linear searchA search algorithm that examines each element in a collection sequentially from the beginning until the target value is found or the end is reached.
merge sortA recursive sorting algorithm that divides an array into smaller subarrays, sorts them, and then merges them back together in sorted order.
recursionA programming technique where a function calls itself to solve a problem by breaking it into smaller, similar subproblems.
recursive algorithmsAlgorithms that solve problems by having a function call itself with modified parameters until reaching a base case.
recursive callAn instance where a method invokes itself as part of its execution.
recursive sorting algorithmA sorting algorithm that uses recursion to divide and organize elements in a collection.
recursivelyA method of solving a problem by having a function call itself with modified parameters until a base case is reached.
sorted orderA requirement for binary search in which elements in a collection are arranged in a specific sequence, typically in ascending or descending order.
String objectsData structures in Java that represent sequences of characters and can be traversed recursively.
subarrayA contiguous portion of an array.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.

TermDefinition
base caseA condition in a recursive method that stops the recursion and prevents infinite calls.
iterative approachA method of solving a problem using loops and repetition instead of recursion.
local variablesVariables declared in the headers or bodies of blocks of code that can only be accessed within the block in which they are declared.
parametersVariables that allow procedures to be generalized and reused with a range of input values or arguments.
recursive callAn instance where a method invokes itself as part of its execution.
recursive methodA method that calls itself to solve a problem by breaking it down into smaller instances of the same problem.

TermDefinition
arrayA data structure that stores a fixed-size collection of elements of the same type in contiguous memory locations, accessed by index.
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
insertion sortAn iterative sorting algorithm that inserts elements from the unsorted portion into their correct position in the sorted portion by shifting elements to make room.
iterative sorting algorithmsSorting algorithms that use repetition to progressively sort elements by performing the same operation multiple times.
selection sortAn iterative sorting algorithm that repeatedly selects the smallest or largest element from the unsorted portion and places it in its correct final position in the sorted portion.
sorted portionThe part of a collection that has been arranged in the desired order during a sorting process.
sorting algorithmsStep-by-step procedures used to arrange elements in a collection in a specific order, such as ascending or descending.
swapThe operation of exchanging the positions of two elements in a collection.
unsorted portionThe part of a collection that has not yet been arranged in the desired order during a sorting process.

TermDefinition
2D arrayA two-dimensional data structure consisting of rows and columns used to store and organize data in a grid format.
arrayA data structure that stores a fixed-size collection of elements of the same type in contiguous memory locations, accessed by index.
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
linear search algorithmsStandard algorithms that check each element in a collection in order until the desired value is found or all elements have been checked.

TermDefinition
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
ConcurrentModificationExceptionAn exception that occurs when the size of an ArrayList is changed while traversing it using an enhanced for loop.
enhanced for loopA Java loop construct that iterates through all elements of a collection without using an index variable.
IndexOutOfBoundsExceptionAn exception that occurs when attempting to access an index value outside the valid range of an ArrayList.
iterationA form of repetition in which code is executed zero or more times based on a condition.
recursive statementsProgramming statements that call themselves to process elements in a data structure.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.

TermDefinition
autoboxingThe automatic conversion by the Java compiler from a primitive type to its corresponding wrapper class object, such as converting an int to an Integer or a double to a Double.
Double classA wrapper class in the java.lang package that represents a primitive double value as an object; Double objects are immutable.
immutableA property of String objects meaning that once created, their content cannot be changed; methods called on a String return a new String rather than modifying the original.
Integer classA wrapper class in the java.lang package that represents a primitive int value as an object; Integer objects are immutable.
parseDoubleA static method of the Double class that converts a String argument to a double value.
parseIntA static method of the Integer class that converts a String argument to an int value.
primitive typeA basic data type in Java such as int or double that is not an object.
unboxingThe automatic conversion by the Java compiler from a wrapper class object to its corresponding primitive type, such as converting an Integer to an int or a Double to a double.
wrapper classA class that encapsulates a primitive data type and provides object-oriented functionality, such as Integer and Double.