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💻AP Computer Science A Unit 1 Vocabulary

165 essential vocabulary terms and definitions for Unit 1 – Using Objects and Methods

Study Unit 1
Practice Vocabulary
💻Unit 1 – Using Objects and Methods
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💻Unit 1 – Using Objects and Methods

TermDefinition
booleanA primitive data type that holds one of two values: true or false.
Boolean valueData values that can only be true or false, used in logical operations and conditional statements.
data typeA classification that specifies what kind of value a variable can store and what operations can be performed on it.
doubleA primitive data type used to store real numbers (numbers with decimal points).
intA primitive data type used to store integer values (whole numbers).
primitive data typeBasic data types in Java such as int, double, boolean, and char that are not objects.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.
variableA named storage location in a program that holds a value of a specific data type; the value can change while the program is running.

TermDefinition
arithmetic expressionMathematical expressions consisting of numeric values, variables, and operators that perform calculations.
castingThe process of converting a value from one primitive data type to another, such as from double to int or int to double.
casting operatorOperators used to convert a value from one data type to another, such as converting a double to an int.
data typeA classification that specifies what kind of value a variable can store and what operations can be performed on it.
doubleA primitive data type used to store real numbers (numbers with decimal points).
intA primitive data type used to store integer values (whole numbers).
integer expressionA mathematical or computational expression that evaluates to an integer value.
integer overflowAn error that occurs when an integer expression evaluates to a value outside the allowed range for the int data type, resulting in an unexpected value.
Integer.MAX_VALUEA Java constant that holds the largest possible value that can be stored in an int variable.
Integer.MIN_VALUEA Java constant that holds the smallest possible value that can be stored in an int variable.
out of rangeA value that exceeds the maximum or minimum limits allowed for a particular data type.
precisionThe degree of exactness with which a floating-point number can be represented in computer memory.
primitive data typeBasic data types in Java such as int, double, boolean, and char that are not objects.
round-off errorAn error that occurs when a computed value cannot be exactly represented in the available memory and must be rounded to the nearest representable value.
roundingThe process of converting a decimal number to the nearest integer value.
truncationThe removal of digits to the right of the decimal point when casting a double value to an int value.
wideningThe automatic conversion of a value from a smaller primitive type (like int) to a larger primitive type (like double).

TermDefinition
call by valueA method of passing arguments where the parameters are initialized with copies of the argument values rather than references to the original values.
constructorA special method that is called to create and initialize an object of a class, having the same name as the class.
constructor argumentA value passed to a constructor when it is called that must match the type, order, and number of parameters in the constructor signature.
constructor signatureThe combination of a constructor's name (same as the class name) and its ordered list of parameter types that uniquely identifies the constructor.
flow of controlThe order in which statements in a program are executed, which can be interrupted by method calls and resumed after the method completes.
newA Java keyword used to create a new instance of a class by allocating memory and calling the constructor.
nullA special value indicating that a reference variable does not currently reference any object.
objectA specific instance of a class with defined attributes and behaviors.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
overloaded constructorMultiple constructors in the same class that have different signatures, allowing objects to be created with different sets of parameters.
parameterA variable declared in the header of a method or constructor that receives values passed to the method when it is called.
parameter typesThe data types of the values that are passed to a constructor or method.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.
variableA named storage location in a program that holds a value of a specific data type; the value can change while the program is running.

TermDefinition
attributeThe data or properties that define the state of an object or class.
behaviorThe methods or actions that an object or class can perform.
classA formal implementation or blueprint that defines the attributes and behaviors of objects.
inheritanceA relationship in which a subclass draws upon and reuses the attributes and behaviors of a superclass.
instanceA specific occurrence or realization of a class with its own set of attribute values.
memory addressThe location in computer memory where an object is stored, which is referenced by a reference type variable.
objectA specific instance of a class with defined attributes and behaviors.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.
subclassA class that extends a superclass and inherits its attributes and behaviors.
superclassA class that contains common attributes and behaviors shared by multiple related classes.

TermDefinition
APIAn application programming interface that provides a specification informing programmers how to use classes and libraries.
attributeThe data or properties that define the state of an object or class.
behaviorThe methods or actions that an object or class can perform.
classA formal implementation or blueprint that defines the attributes and behaviors of objects.
libraryCollections of classes that can be utilized to create objects and are documented in API specifications.
methodA named block of code that only runs when it is called, allowing programmers to reuse code and organize programs into logical sections.
objectA specific instance of a class with defined attributes and behaviors.
packageOrganizational groupings of classes within APIs and libraries.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.

TermDefinition
argumentA value or variable passed to a method or constructor when it is called.
call by valueA method of passing arguments where the parameters are initialized with copies of the argument values rather than references to the original values.
constructorA special method that is called to create and initialize an object of a class, having the same name as the class.
flow of controlThe order in which statements in a program are executed, which can be interrupted by method calls and resumed after the method completes.
methodA named block of code that only runs when it is called, allowing programmers to reuse code and organize programs into logical sections.
method callAn invocation of a method that interrupts sequential execution and causes the program to execute the method's statements before returning control to the calling location.
method signatureThe combination of a method's name and its ordered list of parameter types, used to identify and call a specific method.
non-void methodA method that returns a value of a specified type that can be stored in a variable or used as part of an expression.
overloaded methodMultiple methods with the same name but different method signatures, allowing the same method name to be used with different parameter types or numbers.
parameterA variable declared in the header of a method or constructor that receives values passed to the method when it is called.
parameter listThe list of parameters in a method signature that specifies the types and order of arguments the method expects.
procedural abstractionThe ability to use a method by knowing what it does without needing to understand how it was implemented.
return statementA statement that terminates method execution and returns control flow to the point immediately following where the method was called.
return valueThe value produced by a non-void method that matches the return type specified in the method header.
void methodA method that does not return a value and cannot be used as part of an expression.

TermDefinition
additionThe arithmetic operator (+) that combines two numeric values to produce their sum.
arithmetic expressionMathematical expressions consisting of numeric values, variables, and operators that perform calculations.
ArithmeticExceptionAn exception that occurs when attempting to divide an integer by zero.
compound expressionExpressions that use multiple operators to combine numeric values.
divisionThe arithmetic operator (/) that divides one numeric value by another.
doubleA primitive data type used to store real numbers (numbers with decimal points).
escape sequenceA special sequence of characters starting with a backslash that has a special meaning in Java, such as \" for double quote, \\ for backslash, and \n for newline.
intA primitive data type used to store integer values (whole numbers).
integer divisionDivision of two int values that results in only the integer portion of the quotient, discarding any fractional part.
literalThe code representation of a fixed value.
multiplicationThe arithmetic operator (*) that produces the product of two numeric values.
numeric valueNumbers used in expressions, which can be of type int or double.
operatorSymbols that perform operations on numeric values in expressions.
operator precedenceThe rules that determine the order in which operators are evaluated in an expression, with multiplication, division, and remainder evaluated before addition and subtraction.
parenthesesSymbols used to modify operator precedence and control the order of operations in an expression.
remainder operatorThe operator (%) that computes the remainder when one number is divided by another.
string literalA sequence of characters enclosed in double quotes used to create a String object directly in code.
subtractionThe arithmetic operator (-) that finds the difference between two numeric values.
System.out.printA Java method that displays information on the computer display without moving the cursor to a new line after the output.
System.out.printlnA Java method that displays information on the computer display and moves the cursor to a new line after the output.
variableA named storage location in a program that holds a value of a specific data type; the value can change while the program is running.

TermDefinition
API documentationDocumentation generated from Javadoc comments that describes the functionality and usage of code.
block commentComments in Java denoted by /* */ that span multiple lines or create a block of explanatory text.
commentExplanatory text in code that describes functionality and is ignored by the compiler during program execution.
Javadoc commentComments in Java denoted by /** */ that are used to generate API documentation.
line commentComments in Java denoted by // that apply to a single line of code.
postconditionA condition that must always be true after a method executes, describing the outcome in terms of return values or object attributes.
preconditionA condition that must be true immediately before a method executes in order for the method to behave as expected.

TermDefinition
compareTo() methodA String method that compares two strings alphabetically and returns a negative value if the first string is less than the second, zero if they are equal, or a positive value if the first string is greater than the second.
concatenationThe process of combining two or more String objects or a String with a primitive value using the + or += operator to create a new String object.
equals methodA String method that returns true if the string contains the same sequence of characters as another string, and false otherwise.
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.
implicit conversionThe automatic conversion of a primitive value to a String object when concatenated with a String.
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.
indexOf() methodA String method that returns the index of the first occurrence of a specified substring, or -1 if the substring is not found.
java.lang packageA Java package containing fundamental classes that are automatically available without explicit import statements.
length() methodA String method that returns the number of characters in a String object as an integer.
method overridingWhen a public method in a subclass has the same method signature as a public method in the superclass but with subclass-specific behavior.
Object classThe superclass in Java from which all classes inherit, guaranteeing the existence of the toString method.
String class constructorA method that creates a new String object by calling the String class constructor.
string literalA sequence of characters enclosed in double quotes used to create a String object directly in code.
String objectAn instance of the String class in Java that represents a sequence of characters.
StringIndexOutOfBoundsExceptionAn exception thrown when attempting to access a string index that is outside the valid range of 0 to length - 1.
substring() methodA String method that returns a portion of a string, either from a starting index to an ending index, or from a starting index to the end of the string.
toString methodA method that returns a string representation of an object, automatically called when an object is concatenated with a String.

TermDefinition
algorithmA step-by-step procedure or set of rules designed to solve a problem or accomplish a task.
code compilationThe process of translating source code written by a programmer into machine-readable instructions that a computer can execute.
code executionThe process of running compiled code on a computer to perform the instructions specified in the program.
compilerA program that translates source code into machine code and checks for errors that must be fixed before the program can run.
compiler errorErrors in source code that are detected by a compiler and must be fixed before a program can be executed.
exceptionA type of run-time error that occurs as a result of an unexpected error not detected by the compiler and interrupts the normal flow of program execution.
integrated development environmentA software application that provides comprehensive tools for writing, compiling, and running code in one unified interface.
logic errorA mistake in the algorithm or program that causes it to behave incorrectly or unexpectedly, detected through testing with specific data.
patternRecurring sequences or structures found in everyday processes that can be represented and analyzed.
run-time errorA mistake in the program that occurs during execution and typically causes the program to terminate abnormally.
sequencingThe order in which steps in a process are completed, with steps executed one at a time.
syntax errorA mistake in a program where the rules of the programming language are not followed, detected by the compiler.
text editorA software tool used to write and edit source code in plain text format.

TermDefinition
dot operatorThe symbol (.) used in Java to access instance methods and properties of an object.
instance methodsMethods that belong to an object and are called on specific instances of a class using the dot operator.
null referenceA reference variable that points to no object, which will cause a NullPointerException if an instance method is called on it.
NullPointerExceptionAn exception that occurs when a method is called on a null reference instead of a valid object.

TermDefinition
class methodsMethods that are associated with a class rather than with instances of the class, and include the static keyword in their header.
dot operatorThe symbol (.) used in Java to access instance methods and properties of an object.
staticA keyword used in a method header to indicate that the method is a class method associated with the class itself, not with individual instances.

TermDefinition
abs()A Math class method that returns the absolute value of a numeric parameter.
built-in mathematical librariesPre-written code libraries in Java that contain mathematical functions and methods available for use without needing to write them from scratch.
casting operatorOperators used to convert a value from one data type to another, such as converting a double to an int.
class methodsMethods that are associated with a class rather than with instances of the class, and include the static keyword in their header.
exclusive endpointAn endpoint of a range where the boundary value is not included in the possible results.
inclusive endpointAn endpoint of a range where the boundary value is included in the possible results.
java.lang packageA Java package containing fundamental classes that are automatically available without explicit import statements.
Math classA Java class in the java.lang package that contains static methods for performing mathematical operations.
pow()A Math class method that returns the value of the first parameter raised to the power of the second parameter.
random()A Math class method that returns a random double value greater than or equal to 0.0 and less than 1.0.
sqrt()A Math class method that returns the nonnegative square root of a double value.

TermDefinition
assignment operatorThe = symbol that allows a program to store the value of an expression on the right into a variable on the left.
assignment statementA statement that stores a value in a variable using the assignment operator or a compound assignment operator.
data typeA classification that specifies what kind of value a variable can store and what operations can be performed on it.
expressionA combination of values, variables, and operators that is evaluated to produce a single value.
initializationThe first assignment of a value to a variable.
inputData or information provided to a program, which can come from various sources such as keyboard, files, or user interactions.
nullA special value indicating that a reference variable does not currently reference any object.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.
Scanner classA Java class used to obtain and parse text input from the keyboard or other input sources.
text inputData entered by a user in the form of characters and strings, typically from a keyboard.
variableA named storage location in a program that holds a value of a specific data type; the value can change while the program is running.

TermDefinition
assignment statementA statement that stores a value in a variable using the assignment operator or a compound assignment operator.
compound assignment operatorOperators (+=, -=, *=, /=, %) that perform an arithmetic operation and assign the result to a variable in a single statement.
post-decrement operatorThe -- operator used after a variable to subtract 1 from its stored value and assign the new value to the variable.
post-increment operatorThe ++ operator used after a variable to add 1 to its stored value and assign the new value to the variable.