CS302 Glossary of Terms

This is a partial list of terms used in CS302. If you think an important term is missing, please let me know.

accessor: a method for extracting information from an object, usually named according to the variable being accessed, as in getData. Accessors usually declared public so that the actual variables of the instance can be declared protected or private without losing a handle to that data. see also mutator
actual parameters: the values that are passed into a procedure or method. These are always copies of either primitives or object references.
address: a location in memory; each data item is stored at a particular memory address
base case: the simplest case, usually the termination case for a recursive algorithm
binding: the relation between a symbol and its value
call stack (or execution stack): the part of memory containing the bindings of formal parameters to actual values for procedure calls
class: a definition of a type of object
constructor: a method used to create a new object
data: information that is manipulated by a computation
data flow model: a model of computation in which each computational component is represented as a box whose arguments and results may be connected from and to other boxes
expression tree: a diagram showing the operators and operands of an expression
final: keyword that may be applied to classes, methods, and data which will prevent it from being extended, overriden, or changed, respectively
formal parameter: the parameters declared for a method or procedure, into which the actual parameter values will be copied
garbage: memory that had been allocated but is no longer reachable by a process
garbage collection: claiming unreachable storage for reuse
heap: an area of memory from which space for dyanamic structures are allocated
infix notation: a notation in which operators appear between the operands, as in 3 + 5
instance variables: the variables holding the internal representation of an object
interface: (see abstraction barrier)
internal representation: the data representation (stored in the instance variables) of an object
iteration: a repeated computation, usually performed on a range of values or on the elements of a data structure
iterator: an object that contains a reference to internal items of a data structure in order to support iterating over the data in those items without exposing the internal representation of the structure itself
linked list: a data structure consisting of a sequence of values linked together in memory by a chain of references
liveness: the program will eventually provide a result
loop: a programming language construct that supports iteration (for example, a while loop)
loop invariant: a property of, or relationship among, the values of the loop variables such that the property is true both initially and after each iteration of the loop; together with the termination condition, a loop invariant is useful in demonstrating the correctness of a loop
memory: a place in the computer where values are stored for later retreival
message-passing: a way of thinking about object-oriented programming in which objects communicate by sending messages to each other (to invoke methods on them)
method: an operation that one may invoke on an object
mutation: the act of changing the values of variables or data structures
native: a method modifier that indicated that the method is defined elsewhere and in another platform-dependent fashion. Native methods should have a semicolon in place of its body.
object: an abstraction that encapsulates data and knows how to operate on the data
parameter: the way values are passed to a method or procedure
polymorphism: treating objects of many types in a uniform way
predicate: an expression that evaluates to either true or false
prefix notation: a notation in which operators appear before the operands, as in add(3,5)
primitive data: data, such as numbers and symbols, that are built into the language
procedure: a description of an activity to be carried out (by a computer)
process: an activity (carried out by a computer)
programming language: a language used to write a procedure or other description of a computation
queue: a data structure with first-in first-out behavior, supporting the operations enqueue (to insert) and dequeue (to remove)
reduction: a recasting of one problem as another (somewhat different) problem
recursion: a reduction of a problem to another (typically smaller) instance of the same problem
representation invariant: a property that holds true of the internal representation initially and after the completion of each method
semantics: the meaning of an expression
stack: a data structure with last-in first-out behavior, supporting the operations push (to insert) and pop (to remove)
state: stored information (associated with a process)
subclass: a class that extends another class, possibly by adding new methods or overriding existing methods
substitution model: a model of computation in which expressions are successively replaced by their values until a final result is reached
symbol: a name used to denote a value
synchronized: keyword modifying a class or method indicating that internal state is not thread-safe. A lock is automatically generated to protect the data.
syntax: the notation used to express an idea
tail recursion: a form of recursion in which the result of the recursive call is the final answer; no combining is done on the result of the recursive call
termination condition: a predicate that becomes true when a computation ends
top-down refinement: a design technique in which a problem is described at a highly abstract level and then broken down into finer and finer details until all the pieces are filled in
transient: a modifier indicating that the data is not part of an object's persistent state, and thus needs not be serializable
try: a keyword starting a try block, which uses methods that throw Exceptions. These Exceptions must be caught at the end of the try block
volatile: a keyword indicating that the data is used by synchronized threads, telling the compiler not not to attempt optimizations on it