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M250 Java book 3
Open Uni M250 Object Oriented Java Programming Book 3 (units 9-12)
| Term | Definition |
|---|---|
| absolute pathname | A full path to a file beginning from the name of the storage device. |
| array | An indexable, fixed-size collection whose elements are all of the same type. |
| array initialiser | An expression that can be used to initialise an array using assignment, a shortcut way of initialising array elements. |
| auto-boxing | This is the automatic process of wrapping primitive values when called for by the context of usage in a Java program. |
| auto-unboxing | This is the automatic process of unwrapping primitive values when called for by the context of usage in a Java program. |
| bucket | A data structure that can contain zero or more unsorted elements. A HashSet uses buckets to implement a set. The hash code of each incoming element is used to decide which bucket to store it in. |
| buffer | Could refer to either an area used for temporary storage as data is transferred between a data source and a data sink, or a sequence of unfilled components that allows a StringBuilder object to grow. |
| bulk operations | Operations that act on an entire collection without requiring the programmer to focus on individual elements. |
| capacity | The number of characters a StringBuilder object can hold. |
| collection | A collection consists of a number of, possibly zero, objects or primitives. The objects or primitives within a collection are referred to as elements. |
| Collection Classes | A set of library classes used to create various kinds of collection such as tree structures and queues. When capitalised, this phrase usually refers to classes that are part of Java's Collections Framework, which excludes array types. |
| collection classes | A set of library classes used to create various kinds of collection such as tree structures and queues. When used in lower case, this phrase generally means any class that implements a collection, which includes array types. |
| Collections Framework | This includes a set of collection interfaces, a set of collection classes that implements them and some supporting utility classes. It also includes a set of associated recommendations about constructors and expected behaviours in common. |
| comma-delimited file | A file whose items of date are separated by commas. |
| Comparable | An interface that allows an element type to be sorted. It contains a single method: compareTo() |
| compareTo() | The sole method of the Comparable interface. Allows classes of objects implementing this interface to be sorted. |
| component (of an array) | The memory location at which an element of an array is stored. |
| component type | The type of the components of an array object; this determines the types of the object or primitive value that can be stored in the array. |
| destructive operation | An operation on a collection that changes the contents in some way is said to be destructive. It is not always obvious whether a method is destructive or non-destructive. |
| diamond operator | From Java 7 onwards the diamond operator, written <>, simplifies the construction of collection objects. The compiler uses type inference to determine the appropriate type of the collection based on the type of the collection's reference variable. |
| difference | For sets, the difference of A and B is all the elements in A that are not in B. This result is usually different from the difference of B and A. The term is used to refer both to the result and to the operation. |
| effective length | The number of meaningful elements that a fixed size collection actually holds. |
| element | The name given to the primitive value stored in, or the object referenced by, an array component. |
| entry | An entry in a map means a key-value pair; that is, it refers to the combination of a key and its associated value. |
| equals() | A method that determines whether two objects are equal or not. Since it is implemented by the class Object, all classes of object understand the message equals() but the method is overridden to define versions of equality appropriate to particular classes |
| File | An instance of this class contains the pathname to a file or folder in a system-independent format. The file specified need not exist; instead the pathname may point to a potential new file or folder. |
| finally | Java keyword that introduces a block of code in a try-catch statement that will always be executed, regardless of whether an exception occurs or not. |
| fixed size collection | A collection whose number of elements is fixed on creation. Such a collection can neither grow nor shrink. |
| flushing | The process of emptying a buffer so that no data remains in it, the data being transferred to a sink. |
| for-each statement | A statement that enables iteration through every element of a collection. |
| generics | A programming language feature that allows the writing of code that supports many types, but allows a particular type to be specified, so allowing for more type checking to take place. |
| hash code | A hash code is an int that can be calculated for any object by sending it the message hashCode(). Inherited from Object, generally must be overridden if equals() has been overridden. Used by sets and related collections to check rapidly for duplicates. |
| homogeneous collection | A collection in which all the elements are of the same type. All collections in Java are homogeneous. |
| identity | Identity refers to an object rather than its state. Two reference variables have the same identity if they both reference the same object; that is, if they both contain a copy of the same reference value. |
| immutable | An object whose state cannot be changed. An object whose state can be changed is said to be mutable. |
| implementation class | A class that implements an interface, also known as an implementing class. |
| implementing class | In the context of collections an implementing class is a class that implements a particular collection interface. |
| index | An integer that is used to access the elements of an indexable collection. |
| indexable collection | A collection in which every element is accessed by an index |
| InputStream | The base class of a hierarchy of classes including FileInputStream, BufferedInputStream and ObjectInputStream, which are used to read (8-bit) byte streams. InputSteam classes are used to read binary data. |
| intersection | Intersection is a mathematical operation on two or more sets that result in a set containing only the elements common to both sets. The term is used to refer both to the result and to the operation. |
| java.util.Arrays | A Java utility class that contains static methods for manipulating arrays. |
| key | A key is a value that can be used to uniquely identify any object from a given map-based collection. What constitutes a good key may depend on the purpose of the collection. |
| key set | The set of all the key values for all the entries in some map. A key set is typically used to iterate over a map-based collection. |
| key-value pair | Maps can be viewed as a set of key-value pairs. Each entry in a map is a key-value pair. |
| length | The number of elements an array can hold. |
| list | An ordered collection of variable size that permits duplicate elements. |
| map | A collection type that relates a set of keys to their corresponding values. |
| mapping | Another name for a key-value pair. |
| natural ordering | An element type is said to have natural ordering if it implements the interface Comparable and consequently has a compareTo() method. For numbers and strings, the natural ordering corresponds to everyday numerical and alphabetical order. |
| non-destructive operation | An operation on a collection that does not change the contents in any way. |
| ordered collection | A collection where each element in the collection has a well-defined place, as indicated by its index number. Thus, an ordered collection allows us to access and find the first, second or last element. Order is determined by where each element is on list |
| OutputStream | The base class of a hierarchy of classes including FileOutputStream, BufferedOutputStream and ObjectOutputStream, which are used to write (8-bit) byte streams. OutputStream classes are used to write binary data. |
| pathname | A textual representation of how to find a file or folder on a particular operating system. |
| persistence | The ability of objects or other data to continue in existence after a program has stopped executing. |
| persistent | Stored in a non-volatile form, that is, a form that is not lost when the computer's power is turned off. The most common form of persistent storage is a file on a disk drive. |
| primary sort | An initial sorting according to a particular key. |
| raw collection | A collection for which an element type is not specified. Java collections prior to Java 5 are raw collections. |
| Reader | The base class of a group of classes including FileReader and BufferedReader, which are used to read 16-bit character streams. Reader classes are used to read text files. |
| relative pathname | A path to a file beginning from the current working directory, often resulting in a shorter path than an absolute path. |
| Scanner | A class used to read string tokens from a source. In M250 the source may be a FileReader or a String. |
| secondary sort | A sorting that can be applied after applying a primary sort in order to sort any elements that are considered equal by the primary sort. |
| set | A collection in which each item may appear only once - no duplicates are allowed. |
| sorted collection | A collection that always keeps its elements in their natural ordering, if any. This contracts with an ordered collection, where the ordering may just be an accident of where elements happen to have been placed. |
| stable sort | A sort that does not reorder equal elements. |
| stream | An object used to connect a data source to a data sink, enabling data to be transferred from the source to the sink. |
| string interning | A process used by Java to create a pool of strings that can be reused when possible, which may result in the sharing of string literals. |
| StringBuilder | A class whose instances represent a mutable sequence of characters. |
| sub-array | A set of contiguous components within the same array. |
| subinterface | A subinterface is an interface that extends another interface (called its superinterface) thereby inheriting the signatures of the parent interface, and which typically contains additional method signatures. |
| sublist | A list together with any two positions in the list may be seen as defining a new list containing just those elements between the two positions, retaining the same order. The new list is known as a sublist. |
| superinterface | A superinterface is an interface that is extended by some other interface(s). |
| token | An item of data that can be written to or retrieved from a file. Delimiters are used to separate tokens in a file. |
| tree | A collection structure typified by branching connections between elements, often used to create collections of items sorted according to some criteria. |
| union | Union is a mathematical operation on two or more sets that results in a set containing all of the elements of all of the sets. The term is used to refer both to the result and to the operation. |
| unwrapping | The process of converting a wrapped value (one contained in a wrapper class) to its primitive value equivalent. |
| wrapper class | Every primitive type has a corresponding wrapper class whose purpose it is to hold a primitive value in place where a primitive value is intuitively what is needed but where the type checking requires an object. |
| wrapping | The process of converting a primitive value to an object equivalent, using a wrapper class. |
| Writer | The base class of a group of classes including FileWriter and BufferedWriter, which are used to write 16-bit character streams. Writer classes are used to write text files. |
| zero-based indexing | An indexing system in which the first index is 0. |
Created by:
Annelien
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