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A template for creating objects which describes both the data known by each object and the methods which operate on those data.
A particular kind of data item, as defined by the values it can take, the programming language used, or the operations that can be performed on it (Oxford University, 2013). Also: data type.
The combination of data and the operations that act on the data to form a single program unit called an object (IBO).
A variable in which an object stores a value representing an aspect of the object’s state. Formally: an instance field.
An example or single occurrence of something; ex: a serious instance of corruption; the search finds every instance where the word appears (Oxford University, 2013).
1: An object’s state has integrity when every one of the object’s fields contains a valid value.
2: A programmer’s solemn obligation is to ensure the integrity of an object’s state.
A subprogram which performs a task (like a procedure) or returns a value (like a function). Instance methods are called against (invoked against) an instance of a class (an object). Static methods have no implicit parameters; that is to say, they are not called against an object.
method signature
The header of a method which specifies its access level, name, return type, and parameters (if any).
Operator required for instantiation of a class. Requires a single postfix argument: a constructor call. Performs three actions: (1) allocates memory for a new object, (2) invokes the object constructor, (3) returns a reference to the allocated memory (Creating Objects, n.d.)
“the reserved constant used in Java to represent a void reference— i.e.: a pointer to nothing” (Green, Roedy. null: Java Glossary. Retrieved 2013-09-25.).
1: An instance of a class created by the process of instantiation.
2: A specific set of data and the methods for their manipulation. Every object has knowing responsibilities and doing responsibilities.
3: A representation or model of an entity in the “real world.”
When the same name is used for more than one method, the name is overloaded. This is particularly common for constructors, because all constructors must have the same name: the name of the class. Overloaded methods have the same name but different parameters: different in datatype and/or listed in different order (Horstmann, 2002).
Operators can also be overloaded. For example: “+” means addition in one context, positive in another, and concatenation in yet another.
The principle that the action of a method depends on the datatype of the object against which the method is invoked. For example, the same method may have a different action on an object of a subclass than on an object of the corresponding superclass. (See also Polymorphism.)
In BlueJ, a directory which contains the files which comprise a Java program.
The set of values stored in the fields of an object.
1: A method which does not act on an object; a static method; ex: method main does not act on any object.
2: A field which describes the state of a class, not of a particular object; a static field; ex: static final int NEXT_ACCOUNT_NUMBER = 1;
3: A declared constant; ex: static final int ADULT = 1; static final boolean TAXABLE = true;
“The set of rules that defines the combinations of symbols that are considered to be a correctly structured document or fragment in [a programming] language.” (Syntax (programming languages), 2016).
1: A reference to the current object (Oracle. Using the this Keyword. Retrieved 2016-01-01).
2: A reference to the implicit parameter.


Creating Objects. (n.d.). Retrieved September 18, 2016, from

Horstmann, C. (2002). Big Java. John Wiley & Sons, Inc. ISBN 0-471-40248-6.

Oxford University. (2013). New Oxford American Dictionary. NY: Oxford University Press [application].

Syntax (programming languages). (n.d.). In Wikipedia. Retrieved September 5, 2016, from > Education Commons > Java > Resources

[This page last updated 2020-12-23 at 12h13 Toronto local time.]