Java 2 chapter 9
derived class
a class that inherits from a base class.
base class
a class that is used as a basis for inheritance.
containment
the relationship between classes when one class contains fields that are members of another class. See has-a relationship, composition, and aggregation.
subclass
a base class.
superclass
a base class.
child class
a derived class.
aggregation
a type of containment in which a class contains one or more members of another class that would continue to exist without the object that contains them.
parent class
a base class.
extends
a keyword used to achieve inheritance in Java.
upcast
to change an object to an object of a class higher in its inheritance hierarchy.
subtype polymorphism
the ability of one method name to work appropriately for different subclasses of a parent class.
super
a Java keyword that always refers to a class’s immediate superclass.
protected access
describes an intermediate level of security between public and private; a class’s protected members can be used by a class and its descendants, but not by outside classes.
@Override annotation
a directive that notifies the compiler of the programmer’s intention to override a parent class method in a child class.
fragile
describes classes that are prone to errors.
inlining
an automatic process that optimizes performance by replacing calls to methods with implementations.
virtual method calls
method calls in which the method used is determined when the program runs, because the type of the object used might not be known until the method executes.
abstract class
a class from which no concrete objects can be instantiated, but which can serve as a basis for inheritance. Abstract classes usually have one or more empty abstract methods. Contrast with concrete class.
concrete class
a nonabstract class from which objects can be instantiated. Contrast with abstract class.
virtual class
the name given to an abstract class in some other programming languages, such as C++.
nonabstract method
a method that is given a body.
abstract method
a method declared with the keyword abstract and that has no body; a subclass must override each base class abstract method.
dynamic method binding
the ability of an application to select the correct subclass method when the program executes. See also late method binding.
static method binding
the opposite of dynamic method binding; occurs when a subclass method is selected while the program compiles rather than while it is running. See also fixed method binding.
late method binding
the ability of an application to select the correct subclass method when the program executes. See also dynamic method binding.
fixed method binding
the opposite of dynamic method binding; occurs when a subclass method is selected while the program compiles rather than while it is running. See also static method binding.
ad-hoc polymorphism
polymorphism that occurs when a single method name can be used with a variety of data types because various implementations exist; another name for method overloading.
pure polymorphism
the situation in which a single method implementation can be used with a variety of related objects because they are objects of subclasses of the parameter type. See also inclusion polymorphism.
inclusion polymorphism
the situation in which a single method implementation can be used with a variety of related objects because they are objects of subclasses of the parameter type. See also pure polymorphism.
Object class
a class defined in the java.lang package that is imported automatically into every Java program; every Java class descends from the Object class.
multiple inheritance
the capability to inherit from more than one class; Java does not support multiple inheritance.
hash code
a calculated number used to identify an object.
interface
a construct similar to a class, except that all of its methods must be abstract and all of its data (if any) must be static final; it declares method headers, but not instructions within those methods.
record
Definition:
a keyword that defines an immutable class that requires only field definitions.
functional interface
an interface that contains just one abstract method.
lambda operator
operator used in a lambda expression that is composed of a minus sign and greater-than sign.
anonymous inner class
a class that has no name and is defined inside another class.
lambda expression
an expression that creates an object that implements a functional interface.
effectively final variable
a variable whose value is assigned only once.