40 Questions
What is a class that inherits called?
Derived class
What is the central theme in object-oriented programming and languages that support it?
Inheritance
What are subprograms that define operations on objects called?
Methods
What allows new classes to be defined in terms of existing ones in object-oriented programming?
Inheritance
What is a characteristic of a nested class in Java?
It is hidden from all classes in its package, except for the nesting class
What is true about dynamic binding in Java?
It is the normal way to bind method calls to method definitions
What is a storage structure for instance variables in Java?
Class instance records (CIRs)
What is the purpose of reflection in a programming language?
Allows programs to have runtime access to their types and structure
What does the getClass method of Class return in Java?
The Class object of an object
What does the Method class's invoke method do in Java?
Executes the method found by getMethod
What is a downside of reflection in Java?
Performance costs
What are the major design issues involved in object-oriented programming (OOP)?
Exclusivity of objects, subclasses and subtypes, type checking and polymorphism
What is a characteristic of Java as a programming language?
It supports only OOP
What is a use case of reflection in software tools?
Class browsers need to enumerate the classes of a program
What does the getMethods method of Class return in Java?
An array of all public methods of a class
What is a limitation of reflection in Java?
Some reflection code may not run under a security manager, making code nonportable
What is the entire collection of methods of an object called?
Message protocol
How can a class modify an inherited method?
By overriding the inherited method
What are the two kinds of variables in a class?
Class variables and instance variables
What does dynamic binding allow?
Polymorphic variables to reference objects of the class and its descendants
What does an abstract class include?
At least one abstract method and cannot be instantiated
What are the design issues for OOP languages?
Exclusivity of objects, single and multiple inheritance, object allocation and deallocation, dynamic and static binding, nested classes, and initialization of objects
What is the relationship of subclasses to their parent class?
"is-a" relationship
What is a disadvantage of Multiple Inheritance?
Creating interdependencies among classes that complicate maintenance
Where can object allocation and deallocation occur?
Anywhere if objects behave like ADTs and can be explicitly created on the heap
What should be considered for efficiency?
Dynamic and static binding
What does an abstract method not include?
A definition
What can multiple inheritance allow a new class to inherit from?
Two or more classes
Which language supports multiple inheritance and dynamic binding through virtual methods and pure virtual functions?
C++
Which language has a category that provides some benefits of multiple inheritance through interfaces?
Java
Which language allows reexportation to make a member visible in a subclass, even if it was originally inaccessible due to private derivation?
C++
Which language explicitly calls the finalize method when the garbage collector is about to reclaim the storage occupied by the object?
Java
Which language requires the programmer to decide at design time which methods will be statically bound and which must be dynamically bound?
C++
Which language has wrapper classes for primitive types and allocates objects heap-dynamically with new?
Java
Which language supports single inheritance and dynamic binding for all messages unless the method is final or static?
Java
Which language provides elaborate access controls to class entities such as private, public, and protected?
C++
Which language has a mixed typing system, constructors, destructors, and elaborate access controls to class entities?
C++
Which language allows subclassing to be declared with access controls such as private or public, defining potential changes in access by subclasses?
C++
Which language disallows overriding and allows static binding for methods that are final or static?
Java
Which language has differences in support of OOP, with extensive access controls, multiple inheritance, and dynamic binding?
C++
Study Notes
OOP Support in C++ and Java
- C++ is an OOP language evolved from C and SIMULA 67, featuring mixed typing system, constructors, destructors, and elaborate access controls to class entities.
- In C++, inheritance is supported, and access controls for members include private, public, and protected.
- Subclassing in C++ can be declared with access controls such as private or public, defining potential changes in access by subclasses.
- In C++, reexportation allows making a member visible in a subclass, even if it was originally inaccessible due to private derivation.
- C++ supports multiple inheritance and dynamic binding through virtual methods and pure virtual functions.
- Dynamic binding in C++ allows calling methods through polymorphic variables and binding to messages.
- C++ provides extensive access controls, multiple inheritance, and requires the programmer to decide at design time which methods will be statically bound and which must be dynamically bound.
- Java, closely related to C++, has all data as objects except primitive types, with wrapper classes for primitive types, and objects are heap-dynamic and allocated with new.
- In Java, single inheritance is supported and an abstract class category provides some benefits of multiple inheritance through interfaces.
- All messages in Java are dynamically bound to methods unless the method is final or static, which disallows overriding and allows static binding.
- Java's finalize method is implicitly called when the garbage collector is about to reclaim the storage occupied by the object.
- Overall, C++ and Java have differences in support of OOP, with C++ providing extensive access controls, multiple inheritance, and dynamic binding, while Java supports single inheritance and dynamic binding for all messages.
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