Object-Oriented Analysis and Design (OOA&D) Quiz

8 Questions

Explain the difference between Java and C++ in the context of object-oriented programming language.

Java is a purely object-oriented programming language, whereas C++ is a hybrid language that supports both procedural and object-oriented programming.

What are the different types of variables in Java?

The different types of variables in Java include local variables, instance variables, and class variables (static variables).

Define and explain the usage of constructors in Java.

Constructors in Java are special methods used for initializing objects. They have the same name as the class and do not have a return type. Constructors are called when an object of a class is created.

What is the purpose of the 'finalize' method in Java, and how does it relate to garbage collection?

The 'finalize' method is used to perform cleanup processing just before an object is garbage collected. It is called by the garbage collector prior to collecting the object's memory.

What are static variables and methods in Java, and how are they different from instance variables and methods?

Static variables and methods belong to the class rather than to individual instances of the class. They are shared among all instances of the class and can be accessed using the class name. Instance variables and methods, on the other hand, are unique to each instance of the class.

Explain the concept of method overloading in Java.

Method overloading in Java refers to the ability to define multiple methods with the same name in a class but with different parameters. This allows for flexibility in calling methods with different argument lists.

What is dynamic method dispatch in Java?

Dynamic method dispatch in Java refers to the mechanism by which the correct implementation of an overridden method is determined at runtime. This allows for polymorphic behavior when dealing with objects of different subclasses.

How is the 'static' keyword used before variables and methods in Java?

In Java, the 'static' keyword is used to create class-level variables and methods, which are shared among all instances of the class. This means that the variable or method is associated with the class itself rather than with any specific instance.

Study Notes

Java vs C++ in Object-Oriented Programming

Java and C++ are both object-oriented programming languages, but Java is more focused on platform independence, simplicity, and ease of use, while C++ is more focused on performance, control, and flexibility.

Types of Variables in Java

Primitive variables: store single values (e.g., int, boolean, char)
Reference variables: store references to objects (e.g., String, arrays)
Array variables: store collections of values or objects

Constructors in Java

A constructor is a special method that initializes an object when it's created
Constructors have the same name as the class and no return type (not even void)
They are used to set initial state of an object and ensure it's in a valid state
Constructors can be overloaded, just like methods

Finalize Method and Garbage Collection

The finalize method is a special method that is called by the garbage collector before an object is destroyed
It's used to release resources, such as file handles or sockets, that the object has acquired
The finalize method is called only once, just before the object is garbage collected

Static Variables and Methods

Static variables belong to the class, rather than instances of the class
Static methods belong to the class, rather than instances of the class
Static members are shared by all instances of the class
Static methods can only access static members

Method Overloading

Method overloading is when multiple methods have the same name but different parameter lists
The method that gets called is determined by the number and types of arguments passed
Method overloading allows for more flexibility and readability in code

Dynamic Method Dispatch

Dynamic method dispatch is when the method to be called is determined at runtime, rather than compile time
It's used to implement polymorphism, where objects of different classes can respond to the same method call
Dynamic method dispatch is achieved through method overriding and method overloading

Static Keyword

The static keyword is used to declare static variables and methods
Static variables are shared by all instances of a class
Static methods can be called without creating an instance of the class
Static members are initialized only once, when the class is loaded