Java/Java Testing/C++ UPDATED ACTUAL Exam Questions and
CORRECT Answers
Define polymorphism? - Polymorphism simply means "many forms". In java polymorphism is
acheived through method overloading and overriding.
For example, say you have an Animal class and two sub classes called Lion and Cat class. All
animals make a sound, so lets say there is a make sound method in all of these classes.
When you call the make sound method from a lion object that is stored in an Animal reference, it
would call the make sound method from the Lion Class. That is how you would explain
polymorphism using overriding.
Define Constructors? - A constructor is a member method with the same name as its class. The
constructor is invoked whenever an object of its associated class is created.It is called constructor
because it constructs the values of data members of the class.
What is a Class? - A class is a blueprint for an object
What is an Object? - An instance of a class
What is multiple inheritance? - A class can inherit properties from more than one class which is
known as multiple inheritance.
What are the advantages of inheritance? - Code reusability
Saves time in program development.
What is the difference between an Array and a List? - The main difference between an array and
a list is how they internally store the data. whereas Array is collection of homogeneous elements.
List is collection of heterogeneous elements.
,What is an iterator? - Iterators are like pointers. They are used to access the elements of
containers thus providing a link between algorithms and containers. Iterators are defined for
specific containers and used as arguments to algorithms.
What is this pointer? - It is a pointer that points to the current object. This can be used to access
the members of the current object with the help of the arrow operator.
What are pass by reference and passby value? - Pass By Reference means the passing the address
itself rather than passing the value.
Passby Value means passing a copy of the value to be passed.
What is the Java API? - What is the Java API?
The Java API is a large collection of ready-made software components that provide many useful
capabilities, such as graphical user interface (GUI) widgets.
What is the Java Virtual Machine (JVM)? - The Java Virtual Machine is software that can be
ported onto various hardware-based platforms.
What is variables and then types - Variables is an identifier that denotes a storage location used to
store a data values.unlike constants that remain unchanged during the execution of a program, a
variable may takes different values at different times during the execution of the program.
Instance variables
Class variables
***Class variables only have one copy that is shared by all the different objects of a class,
whereas every object has it's own personal copy of an instance variable**
Local variable
Parameters
, what is dot operator? - The dot operator(.) is used to access the instance variables and methods of
class objects.It is also used to access classes and sub-packages from a package.
Examples :
Person1.age ---------> Reference to the variable age
Define strings? - Strings represent a sequence of characters.The easiest way to represent a
sequence of characters in java is by using a character array.
What is serialization? - Serialization is the process of converting a objects into a stream of bytes.
What are different types of access modifiers? - Access specifiers are keywords that determine the
type of access to the member a class.
Public
Protected
Private
Default
What is an abstract class? - Abstract class is a class which contain one or more abstract methods,
which has to be implemented by sub classes. An abstract class can contain no abstract methods
also i.e. abstract class may contain concrete methods. An abstract class CANNOT be instantiated.
what are class variables - Class variables are global to a class and belong to the entire set of
objects that class creates. Only one memory location is created for each variable
What is the Collection interface? - The Collection interface provides support for the
implementation of a mathematical bag - an unordered collection of objects that may contain
duplicates.
What must a class do to implement an interface? - The class must provide all of the methods in
the interface and identify the interface in its implements clause.
CORRECT Answers
Define polymorphism? - Polymorphism simply means "many forms". In java polymorphism is
acheived through method overloading and overriding.
For example, say you have an Animal class and two sub classes called Lion and Cat class. All
animals make a sound, so lets say there is a make sound method in all of these classes.
When you call the make sound method from a lion object that is stored in an Animal reference, it
would call the make sound method from the Lion Class. That is how you would explain
polymorphism using overriding.
Define Constructors? - A constructor is a member method with the same name as its class. The
constructor is invoked whenever an object of its associated class is created.It is called constructor
because it constructs the values of data members of the class.
What is a Class? - A class is a blueprint for an object
What is an Object? - An instance of a class
What is multiple inheritance? - A class can inherit properties from more than one class which is
known as multiple inheritance.
What are the advantages of inheritance? - Code reusability
Saves time in program development.
What is the difference between an Array and a List? - The main difference between an array and
a list is how they internally store the data. whereas Array is collection of homogeneous elements.
List is collection of heterogeneous elements.
,What is an iterator? - Iterators are like pointers. They are used to access the elements of
containers thus providing a link between algorithms and containers. Iterators are defined for
specific containers and used as arguments to algorithms.
What is this pointer? - It is a pointer that points to the current object. This can be used to access
the members of the current object with the help of the arrow operator.
What are pass by reference and passby value? - Pass By Reference means the passing the address
itself rather than passing the value.
Passby Value means passing a copy of the value to be passed.
What is the Java API? - What is the Java API?
The Java API is a large collection of ready-made software components that provide many useful
capabilities, such as graphical user interface (GUI) widgets.
What is the Java Virtual Machine (JVM)? - The Java Virtual Machine is software that can be
ported onto various hardware-based platforms.
What is variables and then types - Variables is an identifier that denotes a storage location used to
store a data values.unlike constants that remain unchanged during the execution of a program, a
variable may takes different values at different times during the execution of the program.
Instance variables
Class variables
***Class variables only have one copy that is shared by all the different objects of a class,
whereas every object has it's own personal copy of an instance variable**
Local variable
Parameters
, what is dot operator? - The dot operator(.) is used to access the instance variables and methods of
class objects.It is also used to access classes and sub-packages from a package.
Examples :
Person1.age ---------> Reference to the variable age
Define strings? - Strings represent a sequence of characters.The easiest way to represent a
sequence of characters in java is by using a character array.
What is serialization? - Serialization is the process of converting a objects into a stream of bytes.
What are different types of access modifiers? - Access specifiers are keywords that determine the
type of access to the member a class.
Public
Protected
Private
Default
What is an abstract class? - Abstract class is a class which contain one or more abstract methods,
which has to be implemented by sub classes. An abstract class can contain no abstract methods
also i.e. abstract class may contain concrete methods. An abstract class CANNOT be instantiated.
what are class variables - Class variables are global to a class and belong to the entire set of
objects that class creates. Only one memory location is created for each variable
What is the Collection interface? - The Collection interface provides support for the
implementation of a mathematical bag - an unordered collection of objects that may contain
duplicates.
What must a class do to implement an interface? - The class must provide all of the methods in
the interface and identify the interface in its implements clause.
