Exam Prep S.E.

What do anonymous classes represent in Java?

Classes defined inside other classes that cannot be instantiated

Classes defined inside methods or blocks from methods that are only visible locally

Classes defined inside other classes and do not have a certain name

Classes that dissapear after the program compiles the first time

What is the main difference between AWT and Swing in Java?

AWT is faster than Swing

Swing offers a richer set of graphical components

Swing is not Java-compatible

AWT is easier to learn than Swing

What is the use of the setContentPane() method in Java Swing?

Sets the window dimensions

Adds a container in a window

Sets the main content of a window

Activates click events

What is the role of the wait() method?

Awaits a notification from another execution thread

Prints the message "I was notified"

Enters an infinite loop

Waits for 2 seconds

Which of the following mechanisms are used to synchronize threads of execution in Java?

Wait/notify

Synchronized

Join

Sleep

Which of the following methods is used to add a component to a container in Java Swing?

AppendComponent(component);

Add(component);

AddComponent(component);

InsertComponent(component);

What in an enum in Java?

A type of data used for simplifying constant declaration

A type of class that cannot be instantiated

A type of variable used to store email adresses

A name by which we refer to arrays that count certain elements

What is serialization in Java?

A process of converting an object into a byte flux used to save and send objects

A process of converting a data type in another data type used for manipulating values

A process of encryption for data in Java

A process through which you give your program a unique serial number

What is the difference between abstract methods and final methods in Java?

Abstract methods cannot be overwritten, while final methods cannot be accesed from other classes.

Abstract methods do not have implementations, while final methods cannot be overwritten

Abstract methods are only used in abstract classes, while final methods are only used in final classes

Abstract and final methods do not have any differences

What is an abstract class in Java?

A class that cannot be instantiated

A class that cannot be inherited

A class that cannot have other methods

An instance of an interface

What is an interface in Java?

An abstract class

A collection of variables

A collection of abstract methods

A collection of objects

What is polymorphism in Java?

The ability to create new objects from existing objects

The ability to extend the functionality of an existing class

The ability to split a class into multiple parts

The ability to use the same method in multiple different classes

What is inheritance in Java?

The ability to create new objects from existing objects

The ability to extend the functionality of an existing class

The ability to split a class into multiple parts

The ability to create a collection of similar objects

What is a class in Java?

A primitive data type

A method used for creating objects

A collection of similar objects

A template for creating objects

What do exceptions represent in Java?

The mechanism used for treating errors while the program is being executed

Events generated and solved while compiling the programs

Special classes used for managing object collections

Events generated by the operating system

What does the List class represent in Java Collection Framework?

An element collection that does not allow duplicates

An element collection that allows duplicates

A key-value pair collection

A collection of ordered elements

What do synchronous and asynchronous messages represent in a sequence diagram?

Synchronous messages - messages that wait for a response; asynchronous messages - messages that do not wait for a response

Synchronous messages - messages that do not wait for a response; asynchronous messages - messages that wait for a response

Synchronous messages - messages sent between the same object; asynchronous messages - messages sent between different objects

Synchronous messages - messages that can only be sent between objects of the same class; asynchronous messages - messages sent between objects of different classes

Which is the distinctive characteristic of a Map?

Contains ordered elements

Does not allow duplicate values

Stocks pair of type key-value

Implements a stack-type structure

What happens after a Java program throws an exception?

The program continues to run normally

The execution of the program is stopped and it shows an error message

It shows an error message, but the execution of the program continues

A certain action defined in the "Catch" block happens

What is the meaning of the following relationship in the UML diagram? (A and B are classes)

Composition (B has an attribute of type A)

A extends B

Aggregation (A has an attribute of type B)

Association (B has an attribute of type A)

What is the meaning of the following relationship in the UML diagram? (A and B are classes)

Association ( A has an attribute of type B)

A extends B

Aggregation (B has an attribute of type A)

Composition (A has an attribute of type B)

What is the meaning of the following relationship in the UML diagram? (A and B are classes)

A depends on B

A extends B

B implements A

Aggregation (A has an attribute of type B)

What is the purpose of using buffers in input/output streams?

Reduce unnecessary network traffic

Increase the efficiency of reading and writing data

Allow working with encrypted files

Eliminate the need for try-catch blocks in exception handling code

What is the role of a layout manager in graphical interfaces in Java?

Managing the arrangement of graphical components on the page

Validating and processing user inputs

Displaying user data

All of the above

Which of the following classes is used for event handling in Java Swing?

ActionListener

MouseEvent

KeyListener

All of the above

What is the main purpose of the Model-View-Controller (MVC) in graphic interfaces?

Separation of concerns and flexible coupling of components

Displaying user data

Processing user inputs

All of the above

The keyword volatile is used to

Ensure that variables cannot be accessed in multiple threads

Ensure that shared variables are consistenly updated by multiple threads

Create variables that are lightweight

Create lightweight classes

The keyword synchronized is used to:

Implement mutual exclusion

Ensure that a method is executed simultaneously on multiple threads

Create synchronous variables

Ensure that two Java applications start at the same time

What method from class Thread should be overriden in order to implement the logic of a new thread?

Start();

Run();

Runtime();

Synchronized();

What is ObjectOutputStream used for?

To serialize objects

To deserialize objects

To read from text file

To write into text files

What type of exception is ArrayIndexOutOfBoundsException?

Unchecked (runtime) exception

Checked (compile time) exception

Error

Random exception

What type of Map stores the objects in the order in which they are inserted?

HashMap

LinkedHashMap

TreeMap

AdditionOrderedMap

What is the design pattern prototype used for?

To ensure a class cannot be extended

To ensure a class cannot be instantiated

To ensure a class can be instantiated only once

To clone existing objects when objects creation is expensive

What is the design pattern Factory used for?

It is used to instantiate classes that have lots of attributes

It is used to instantiate classes that have a single attribute

It is used in industrial Java applications

It is used to hide the complex creation factor from client code

What is the meaning of the keyword void in Java?

The method has no parameter

The method doesn't return anything

The method returns null

The method returns 0

Consider two String variables a and b. How do you correctly verify that their values are equal in Java?

A.equals(b);

A=b;

A===b;

A.eq(b);

How do you correctly declare and instantiate an array of 10 integers in Java?

int [10];

Int[] v = new int[10];

Int[] v = new int[9];

Int[] v;

What is the role of the word "this"?

Refers to the current object

Declares a class variable

Refers to the constructor of the base class

Helps access the common interface of objects

What is the role of the word "super"?

Refers to the current object

Allows referencing members from the base class

Is used to declare super-classes

Helps access the common interface of objects

What do you understand by method overloading?

A sequence of code that forces the processor

Multiple methods with the same name and different parameter lists

Forced modification of static variables

Modifying an inherited method

The final keyword is used for:

Declaring volatile variables

Declaring constants

Declaring classes that cannot be extended (inherited)

Declaring methods that cannot be overridden

The static keyword is used for:

Declaring instance members

Declaring class members

A static member cannot be modified

A static variable is not collected by the garbage collector

Consider the following code sequence: int[] arr = {1, 2, 3, 4}; System.out.println(arr[1]); In the console, the output will be:

An asbtract class can have:

Only methods with implementation

Only methods without implementation

Both methods with implementation and methods without implementation

Cannot have methods, only abstract attributes

Starting with Java 8, an interface can have:

Only methods with implementation

Only methods without implementation

Both methods with implementation and methods without implementation

There are no interfaces in Java

Which of the following blocks is always executed, regardless of whether an exception is thrown or not?

Try

Catch

Throw

Finally

Where is a method declared in an interface visible by default (without any access specifier)?

Only inside the interface (private)

In all classes from all packages (public)

Only in the current package (package)

Only in the current package and in the classes that implement the interface

Which design pattern is used mostly in the context of graphical interfaces?

Singleton

Factory

Model-View-Controller

Prototype

Which type of exceptions does not require mandatory handling (try-catch OR throws) to compile Java code?

Runtime exceptions

Compile-time exceptions

Explicit handling of all exceptions is mandatory

No exception handling is mandatory to compile a Java application

Which design pattern is used for cloning existing objects when instantiation is expensive?

Singleton

Factory

Iterator

Prototype

Exam Prep S.E.

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