Concerning rules and conventions for naming variables in Java, choose an incorrect statement.

An identifier can begin with any character except 'S and ‘_'

An identifier can begin With a character.

An identifier can begin with the dollar Sign character.

An Identifier can write the underscore character.

What will be the output of the following code snippet? class A { public void methodA() { System.out.println("Class A"); }} class B extends A { public void methodA() { System.out.println("Class B"); } public void methodB() { System.out.println("Class B - methodB"); }} public class Test { public static void main(String[] args) { A obj = new B(); obj.methodA(); }}

Compilation error due to the obj.methodB() line

Which of the following statements is one of the advantages of OOP?

The systems can be easily upgraded from small to large systems.

OOP leads to higher programmer productivity, better software quality, and higher maintenance costs.

OOP language did not allow breaking the program into bit-sized problems that can be solved easily

Which of the following statements related to the constructors is false?

The constructor can be overridden.

The constructor can be overloaded.

The 'this' keyword and 'super' keyword can be used in the constructor.

Which of the following statements related to the protected access modifier is true?

It allows the outside package access

It does not allow within-package access

The protected members must be initialized before use

What is a superclass in Java inheritance?

The class from which the subclass is derived

The class that inherits from another class

The final class in the inheritance chain

The class that has abstract methods

What is the purpose of the 'super' keyword in Java?

To call the constructor or methods of the parent class

To call the constructor or methods of the child class

To call the members of the same class

What is the primary purpose of using a superclass and subclass relationship in Java?

To achieve code reusability and facilitate polymorphism.

To restrict access to certain methods or fields.

To create multiple instances of a class.

To implement multiple inheritance.

Choose multiple correct answers.

private access modifier should be used for a variable or method to only be accessed within the same class

public access modifier should be used for a variable or method that should be accessible from any class, regardless of the package

protected access modifier should be used for a variable or method that should only be accessed within the same class and subclasses, in the same package

default (no modifier) access modifier only allows access in the same class

What is the "instanceof" operator used for?

To check whether an object is an instance of a particular class or not

To create a new instance of a class

To compare two objects for equality

Choose the correct statement about overloading in Java.

Overloading is based on having multiple methods with the same name but different by the number of input parameters or type of input parameters, or a mixture of both.

Overloading is based on having multiple methods with the same name.

Overloading is based on having multiple methods with the same name, parameter types, and number of parameters.

Overloading is based on having multiple methods with the same name but different return types.

Which of the following statements is correct for a declaration of the interface named MyInterface?

interface MyInterface{/* something */}

public MyInterface interface{/* something */}

final interface MyInterface{/* something */}

default interface MyInterface {/* something */}

Consider an abstract class "Shape" with an abstract method "calculateArea()." If a concrete subclass "Circle" extends "Shape" and provides an implementation for "calculateArea()," what happens when an object of the "Circle" class is created and the "calculateArea()"

The concrete method in the subclass is executed.

Both the abstract method in the superclass and the concrete method in the subclass are executed.

The abstract method in the superclass is executed.

An exception is thrown at runtime.

Choose the correct statement about the anonymous class.

An anonymous class can be used to implement an interface

Anonymous class used to extend methods

Anonymous class is used to define a set of constants

Which of the following is the best description of polymorphism?

It is the ability for a message/data to be processed in more than one form.

It is the ability for many messages/data to be processed in one way

It is the ability for a message/data to be processed in only one form

You are tasked with implementing a system that tracks the frequency of words in a large text document. Explain how you would use a Java collection to efficiently achieve this, emphasizing the principles of abstraction and encapsulation.

Utilize a HashMap<String, Integer> for efficient word frequency tracking.

Implement a LinkedList<String> to store words and their occurrences.

Use a Priority Queue<String> to prioritize words based on frequency.

Employ a HashSet<String> for unique word storage.

Utilize a TreeMap<String, Integer> for a sorted mapping of words and frequencies.

In a financial application, you need to store unique customer IDs efficiently, ensuring rapid lookup and insertion. Describe the Java collection you would choose, the reasons behind your choice, and how you would handle potential duplicates.

Utilize a LinkedHashSet<Integer> to maintain insertion order while ensuring uniqueness.

Choose a TreeSet<Integer> to automatically handle duplicates and ensure quick lookups.

Implement a custom CustomerIDManager class with an embedded array for efficient management.

Design a HashMap<Integer,Boolean> where uniqueness is enforced through key existence.

Use a BitSet to represent customer IDs with efficient storage.

In a logistics application, you need to associate each product with its corresponding warehouse location. Illustrate how you would use a Java collection to model this relationship, considering the principles of association and key-value mapping.

Use a HashMap for direct key-value mapping.

Utilize a LinkedHashMap to maintain insertion order.

Implement a custom ProductWarehouseAssociation class with parallel arrays.

Choose a HashSet for efficient storage of associations.

Design a TreeMap for sorted key-value mapping.

Which of the following objects is a parameter of the constructor of the DataInputStream class?

An object of the FileInputStream class

An object of the BufferedReader class

An object of the Random AccessFile class

Which of the following statements about the low-level stream and the high-level stream is true?

The low-level stream's data unit is a byte, high-level stream's data unit is a primitive type.

The low-level stream's data unit is character UTF-8, high-level stream's data unit is character UNICODE

The low-level stream's data unit is a character type, high-level stream's data unit is an object type.

The low-level stream's data unit is primitive, high-level stream's data unit is character.

Which of the following statements is used to add the content to an existing text file?

Set the append parameter to true in the constructor of the FileWriter object

Set the append parameter to true in the constructor of the File object

Set append parameter of true in the constructor of OutputStream object

Java Language Quiz

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50 questions

Which of the following statements about the Java language is true?

What is the purpose of a Java Virtual Machine(JVM)?

Which of the following statements is used to compile the program.java file?

Which is a valid keyword in Java?

Which of the following concepts does not belong to object-oriented programming features?

Which of the following is NOT a Java feature?

A Java source code will be compiled to the file in which of the following extensions?

Which of the following is a primitive data type in Java?

which of the following is a Java primitive type?

Concerning rules and conventions for naming variables in Java, choose an incorrect statement.

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