Object Oriented Programming Using Java

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Unit 1 - Basics of Java and Strings in Java

Email *

Record my email address with my response

Full Name:(Format : FirstName MiddleName LastName) *

Division *

Roll No. *

Java Runtime Environment (JRE) is responsible for: *

1 point

A. Compiling Java code

B. Running Java applications

C. Debugging Java programs

D. Writing Java documentation

Which of the following is NOT true about Oracle JDK and OpenJDK?
*

1 point

A. Oracle JDK is the official implementation of Java, while OpenJDK is an open-source implementation.

B. Both Oracle JDK and OpenJDK provide tools for developing and running Java applications.

C. Oracle JDK is free to use for commercial purposes, while OpenJDK may have some licensing restrictions.

D. OpenJDK is the reference implementation for Java SE platform specifications.

Naming conventions in Java are used for:
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1 point

A. Improving program readability and maintainability

B. Enhancing program performance

C. Controlling access to class members

D. Enforcing security policies

Which of the following is a valid Java naming convention for variables?
*

1 point

A. myVariable

B. my_variable

C. 1variable

D. variable123

What is the recommended convention for naming constants in Java?
*

1 point

A. camelCase

B. UPPERCASE_WITH_UNDERSCORES

C. PascalCase

D. kebab-case

Which of the following is a valid Java class name according to naming conventions?
*

0 points

A. MyClass

B. My_Class

C. myClass

D. MyClass123

What is the naming convention for Java packages?
*

1 point

A. UPPERCASE_WITH_UNDERSCORES

B. PascalCase

C. camelCase

D. lowercase

Which naming convention is commonly used for method names in Java?
*

1 point

A. UPPERCASE_WITH_UNDERSCORES

B. camelCase

C. PascalCase

D. kebab-case

What is the primary purpose of a Java profiler?
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1 point

A. To compile Java source code

B. To debug Java applications

C. To optimize the performance of Java applications

D. To write unit tests for Java classes

Which of the following tasks can a Java profiler help with?
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1 point

A. Identifying memory leaks

B. Generating code documentation

C. Creating graphical user interfaces

D. Managing database connections

Which of the following Java profilers is commonly used for analysing performance bottlenecks in Java applications?
*

1 point

A. Maven

B. Javadoc

C. JProfiler

D. Jenkins

In Java, which keyword is used to declare a variable that can be accessed and modified by any method in the same class, as well as by subclasses?
*

1 point

A. final

B. static

C. public

D. private

What is the scope of a local variable in Java?
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1 point

A. It can be accessed within the same method where it is declared

B. It can be accessed within the same class where it is declared

C. It can be accessed within any method of the same class

D. It can be accessed globally within the entire application

Which of the following data types is NOT valid for declaring a Java variable?
*

1 point

A. int

B. float

C. char

D. void

What is the result of the expression 5 + 3 * 2 in Java?
*

1 point

A. 16

B. 11

C. 13

D. 26

Which operator is used for performing exponentiation in Java?
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1 point

A. ^

B. **

C. %

D. ~

What is the result of the expression true && false in Java?
*

1 point

A. true

B. false

C. Compile-time error

D. Runtime error

Which of the following operators is used to perform string concatenation in Java?
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1 point

A. +

B. -

C. *

D. /

What is a statement in Java?
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1 point

A. A line of code that performs a calculation

B. A block of code enclosed in curly braces {}

C. An instruction that performs an action

D. A conditional expression

What is the purpose of a return statement in Java?

1 point

A. To exit a loop

B. To terminate the program

C. To return a value from a method

D. To declare a variable

Clear selection

What is a block in Java?
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1 point

A. A single line of code

B. A group of statements enclosed in curly braces {}

C. A special type of variable

D. A conditional expression

Which of the following is NOT true about blocks in Java?
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1 point

A. Blocks can be nested within each other

B. Blocks define the scope of variables

C. Blocks can have their own return statements

D. Blocks are always executed sequentially

What is the scope of a variable declared inside a block in Java?
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1 point

A. It can be accessed only within the same block

B. It can be accessed within any block within the same method

C. It can be accessed within any block within the same class

D. It can be accessed globally within the entire application

Which of the following statements is used to execute a block of code repeatedly as long as a condition is true?
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1 point

A. if-else

B. switch

C. while

D. for

In Java, which control flow statement is used to terminate the current iteration of a loop and continue with the next iteration?
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1 point

A. break

B. continue

C. return

D. exit

What is the purpose of the "switch" statement in Java?
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1 point

A. To perform repetitive tasks

B. To define a group of related variables

C. To control the flow of execution based on multiple conditions

D. To define a block of code to be executed if a condition is true

Which class in Java is used for reading input from the keyboard?
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1 point

A. System

B. Console

C. Scanner

D. BufferedReader

Which method is used to print output to the console in Java?
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1 point

A. console.log()

B. print()

C. println()

D. display()

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

A. String

B. Int

C. List

D. Array

What is the size of the "int" data type in Java?
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1 point

A. 4 bytes

B. 8 bytes

C. 2 bytes

D. 1 byte

Which of the following is a reference data type in Java?
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1 point

A. int

B. float

C. double

D. String

Which of the following data types is used to store decimal numbers in Java?
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1 point

A. int

B. long

C. float

D. char

What is an array in Java?
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1 point

A. A collection of objects of different types

B. A data structure used to store key-value pairs

C. A container that holds a fixed number of values of the same type

D. A set of methods for performing mathematical operations

Which of the following statements declares an array of integers named "numbers" in Java?
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1 point

A. int[] numbers;

B. numbers int[];

C. integer numbers[];

D. Array numbers[];

How do you access elements of an array in Java?
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1 point

A. By using the element's index

B. By using the element's value

C. By using a loop

D. By using the length of the array

What is type casting in Java?
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1 point

A. Converting a primitive data type to an object

B. Converting an object to a primitive data type

C. Converting a data type of one size to a data type of a different size

D. Converting a string to a number

Which of the following is an example of implicit type casting in Java?
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1 point

A. int x = 5; double y = x;

B. double x = 5.5; int y = (int)x;

C. int x = 5; String y = Integer.toString(x);

D. String x = "5"; int y = Integer.parseInt(x);

Which operator is used for explicit type casting in Java?
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1 point

A. +

B. -

C. *

D. ( )

What is the result of the expression (int) 5.5 after explicit type casting in Java?
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1 point

A. 5

B. 6

C. 5.5

D. Error

When might you need to use type casting in Java?
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1 point

A. When converting between different data types

B. When performing mathematical operations

C. When accessing elements of an array

D. When working with strings

Which of the following statements correctly declares a String variable named "str" in Java?
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1 point

A. String str = "Hello";

B. String str = new String("Hello");

C. str = "Hello";

D. All of the above

Required

Which method is used to find the length of a String in Java?
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1 point

A. length()

B. size()

C. count()

D. getSize()

What is the purpose of the charAt() method in Java?
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1 point

A. To concatenate two strings

B. To check if a string contains a specified character

C. To retrieve the character at a specified index in a string

D. To compare two strings

What does it mean for a string to be immutable in Java?
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1 point

A. It cannot be printed to the console

B. Its value cannot be changed after it is created

C. It can only contain lowercase letters

D. It can be modified freely

Which of the following statements demonstrates the immutability of strings in Java?
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1 point

A. String str = "Hello"; str = "World";

B. String str = "Hello"; str.concat("World");

C. String str = "Hello"; str.toUpperCase();

D. String str = "Hello"; str.substring(1);

Required

What is the result of the following code snippet?

String str1 = "Hello";
String str2 = str1.concat(" World");
System.out.println(str1);

1 point

A. Hello

B. Hello World

C. World

D. Compile-time error

What is the result of the following code snippet?

String str1 = "Hello";

str1="Hello World";

String str2 = str1.concat(" World"); System.out.println(str1);

1 point

A. Hello

B. Hello World

C. World

D. Compile-time error

Which of the following methods can be used to modify a string in Java without creating a new string object?
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1 point

A. concat()

B. toUpperCase()

C. substring()

D. StringBuilder.append()

What is the purpose of using immutable strings in Java?
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1 point

A. To improve performance

B. To reduce memory usage

C. To ensure thread safety

D. All of the above

Which of the following statements correctly declares a StringBuffer variable named "sb" with an initial capacity of 16 characters in Java?
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1 point

A. StringBuffer sb = new StringBuffer(16);

B. StringBuffer sb = new StringBuffer("16");

C. StringBuffer sb = new StringBuffer();

D. StringBuffer sb = "16";

What is the purpose of the append() method in the StringBuffer class in Java?
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0 points

A. To insert a character or string at a specified index

B. To add characters or strings to the end of the buffer

C. To replace characters in the buffer with a specified string

D. To delete characters from the buffer

Which method is used to reverse the characters in a StringBuffer object in Java?
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1 point

A. reverse()

B. append()

C. substring()

D. delete()

What is the key difference between StringBuffer and StringBuilder in Java?
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1 point

A. StringBuffer is synchronized, while StringBuilder is not

B. StringBuilder is synchronized, while StringBuffer is not

C. StringBuffer is immutable, while StringBuilder is mutable

D. StringBuilder is immutable, while StringBuffer is mutable

What is the purpose of the insert() method in the StringBuilder class in Java?
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1 point

A. To reverse the characters in the StringBuilder object

B. To add characters or strings at a specified index

C. To remove characters from the StringBuilder object

D. To replace characters in the StringBuilder object with a specified string

Which method is used to delete characters from a StringBuilder object in Java?
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1 point

A. delete()

B. append()

C. reverse()

D. insert()

What is the output of following Java program?

import static java.lang.System.*;

public class HelloWorld1 {

public static void main(String[] args) {

out.println("Hello, World!");

}

1 point

Compile Time Error

Run Time Error

Hello, World!

None of These

Required

What is the result of the following expression:

boolean result = (5 > 3) && (4 <= 6);

1 point

A. true

B. false

C. Compile-time error

D. Runtime error

What is the result of the following expression:

int x = 10;
int y = 5;
int result = x++ - --y * 2;

1 point

A. 5

B. 10

C. 15

D. 2

Which of the following operators has the lowest precedence in Java?
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1 point

A. Addition (+)

B. Multiplication (*)

C. Unary minus (-)

D. Assignment (=)

Which of the following operators has the highest precedence in Java?
*

1 point

A. Addition (+)

B. Multiplication (*)

C. Unary minus (-)

D. Assignment (=)

What is the result of the following expression in Java:

int x = 5;
int y = ++x;

1 point

A. x = 5, y = 5

B. x = 5, y = 6

C. x = 6, y = 5

D. x = 6, y = 6

What is the result of the following expression in Java:

int x = 5;
int y = 10 - --x;

0 points

A. x = 4, y = 6

B. x = 4, y = 5

C. x = 5, y = 6

D. x = 5, y = 5

What is the value of x after the following code snippet executes in Java:

int x = 5;
int y = x--;

1 point

A. 4

B. 5

C. 6

D. 7

Which of the following statements about pre-increment and post-increment operators in Java is true?

1 point

A. Pre-increment operator returns the incremented value and then increments the variable

B. Post-increment operator increments the variable and then returns the incremented value

C. Both pre-increment and post-increment operators return the incremented value before incrementing the variable

D. Both pre-increment and post-increment operators increment the variable before returning the incremented value

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