-
web.groovymark@gmail.com
- December 26, 2024
Question 21
What is the output of System.out.println(“abc”.charAt(1));?
- A. a
- B. b
- C. c
- D. Error
Answer: B
Explanation: The charAt(1) method returns the character at index 1, which is 'b'.
Question 22
Which of the following statements is true regarding arrays in Java?
- A. Arrays can hold primitive types only.
- B. Arrays are fixed in size once created.
- C. Arrays can be multi-dimensional.
- D. Both B and C
Answer: D
Explanation: Arrays in Java are fixed in size and can also be multi-dimensional.
Question 23
What is the purpose of the super keyword?
- A. To call a superclass constructor
- B. To refer to the current object
- C. To create a new object
- D. To define a method
Answer: A
Explanation: The super keyword is used to call a constructor or method from a superclass.
Question 24
What does the default keyword indicate in a switch statement?
- A. A value to be used if none of the cases match
- B. A method that must be implemented
- C. An access modifier
- D. A keyword for creating constants
Answer: A
Explanation: The default keyword is used to specify a block of code that executes if no case matches in a switch statement.
Question 25
What is the purpose of the throws keyword in method declarations?
- A. To catch exceptions
- B. To declare exceptions that may be thrown
- C. To define a method as abstract
- D. To indicate final variables
Answer: B
Explanation: The throws keyword is used in method declarations to indicate that a method may throw exceptions.
Question 26
How can you concatenate two strings in Java?
- A. Using the concat() method
- B. Using the + operator
- C. Both A and B
- D. Using StringBuilder
Answer: C
Explanation: You can concatenate strings using both the concat() method and the + operator.
Question 27
Which of the following is the correct syntax for an enhanced for loop?
- A. for (Type var : collection) { … }
- B. for (var : collection) { … }
- C. for each (var : collection) { … }
- D. for (Type var in collection) { … }
Answer: A
Explanation: The enhanced for loop syntax is for (Type var : collection) { ... }.
Question 28
What does the instanceof operator do in Java?
- A. Checks if an object is an instance of a specific class or subclass
- B. Casts an object to a specified class
- C. Creates a new instance of a class
- D. Compares two objects
Answer: A
Explanation: The instanceof operator checks if an object is an instance of a specific class or subclass.
Question 29
How can you make a variable accessible across multiple classes?
- A. By declaring it as private
- B. By declaring it as public
- C. By declaring it as static
- D. By declaring it as final
Answer: B
Explanation: Declaring a variable as public allows it to be accessible from multiple classes.
Question 30
What is the purpose of a constructor overloading in Java?
- A. To create multiple constructors with different parameter types
- B. To allow creating an object without parameters
- C. To improve performance
- D. All of the above
Answer: D
Explanation: Constructor overloading allows multiple constructors with different parameter types, including default constructors without parameters.
Question 31
Which of the following statements is used to declare a package in Java?
- A. package com.example;
- B. import com.example;
- C. class com.example;
- D. namespace com.example;
Answer: A
Explanation: The package statement is used to declare a package in Java.
Question 32
How do you throw an exception manually in Java?
- A. throw new Exception(“Error message”);
- B. throw Exception(“Error message”);
- C. raise Exception(“Error message”);
- D. new Exception(“Error message”);
Answer: A
Explanation: The correct syntax to throw an exception manually is throw new Exception("Error message");.
Question 33
What keyword is used to prevent a class from being subclassed?
- A. final
- B. static
- C. private
- D. protected
Answer: A
Explanation: The final keyword prevents a class from being subclassed.
Question 34
How do you retrieve the size of an ArrayList in Java?
- A. arrayList.size();
- B. arrayList.length;
- C. arrayList.getSize();
- D. arrayList.count();
Answer: A
Explanation: The size() method retrieves the number of elements in an ArrayList.
Question 35
What will happen if you try to modify a string in Java?
- A. The original string will change
- B. A new string will be created
- C. It will throw an error
- D. Nothing will happen
Answer: B
Explanation: Strings in Java are immutable; modifying a string will create a new string instead of changing the original.
Question 36
Which of the following is a valid declaration of an enum in Java?
- A. enum Colors { RED, GREEN, BLUE }
- B. enum Colors[] { RED, GREEN, BLUE }
- C. Colors { RED, GREEN, BLUE }
- D. public Colors { RED, GREEN, BLUE }
Answer: A
Explanation: The correct way to declare an enum is enum Colors { RED, GREEN, BLUE }.
Question 37
How can you handle multiple exceptions in a single catch block?
- A. catch (IOException | SQLException e) { … }
- B. catch (IOException e) { … } catch (SQLException e) { … }
- C. catch (IOException, SQLException e) { … }
- D. Both A and B
Answer: D
Explanation: Both catch (IOException | SQLException e) { ... } and separate catch blocks handle multiple exceptions.
Question 38
What will be the output of System.out.println(10 + 5 + ” is the sum.”);?
- A. 15 is the sum.
- B. 10 + 5 is the sum.
- C. 105 is the sum.
- D. Error
Answer: A
Explanation: The expression evaluates to 15, resulting in "15 is the sum." due to string concatenation.
Question 39
Which method is used to convert a string to uppercase?
- A. str.toUpperCase()
- B. str.upper()
- C. str.toUpper()
- D. str.makeUpperCase()
Answer: A
Explanation: The toUpperCase() method converts a string to uppercase.
Question 40
How can you remove an element from an ArrayList?
- A. arrayList.remove(index);
- B. arrayList.delete(index);
- C. arrayList.erase(index);
- D. arrayList.clear(index);
Answer: A
Explanation: The remove(index) method is used to remove an element from an ArrayList.
