What will be the output of the code?
❌ A. 10
✅ B. 20
❌ C. 30
❌ D. Compilation error
❌ E. Runtime error
❌ F. None of the above
Explanation:
The code defines a class MyClass with a private instance variable myVar, a constructor that initializes myVar, and getter and setter methods for myVar.
In the Main class, an object obj1 of MyClass is created with the value 10 passed as an argument to the constructor. Then, obj2 is assigned a reference to the same object as obj1. Next, the setMyVar() method is called on obj2 with a value of 20. Finally, the value of myVar in obj1 is printed.
Since obj1 and obj2 refer to the same object, calling setMyVar() on obj2 also changes the value of myVar in obj1. Therefore, the output will be 20.
Therefore, the correct answer is option 20.
❌ A. 10
✅ B. 20
❌ C. 30
❌ D. Compilation error
❌ E. Runtime error
❌ F. None of the above
Explanation:
The code defines a class MyClass with a private instance variable myVar, a constructor that initializes myVar, and getter and setter methods for myVar.
In the Main class, an object obj1 of MyClass is created with the value 10 passed as an argument to the constructor. Then, obj2 is assigned a reference to the same object as obj1. Next, the setMyVar() method is called on obj2 with a value of 20. Finally, the value of myVar in obj1 is printed.
Since obj1 and obj2 refer to the same object, calling setMyVar() on obj2 also changes the value of myVar in obj1. Therefore, the output will be 20.
Therefore, the correct answer is option 20.
What will be the output of the code?
✅ A. Vehicle is moving at a speed of 100 km/h. This car is red
❌ B. Car is moving at a speed of 100 km/h. This car is red
❌ C. This car is red
❌ D. Compilation error
❌ E. Runtime error
❌ F. None of the above
Explanation:
The code defines two classes Vehicle and Car. Vehicle is a superclass that has a protected instance variable speed and a method move() that prints the current speed of the vehicle. Car is a subclass of Vehicle that adds a private instance variable color and a method display() that prints the color of the car.
The Main class creates a Car object myCar with a speed of 100 and a color of "red". The move() method is called on myCar, which is inherited from Vehicle, and it prints "Vehicle is moving at a speed of 100 km/h". The display() method is then called on myCar and it prints "This car is red".
Therefore, the correct answer is option A Vehicle is moving at a speed of 100 km/h and This car is red. The output first shows the message printed by the move() method of the Vehicle superclass, and then the message printed by the display() method of the Car subclass.
✅ A. Vehicle is moving at a speed of 100 km/h. This car is red
❌ B. Car is moving at a speed of 100 km/h. This car is red
❌ C. This car is red
❌ D. Compilation error
❌ E. Runtime error
❌ F. None of the above
Explanation:
The code defines two classes Vehicle and Car. Vehicle is a superclass that has a protected instance variable speed and a method move() that prints the current speed of the vehicle. Car is a subclass of Vehicle that adds a private instance variable color and a method display() that prints the color of the car.
The Main class creates a Car object myCar with a speed of 100 and a color of "red". The move() method is called on myCar, which is inherited from Vehicle, and it prints "Vehicle is moving at a speed of 100 km/h". The display() method is then called on myCar and it prints "This car is red".
Therefore, the correct answer is option A Vehicle is moving at a speed of 100 km/h and This car is red. The output first shows the message printed by the move() method of the Vehicle superclass, and then the message printed by the display() method of the Car subclass.
What will be the output of the code?
❌ A. The sum of even numbers is 22
❌ B. The sum of even numbers is 24
✅ C. The sum of even numbers is 30
❌ D. The sum of even numbers is 54
❌ E. The code will not compile
❌ F. None of the above
Explanation:
The code creates a list of integers and uses the Stream API to filter the even numbers, convert them to primitive int values, and sum them up. The filter() method takes a lambda expression that tests whether a number is even by checking if it is divisible by 2. The mapToInt() method converts the Integer objects to int primitive values, which are required by the sum() method.
The resulting sum of the even numbers is 2 + 4 + 6 + 8 + 10 = 30.
Therefore, the correct answer is option C) The sum of even numbers is 30. The program will output "The sum of even numbers is 30" to the console.
❌ A. The sum of even numbers is 22
❌ B. The sum of even numbers is 24
✅ C. The sum of even numbers is 30
❌ D. The sum of even numbers is 54
❌ E. The code will not compile
❌ F. None of the above
Explanation:
The code creates a list of integers and uses the Stream API to filter the even numbers, convert them to primitive int values, and sum them up. The filter() method takes a lambda expression that tests whether a number is even by checking if it is divisible by 2. The mapToInt() method converts the Integer objects to int primitive values, which are required by the sum() method.
The resulting sum of the even numbers is 2 + 4 + 6 + 8 + 10 = 30.
Therefore, the correct answer is option C) The sum of even numbers is 30. The program will output "The sum of even numbers is 30" to the console.
Which of the statements about this program is correct?
❌ A. It compiles and prints 14
❌ B. It compiles and prints 15
❌ C. The code will not compile because of line 4
❌ D. The code will not compile because of line 5
✅ E. The code will not compile because of line 6
❌ F. None of the above
Explanation:
The inherited interface method getNumOfGills(int) is implicitly public; therefore, it must be declared public in any concrete class that implements the interface. Since the method uses the default (package-private) modifier in the ClownFish class, line 6 does not compile, making option E the correct answer. If the method declaration was corrected to include public on line 6, then the program would compile and print 15 at runtime, and option B would be the correct answer.
❌ A. It compiles and prints 14
❌ B. It compiles and prints 15
❌ C. The code will not compile because of line 4
❌ D. The code will not compile because of line 5
✅ E. The code will not compile because of line 6
❌ F. None of the above
Explanation:
The inherited interface method getNumOfGills(int) is implicitly public; therefore, it must be declared public in any concrete class that implements the interface. Since the method uses the default (package-private) modifier in the ClownFish class, line 6 does not compile, making option E the correct answer. If the method declaration was corrected to include public on line 6, then the program would compile and print 15 at runtime, and option B would be the correct answer.
What distinct numbers are printed when the method is executed?
❌ A. 6
✅ B. 3
❌ C. 4
❌ D. 5
✅ E. 10
❌ F. 9
❌ G. The code does not compile
❌ H. None of the above
Explanation:
The code compiles without issue and prints three distinct numbers at runtime, so options G and H are incorrect. The first loop executes a total of five times, with the loop ending when participants has a value of 10. For this reason, option E is correct. In the second loop, animals already starts out not less than or equal to 1, but since it is a do/while loop, it executes at least once. In this manner, animals takes on a value of 3 and the loop terminates, making option B correct. Finally, the last loop executes a total of two times, with performers starting with -1, going to 1 at the end of the first loop, and then ending with a value of 3 after the second loop, which breaks the loop. This makes option B a correct answer twice over.
❌ A. 6
✅ B. 3
❌ C. 4
❌ D. 5
✅ E. 10
❌ F. 9
❌ G. The code does not compile
❌ H. None of the above
Explanation:
The code compiles without issue and prints three distinct numbers at runtime, so options G and H are incorrect. The first loop executes a total of five times, with the loop ending when participants has a value of 10. For this reason, option E is correct. In the second loop, animals already starts out not less than or equal to 1, but since it is a do/while loop, it executes at least once. In this manner, animals takes on a value of 3 and the loop terminates, making option B correct. Finally, the last loop executes a total of two times, with performers starting with -1, going to 1 at the end of the first loop, and then ending with a value of 3 after the second loop, which breaks the loop. This makes option B a correct answer twice over.
What will be the output of the code?
❌ A. Counter value: 20000
✅ B. Counter value: Less than 20000
❌ C. Counter value: More than 20000
❌ D. Compilation error
❌ E. Runtime error
❌ F. None of the above
Explanation:
This code snippet demonstrates a scenario where two threads (t1 and t2) increment a shared static variable counter. Each thread iterates 10000 times and increments the counter.
Due to the concurrent nature of multithreading, the increment operation (counter++) is not atomic. It consists of reading the current value of counter, adding 1 to it, and then writing the new value back. This introduces a race condition.
It's possible that while one thread is performing the read-modify-write operation, the other thread may perform a similar operation concurrently, causing the updates to overlap and potentially leading to lost updates.
The correct answer is option B) Counter value: Less than 20000. The exact output value can vary due to the race condition. The threads might interfere with each other's updates, causing some increments to be lost. Therefore, the output value will likely be less than 20000.
In a multithreaded scenario like this, proper synchronization mechanisms (e.g., synchronized keyword or AtomicInteger) should be used to ensure the correct behavior of shared variables.
❌ A. Counter value: 20000
✅ B. Counter value: Less than 20000
❌ C. Counter value: More than 20000
❌ D. Compilation error
❌ E. Runtime error
❌ F. None of the above
Explanation:
This code snippet demonstrates a scenario where two threads (t1 and t2) increment a shared static variable counter. Each thread iterates 10000 times and increments the counter.
Due to the concurrent nature of multithreading, the increment operation (counter++) is not atomic. It consists of reading the current value of counter, adding 1 to it, and then writing the new value back. This introduces a race condition.
It's possible that while one thread is performing the read-modify-write operation, the other thread may perform a similar operation concurrently, causing the updates to overlap and potentially leading to lost updates.
The correct answer is option B) Counter value: Less than 20000. The exact output value can vary due to the race condition. The threads might interfere with each other's updates, causing some increments to be lost. Therefore, the output value will likely be less than 20000.
In a multithreaded scenario like this, proper synchronization mechanisms (e.g., synchronized keyword or AtomicInteger) should be used to ensure the correct behavior of shared variables.
What will be the output of the code?
❌ A. 1
✅ B. 2
❌ C. 3
❌ D. Compilation error
❌ E. Runtime error
❌ F. None of the above
Explanation:
In this code snippet, the processMap method uses the computeIfAbsent method of the Map interface. If the specified key is not already associated with a value (or is mapped to null), this method associates it with the result of the given function.
In this case, the key "Two" is already present in the map with the value 2. Therefore, the computeIfAbsent method does not execute the provided function (k -> k.length()), and it returns the current value associated with the key "Two," which is 2.
Option A might be tempting, but it is incorrect because the computeIfAbsent method doesn't execute the function when the key is already present in the map. Option B is the correct answer, representing the value associated with the existing key "Two."
Options C and D are incorrect as there is no compilation error or runtime exception in this code. The behavior is as expected with the use of the computeIfAbsent method.
❌ A. 1
✅ B. 2
❌ C. 3
❌ D. Compilation error
❌ E. Runtime error
❌ F. None of the above
Explanation:
In this code snippet, the processMap method uses the computeIfAbsent method of the Map interface. If the specified key is not already associated with a value (or is mapped to null), this method associates it with the result of the given function.
In this case, the key "Two" is already present in the map with the value 2. Therefore, the computeIfAbsent method does not execute the provided function (k -> k.length()), and it returns the current value associated with the key "Two," which is 2.
Option A might be tempting, but it is incorrect because the computeIfAbsent method doesn't execute the function when the key is already present in the map. Option B is the correct answer, representing the value associated with the existing key "Two."
Options C and D are incorrect as there is no compilation error or runtime exception in this code. The behavior is as expected with the use of the computeIfAbsent method.