Visionet Systems Interview Questions and Answers

Find the maximum element in an array after performing a series of increment operations on specified ranges.

• Initialize an array of size N with all zeros

• Iterate through the operations and increment elements within specified ranges

• Return the maximum element in the array after all operations

Use two threads to print even and odd numbers in increasing order.

• Create two threads, one for printing even numbers and one for printing odd numbers.

• Use a shared variable to keep track of the current number to be printed.

• Synchronize access to the shared variable to ensure correct ordering of numbers.

• Use a loop in each thread to print the next number and update the shared variable.

HashMap in Java is a data structure that stores key-value pairs and uses hashing to efficiently retrieve values based on keys.

• HashMap internally uses an array of linked lists to store key-value pairs.

• When a key-value pair is added, the key is hashed to find the index in the array where it will be stored.

• If multiple keys hash to the same index, a linked list is used to handle collisions.

• Retrieving a value involves hashing the key to find the index and then traversing the linke...read more

Overriding equals and hashCode methods in Java is important for proper object comparison and hashing.

• Equals method is used to compare two objects for equality, while hashCode method is used to generate a unique integer value for an object.

• By overriding equals and hashCode methods, we can ensure that objects are compared based on their actual content rather than memory address.

• This is crucial for collections like HashMap and HashSet, where proper implementation of equals and h...read more

Synchronized Collection is thread-safe but may have performance issues, while Concurrent Collection is optimized for concurrent access.

• Synchronized Collection uses synchronized keyword to achieve thread-safety, while Concurrent Collection uses non-blocking algorithms like CAS (Compare and Swap).

• Synchronized Collection locks the entire collection during modification, leading to potential performance bottlenecks, while Concurrent Collection allows multiple threads to access and...read more

CopyOnWriteArrayList creates a new copy of the underlying array whenever an element is added, modified, or removed.

• CopyOnWriteArrayList is thread-safe and suitable for scenarios where reads are more frequent than writes.

• Adding, modifying, or removing elements in CopyOnWriteArrayList creates a new copy of the underlying array, ensuring thread safety.

• Iterators on CopyOnWriteArrayList operate on the original array and do not throw ConcurrentModificationException.