Fill2Earn Interview Questions and Answers

A circular linked list is a linked list where the last node points back to the first node, forming a loop.

• Create a Node class with data and next pointer

• Initialize the head and tail pointers to null

• When adding a node, if the list is empty, set head and tail to the new node

• If the list is not empty, set the next pointer of the tail to the new node and update the tail

• To traverse the circular linked list, start from the head and keep moving to the next node until you reach the hea...read more

To create a singleton class in a multi-threaded environment, we can use double-checked locking or synchronized block.

• Use double-checked locking to minimize the use of synchronization and improve performance.

• In double-checked locking, check if the instance is null, then synchronize the block and create the instance.

• Use volatile keyword to ensure visibility of the instance across threads.

• Alternatively, use synchronized block to create a thread-safe singleton class.

• In synchroniz...read more

The wait method in the Object class is used for inter-thread communication and synchronization.

• wait() is used to make a thread wait until another thread notifies it.

• It is used in multi-threaded applications to coordinate the execution of threads.

• wait() releases the lock held by the current thread, allowing other threads to acquire it.

• It is typically used in conjunction with notify() and notifyAll() methods.

• Example: wait() can be used to implement the producer-consumer pattern...read more

An immutable class in Java is a class whose state cannot be modified after it is created.

• Declare the class as final to prevent inheritance

• Declare all fields as private and final

• Do not provide any setter methods

• Ensure that any mutable objects within the class are not accessible or modifiable

• Provide only getter methods to access the fields

• If a field is mutable, return a copy of it instead of the original object

RDBMS is a relational database management system that uses structured data, while NoSQL is a non-relational database that uses unstructured data.

• RDBMS stores data in tables with predefined schemas, while NoSQL stores data in various formats like key-value, document, columnar, or graph.

• RDBMS supports ACID (Atomicity, Consistency, Isolation, Durability) properties, while NoSQL sacrifices some of these properties for scalability and performance.

• RDBMS is suitable for structured d...read more

No, generics are not limited to collections.

• Generics can be used with any type of class or interface, not just collections.

• They provide type safety and allow for code reusability.

• For example, generics can be used with classes like ArrayList, LinkedList, HashMap, etc.

• They can also be used with interfaces like Comparable, Iterator, etc.

HashMap is an unordered collection while LinkedHashMap maintains insertion order.

• HashMap uses hash table to store key-value pairs.

• LinkedHashMap uses doubly-linked list to maintain the insertion order.

• HashMap provides faster access and retrieval time complexity.

• LinkedHashMap provides predictable iteration order based on insertion order.

• Example: HashMap - {1=A, 2=B, 3=C}, LinkedHashMap - {1=A, 2=B, 3=C}