FirstRand Services Backend Java Developer Interview Questions and Answers

HashMap 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 determine the index in the array where the pair will be stored.

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

• Retrieving a value involves ha...read more

A singleton class is a class that can only have one instance created and provides a global point of access to that instance.

• Ensure the class has a private constructor to prevent external instantiation.

• Provide a static method to access the single instance of the class.

• Use lazy initialization to create the instance only when needed.

• Consider thread safety if the singleton will be accessed by multiple threads.