Java Trainee Interview Questions and Answers for Freshers

Collection is an interface that represents a group of objects while Collections is a utility class that provides methods to operate on collections.

• Collection is an interface while Collections is a class

• Collection is used to represent a group of objects while Collections provides utility methods to operate on collections

• Example of Collection: List, Set, Queue

• Example of Collections: sort(), reverse(), shuffle()

To find the second largest number in an array of integers.

• Sort the array in descending order and return the second element.

• Iterate through the array and keep track of the two largest numbers.

• Use a priority queue to find the second largest element.

Multithreading is a programming concept that allows concurrent execution of two or more threads for improved performance.

• Multithreading enables parallel execution, improving application responsiveness.

• In Java, threads can be created by extending the Thread class or implementing the Runnable interface.

• Example: Using Runnable interface to create a thread for a task.

• Multithreading is useful in applications like web servers, where multiple requests are handled simultaneously.

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The Collection Framework in Java provides a set of classes and interfaces for storing and manipulating groups of objects.

• Consists of interfaces like List, Set, and Map for different data structures.

• ArrayList is a resizable array implementation of the List interface.

• HashSet implements the Set interface and stores unique elements.

• HashMap stores key-value pairs and allows fast retrieval based on keys.