Cognizant Associate Interview Questions, Process, and Tips

String is immutable because it cannot be changed once created.

• Immutable objects are safer to use in multi-threaded environments

• String pool in Java is possible because of immutability

• StringBuffer and StringBuilder classes are used for mutable strings

HashMap is a key-value pair collection while HashSet is a set of unique elements.

• HashMap allows duplicate values but not duplicate keys

• HashSet does not allow duplicate elements

• HashMap uses key to retrieve values while HashSet uses contains() method to check if an element exists

• Example: HashMap - {1=apple, 2=banana, 3=apple}, HashSet - {apple, banana}

• HashMap implements Map interface while HashSet implements Set interfac

Functional Interface has only one abstract method while Normal Interface can have multiple abstract methods.

• Functional Interface is used for lambda expressions and method references.

• Normal Interface can have default and static methods along with abstract methods.

• Example of Functional Interface: java.util.function.Predicate

• Example of Normal Interface: java.util.List

StringBuffer is synchronized while StringBuilder is not.

• StringBuffer is thread-safe while StringBuilder is not.

• StringBuffer is slower than StringBuilder due to synchronization.

• StringBuilder is preferred for single-threaded environments.

• Both classes are used for manipulating strings.

• Example: StringBuffer sb = new StringBuffer("Hello");

• Example: StringBuilder sb = new StringBuilder("Hello");

Design patterns are reusable solutions to common software design problems.

• Design patterns provide a common language for developers to communicate about solutions to common problems.

• They can improve the quality, maintainability, and scalability of software.

• Examples of design patterns include the Singleton pattern, Factory pattern, and Observer pattern.

Creating threads in programming and the different ways to do so.

• Threads can be created by extending the Thread class and overriding the run() method.

• Threads can also be created by implementing the Runnable interface and passing it to a Thread object.

• Java 8 introduced the concept of creating threads using lambda expressions.

• Thread pools can be used to manage a group of threads.

• Examples: Thread t1 = new Thread(); t1.star...read more