Interview Questions and Answers

HashMap and HashTable are both data structures in Java used to store key-value pairs, but HashMap is not synchronized and allows null keys/values, while HashTable is synchronized and does not allow null keys/values.

• HashMap is not synchronized, while HashTable is synchronized

• HashMap allows null keys and values, while HashTable does not

• HashMap is faster than HashTable

• HashMap is part of Java Collections framework, while HashTable is a legacy class

OOPs stands for Object-Oriented Programming. It is a programming paradigm based on the concept of objects.

• Advantages of OOPs include code reusability, modularity, flexibility, and easier maintenance.

• Encapsulation allows data hiding and protection, reducing complexity and increasing security.

• Inheritance enables code reuse and promotes the creation of hierarchical relationships between classes.

• Polymorphism allows objects to be treated as instances of their parent class, providi...read more

String buffer is a data structure that stores and manipulates a sequence of characters.

• String buffer is mutable, meaning it can be modified after creation.

• It is often used for efficient string manipulation, such as concatenation or appending.

• Examples include StringBuffer class in Java and StringBuilder class in C#.

An exception is an event that disrupts the normal flow of a program's execution.

• Exceptions are used to handle errors and other exceptional events in software.

• They can be caught and handled using try-catch blocks.

• Examples of exceptions include NullPointerException, ArrayIndexOutOfBoundsException, and IOException.

PHP is a server-side scripting language used for web development.

• PHP stands for Hypertext Preprocessor.

• It is open source and widely used for creating dynamic web pages.

• Advantages include easy integration with HTML, support for various databases, and compatibility with different operating systems.

• PHP code can be embedded within HTML code, making it easy to work with web content.

• Popular websites like Facebook and WordPress are built using PHP.