Category: Java

Posted on: January 18, 2025 Posted by: rahulgite Comments: 0

Java Exception Handling

Exception handling is a mechanism in Java to handle runtime errors, ensuring normal application flow. 1. Exception Hierarchy in Java The Throwable class is the root of Java’s exception hierarchy. 2. Exception vs. Error Feature Exception Error Definition Recoverable conditions in the program. Critical issues not meant to be handled. Hierarchy Subclass of Throwable. Subclass of Throwable. Examples IOException, SQLException. StackOverflowError, OutOfMemoryError. Handling Can be handled with try-catch. Should not…

Posted on: January 18, 2025 Posted by: rahulgite Comments: 0

Serialization and Deserialization in Java

Serialization and deserialization are processes used to save and retrieve the state of Java objects. They are crucial for transmitting objects over a network, saving objects to files, or caching. 1. What is Serialization? 2. What is Deserialization? 3. Key Concepts of Serialization 4. Serialization Example Saving an Object to a File 5. Deserialization Example Reading an Object from a File 6. Important Notes 7. Applications of Serialization 8. Limitations…

Posted on: January 18, 2025 Posted by: rahulgite Comments: 0

JDBC in Java

Java Database Connectivity (JDBC) is an API that allows Java applications to interact with databases. It provides methods to query and update data in a database using SQL. 1. JDBC Driver 2. Steps in JDBC Example: JDBC Steps 3. Components of JDBC API 4. JDBC Connection Interface 5. Difference Between executeQuery(), executeUpdate(), and execute() Method Purpose Return Value Use Case executeQuery() Executes a SELECT query. Returns a ResultSet. Fetching data…

Posted on: January 18, 2025 Posted by: rahulgite Comments: 0

What are Servlets in Java?

Servlets are Java programs that run on a server, handling client requests and generating dynamic web content. They are a key part of Java’s server-side programming model. 1. What is a Servlet? Example: Basic Servlet 2. Lifecycle of a Servlet The servlet lifecycle consists of the following stages: Example: Lifecycle Methods 3. Sessions in Servlets Example: Using HttpSession 4. ServletConfig vs ServletContext Feature ServletConfig ServletContext Scope Specific to a single…

Posted on: January 18, 2025 Posted by: rahulgite Comments: 0

What is Multiple Inheritance? Is Multiple Inheritance Supported in Java?

Multiple Inheritance in Java What is Multiple Inheritance? Is Multiple Inheritance Supported in Java? Java does not support multiple inheritance with classes to avoid ambiguity caused by the Diamond Problem. However, it supports multiple inheritance with interfaces. 1. Multiple Inheritance with Classes Why Not Supported? The Diamond Problem occurs when a class inherits from two classes that have a method with the same signature. Java avoids this problem by disallowing…

Posted on: January 18, 2025 Posted by: rahulgite Comments: 0

Encapsulation, Inheritance, and Polymorphism in Java

These three concepts are fundamental pillars of Object-Oriented Programming (OOP) in Java. They enable code reusability, scalability, and maintainability. 1. Encapsulation Example: Encapsulation 2. Inheritance Example: Inheritance 3. Polymorphism Example: Compile-Time Polymorphism (Method Overloading) Example: Runtime Polymorphism (Method Overriding) Key Differences Between Compile-Time and Runtime Polymorphism Feature Compile-Time Polymorphism Runtime Polymorphism Definition Achieved through method overloading. Achieved through method overriding. Binding Resolved during compile time. Resolved during runtime. Flexibility Less…

Posted on: January 18, 2025 Posted by: rahulgite Comments: 0

Abstract Class vs Interface in Java

Java provides two mechanisms to achieve abstraction: abstract classes and interfaces. Both have their unique features and use cases. 1. Abstract Class Example: Abstract Class 2. Interface Example: Interface Key Differences Between Abstract Class and Interface Feature Abstract Class Interface Definition A class with abstract and concrete methods. A blueprint containing abstract methods and constants. Constructors Can have constructors. Cannot have constructors. Instance Variables Can have instance variables. Cannot have…

Posted on: January 18, 2025 Posted by: rahulgite Comments: 0

What is difference between equals() vs == in Java

equals() vs == in Java Java provides two mechanisms for comparing objects and primitive types: the equals() method and the == operator. Both have distinct purposes and behaviors. 1. == Operator Example: Using == with Primitives Example: Using == with Objects 2. equals() Method Example: Using equals() with Objects 3. Custom Implementation of equals() and hashCode() When creating custom classes, overriding both equals() and hashCode() is essential to maintain the…

Posted on: January 18, 2025 Posted by: rahulgite Comments: 0

Can We Overload and Override Static Methods in Java?

Overloading Static Methods Overloading occurs when two or more methods in the same class have the same name but different parameter lists. Since static methods are resolved at compile time, overloading works as expected. Example: Overloading Static Methods Output: Key Points for Overloading: Overriding Static Methods Overriding refers to defining a method in a subclass that has the same name, return type, and parameters as a method in its superclass.…

Posted on: January 18, 2025 Posted by: rahulgite Comments: 0

What is the Java Collections?

The Java Collections Framework provides a set of classes and interfaces for managing groups of objects. It simplifies data handling by offering various data structures, algorithms, and utilities. Hierarchy of Collections Framework Overview of Collections Collection Interface Description List Ordered collection that allows duplicate elements. Set Unordered collection that does not allow duplicate elements. Queue Ordered collection that supports element processing in FIFO order. Map Collection of key-value pairs, where…