The Command Design Pattern is a behavioural design pattern that turns a request into a stand-alone object containing all the information about the request. This pattern allows you to parameterize objects with operations, delay the execution of an operation, or queue a request for execution. Simple Example: Imagine you have a remote control that can turn on and off a light. The Command Pattern can be used to encapsulate these operations into objects....
Imagine you’re sending a package. It goes through various checkpoints: sorting, security, customs, etc. Each checkpoint decides whether to handle the package or pass it on to the next. This is similar to the Chain of Responsibility pattern. Key Idea: A request is passed along a chain of objects. Each object decides whether to handle or pass the request to the next. This creates a loose coupling between the sender and receiver....
The Interpreter Pattern is a design pattern used to define a grammatical representation of a language and provide an interpreter to deal with this grammar. It is useful for interpreting expressions in a language. Simple Explanation: Grammar: Define the rules of the language. Expressions: Create classes for each rule in the grammar. Context: Store information that might be needed during interpretation. Interpreter: Evaluate the expressions based on the rules. Example: Imagine a simple language for arithmetic expressions with numbers, addition, and multiplication....
The Iterator pattern provides a way to access the elements of a collection without exposing its internal structure. It promotes loose coupling between the collection and the code that uses it. Key Components: Iterator: Defines the interface for accessing and traversing elements in a collection. Concrete Iterator: Implements the Iterator interface and keeps track of the current position in the traversal. Aggregate: Defines an interface for creating an Iterator object. Concrete Aggregate: Implements the Aggregate interface and creates a Concrete Iterator....
Understanding the Problem Imagine you’re building a text editor. Users often make mistakes or want to revert changes. How can you allow them to undo their actions without exposing the internal state of the document? The Memento Solution The Memento pattern provides a solution by capturing and storing the internal state of an object without violating encapsulation. Key Players: Originator: The object whose state needs to be saved (e.g., the text editor)....
The Mediator pattern promotes loose coupling between objects by introducing a mediator that handles communication between them. This reduces dependencies and makes the system more flexible and maintainable. A Simple Chat Room Example Let’s consider a basic chat room application with multiple users. Instead of users communicating directly with each other, they’ll send messages to a chat room (the mediator), which then broadcasts the message to all users. 1. Define the Mediator Interface: interface ChatRoom { void registerUser(User user); void send(String msg, User user); } 2....
Introduction In modern applications, messaging systems play a crucial role in enabling communication between different components and services. Apache ActiveMQ Artemis is a popular open-source messaging broker that supports multiple protocols, including AMQP. In this blog post, we will explore how to connect a Spring Boot 3 application to an Apache ActiveMQ Artemis broker using the AMQP protocol and configure it to support transactions. Prerequisites Before we begin, ensure you have the following:...
Importing a CA Certificate in RHEL/CentOS Copy the Certificate: sudo cp your-ca-certificate.crt /etc/pki/ca-trust/source/anchors/ Update the CA Trust: sudo update-ca-trust extract Importing a CA Certificate in Ubuntu/Debian Copy the Certificate: sudo cp your-ca-certificate.crt /usr/local/share/ca-certificates/ Update the CA Trust: sudo update-ca-certificates Importing a CA Certificate in Fedora Copy the Certificate: sudo cp your-ca-certificate.crt /etc/pki/ca-trust/source/anchors/ Update the CA Trust: sudo update-ca-trust Importing a CA Certificate in SUSE/OpenSUSE Copy the Certificate: sudo cp your-ca-certificate.crt /etc/pki/trust/anchors/ Update the CA Trust:...
1. Introduction to Stack in Java Definition: A stack is a linear data structure that follows the Last In First Out (LIFO) principle. Operations: Push: Adds an element to the top of the stack. Pop: Removes and returns the top element of the stack. Peek: Returns the top element without removing it. isEmpty: Checks if the stack is empty. size: Returns the number of elements in the stack. 2. Implementing a Stack in Java Using java....
Linked lists are a fundamental data structure that every software developer should understand. They form the basis for many other data structures and algorithms. In this blog post, we’ll explore how to implement a linked list in Java and cover some of the trickiest parts that you might encounter during interviews. What is a Linked List? A linked list is a linear data structure where each element, called a node, contains a reference (or link) to the next node in the sequence....