Mastering Design Patterns - Become a Professional Developer

Mastering design patterns teaches elegant, language independent solutions to repeating problems, with patterns like singleton that make classes reusable and well structured across creational, structural, and behavioral categories.

Master Java syntax by learning case sensitivity, naming conventions for classes and methods, and file-name rules. Create a Hello World program using the main method to print a message.

Explore object oriented programming concepts, compare procedural programming, and learn how a class is a template for objects with attributes and methods, illustrated by a car example.

Create and initialize Java objects with constructors to set weight and color. Overload constructors with different parameters and use this to assign values during object creation.

Discover how Java inheritance lets a car extend vehicle, reuse methods like horn from the parent, with Mercedes as an example and notes on final to prevent inheritance.

Learn how polymorphism uses inheritance to let an animal class become a cat or a dog, override the animal sound, and enable up casting for code reuse.

Explore abstraction by hiding details and exposing essential information through abstract classes or interfaces, enforcing concrete implementations of animal sound while leveraging inheritance and polymorphism.

Use interfaces to achieve abstraction in Java by declaring methods without bodies. See how dog and cat implement the interface using the implements keyword and compare with abstract classes.

Explore the UML class diagram language to visualize object-oriented structures by modeling classes, attributes, operations, and relationships such as inheritance, composition, aggregation, and dependency.

Explore structural design patterns that assemble objects into flexible, efficient structures, focusing on inheritance and composition across adapter, proxy, bridge, composite, decorator, facade, and lightweight patterns, with in-depth examples.

Explore adapter design pattern, structural pattern that converts a class interface to match client expectations by wrapping a service with an adapter, and four parts: client, client interface, adapter, surface.

Apply the adapter pattern to let incompatible vehicle interfaces collaborate, enabling speed display in mph or km/h without changing existing cars, as shown with Maserati, Porsche, and Bugatti.

In this lecture, we implement a vehicle hierarchy with Maserati, Porsche, and Bugatti, test it via a client, and prepare an adapter-based solution to display speed in mph and km/h.

Explore the adapter design pattern in UML by implementing an interface adapter to convert vehicle speeds between miles per hour and kilometers per hour without modifying existing vehicle classes.

Apply the adapter design pattern to display car speeds in mph and km/h without modifying the original vehicle classes, using a vehicle adapter and an adapter service.

Bridge incompatible interfaces with the adapter design pattern, letting a client use a legacy service through a common shape interface for drawing and managing shapes such as triangle and circle.

Demonstrate the adapter pattern by bridging a shape interface with draw, resize, description, and is height to an interface with area and perimeter, applied to rectangle, circle, triangle, and rhombus.

Learn how to adapt triangle and rhombus to a common shape interface with a geometric shape object adapter, enabling draw, resize, and description methods to behave like rectangle and circle.

Explore the adapter design pattern by implementing triangle and rhombus adapters that wrap shapes to support draw, resize, description, and height in Java.

Explore the proxy pattern, a pattern that provides a substitute for an original object to control access, enable lazy initialization, and cache results via a proxy with the same interface.

Explore how the proxy pattern mirrors real life, using a credit card as a proxy for cash and a bank account to enable secure, electronic payments.

See how to avoid memory leak by loading a large image from disk only once and reusing it for multiple displays.

Implement the proxy design pattern to optimize image handling by loading from disk only once and reusing a single image instance, reducing memory usage and preventing repeated loads.

Demonstrate a virtual proxy in the proxy design pattern by creating a proxy image that implements the same interface as the real image and loads from disk on demand.

Explore the proxy design pattern to restrict internet access by rank, using an internet access interface and a real internet access class so only rank five and above gain access.

Apply the proxy design pattern to control internet access by employee rank, granting access only for rank five and above and delegating to a real internet access object when allowed.

Explore the bridge design pattern, separating abstraction from implementation across five parts: abstraction, implementation, concrete implementations, refined abstractions, and client, where the UI delegates low-level work to platform-specific code.

Examine why adding new shapes and colors causes exponential growth in a shape hierarchy and how the bridge design pattern decouples shapes from colors in a Java implementation.

This lecture demonstrates the bridge pattern, separating shape abstraction from color implementation with composition, enabling new colors or shapes without changing existing classes, reducing boilerplate.

Explore why a deep vehicle hierarchy causes code duplication and maintenance challenges. See how the bridge design pattern decouples production steps—produce, assemble, painting, and testing—to improve reusability and testability.

Use the bridge design pattern to decouple vehicle abstractions from their produce, assemble, paint, and test workshops, enabling adding trucks or lubrication workshops without touching bike, car, or bus code.

Explore the composite design pattern, a structural approach that treats leaves and composites uniformly via a common component interface, with containers delegating work and leaves performing tasks.

Explore the composite design pattern by building a drawing structure where squares, circles, lines, and triangles are treated uniformly, so coloring the drawing applies to all shapes.

Master the composite design pattern by building leaf shapes like triangle and circle and a drawing composite that applies a single color fill to all leaves.

Explore the composite design pattern by modeling a file system where folders are files that contain other files, and links point to specific files in a tree-like hierarchy.

Implement a composite design pattern to model a file system with leaf files and directories treated as files. Build a file class, a directory class, and file attributes classes.

Implement a file system hierarchy using the composite pattern in Java, creating file and directory classes with a tree set of file attributes and a recursive display to show attributes.

Explore implementing the composite design pattern by building a file and directory hierarchy, with file attributes and a comparable interface, then display and test the hierarchical tree.

Explore the decorator design pattern, which attaches new behaviors to objects by wrapping them with decorators, using a base decorator, concrete decorators, and a component interface for layered extensions.

Model a pizza store with an abstract pizza class and types like margherita, veggie, and pepperoni, then show how toppings explode subclasses and violate open-closed principle, leading to decorator pattern.

Apply the decorator design pattern to extend a pizza object with toppings like cheese and tomato, demonstrating dynamic composition and a flexible alternative to subclassing.

Implement a Java pizza system with the decorator pattern, using an abstract pizza, concrete pizzas, and toppings like cheese, tomato, and barbecue to compute runtime cost and description.

Apply the decorator pattern to a car object to add luxury and sports features, avoiding difficult inheritance and composition hierarchies and enabling flexible feature combination.

Explore the decorator design pattern to compose a basic car with luxury and sport features, preventing the need for many classes and enabling runtime feature additions.

Explore the facade design pattern, a structural pattern that offers a simple interface to complex subsystems and hides their details behind a friendly front, directing tasks like payment and delivery.

Apply the facade design pattern to simplify access to multiple restaurant menus through a hotel keeper, hiding complex restaurant details behind a single interface.

Explore how the facade pattern hides internal complexity by exposing a single interface through a hotel keeper, managing veg, non-veg, and both menus.

Explore creational design patterns: factory, abstract factory, builder, prototype, and singleton, which enable flexible object creation, controlled instantiation, and object copying.