Easy Guide to Java Design Patterns
Think of design patterns as ready-made solutions for common programming puzzles that seasoned coders encounter.
Picture a team known as the “Gang of Four,” starring coding wizards Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides. They penned a book that unveiled 23 clever patterns. These patterns are like tools to tackle recurring issues when building software.
Let’s break them down into three groups:
Creational Patterns: These patterns help in making objects in various situations.
- Singleton: For when you need only one of something.
- Factory Method: Creates objects from a bunch of choices, depending on the situation.
- Abstract Factory: Like a higher-level factory method, picking the right factory based on the situation.
- Builder: Puts together complex objects step by step, keeping the creation separate from how it’s used.
- Prototype: Makes a copy of something you already have.
Structural Patterns: These patterns help fit different parts together to create new functions.
- Adapter: Makes different things work together even if they don’t match perfectly.
- Decorator: Adds or changes stuff about an object without changing the whole thing.
- Composite: Helps build bigger things by nesting smaller parts.
- Facade: Simplifies using a complicated system by providing an easy way to interact with it.
- Flyweight: Saves time and memory by using things that are already there.
- Proxy: Stands in for another object, often to control access or add extras.
- Bridge: Separates how something works from how it looks so changes don’t mess everything up.
Behavioral Patterns: These patterns guide how objects talk to each other.
- Chain of Responsibility: Sends a request without knowing who exactly will handle it.
- Memento: Lets an object go back to a previous state.
- Template: A master plan with specifics added by special helpers.
- Observer: One thing tells lots of others about changes.
- State: Makes an object behave differently when things around it change.
- Iterator: Helps go through a bunch of things without knowing how they’re kept.
- Mediator: Helps objects chat without getting too tangled up.
- Command: Sets up a way to ask for things without knowing all the inner workings.
- Strategy: Picks one way of doing something from a bunch of choices.
- Visitor: Adds a new action without rewriting what it works on, shifting the action to another group.
- Interpreter: Does things in a special language, following its rules.
Imagine these design patterns as tools in an experienced developer’s toolbox. Each one tackles a specific kind of problem, making your code smarter and easier to manage. Just like using a recipe to cook, applying these patterns can make your code more understandable and lasting.
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