What are the design patterns in Java?

Java design patterns include: 1. Singleton mode; 2. Factory mode; 3. Builder mode; 4. Prototype mode; 5. Adapter mode; 6. Appearance mode; 7. Observer mode; 8 , Strategy mode; 9. Template method mode; 10. Decorator mode; 11. Flyweight mode. Detailed introduction: 1. Singleton mode ensures that a class has only one instance and provides a global access point. This mode is usually used for resource management, such as database connections and caching; 2. Factory mode provides a way to create objects. Mechanism, through factory methods based on given parameters, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

Java design patterns are solutions to common problems in software development. They provide reusable design ideas and templates. The following are some common Java design patterns:

1. Singleton Pattern: The singleton pattern ensures that a class has only one instance and provides a global access point. This mode is usually used for resource management, such as database connections, caching, etc.

2. Factory Pattern: Factory Pattern provides a mechanism to create objects and returns an object based on given parameters through the factory method. This mode can avoid using the new operator directly to create objects, improving the flexibility and scalability of the code.

3. Builder Pattern: Builder Pattern provides the best way to create objects, gradually building an object through a specialized builder class. This pattern avoids a large number of parameters and configuration options when building objects.

4. Prototype Pattern: The prototype pattern allows you to create a new object by copying an existing object instead of recreating it. This mode makes object creation more efficient and avoids errors when copying objects.

5. Adapter Pattern: The adapter pattern converts the interface of a class into another interface expected by the client, so that the original interface cannot be used together due to incompatibility. Working classes are able to work together. This mode can solve problems caused by interface incompatibility.

6. Facade Pattern: Facade pattern provides a consistent interface for a set of interfaces in the subsystem, making the subsystem easier to use. This pattern simplifies the use of subsystems and provides a unified access point.

7. Observer Pattern: The Observer Pattern defines a one-to-many dependency relationship. When the state of an object changes, all objects that depend on it Objects are notified and updated automatically. This pattern can be used to implement event-driven systems.

8. Strategy Pattern: The strategy pattern defines a series of algorithms and encapsulates each algorithm so that they can be replaced with each other. This pattern allows the algorithm to be independent of the client using it.

9. Template Method Pattern: The template method pattern defines the skeleton of an algorithm in operation and defers certain steps to subclasses. This pattern allows subclasses to redefine specific steps of an algorithm without changing the structure of the algorithm.

10. Decorator Pattern: The decorator pattern dynamically adds some additional responsibilities to an object. In terms of adding functionality, the decorator pattern is more flexible than generating subclasses. This pattern can be used to extend the functionality of an object without modifying the original code.

11. Flyweight Pattern: Flyweight Pattern is a design technology used to reduce the number of objects in memory and thus save memory consumption. This pattern can be used to optimize the creation and destruction of large numbers of objects, thereby improving program performance and efficiency.

The above are some common Java design patterns. Each design pattern has its specific application scenarios and advantages. When using these design patterns, they need to be selected and implemented based on specific problems and needs.

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