Application and Practice of Design Patterns in Java

Design patterns are a summary of best practices commonly used in software design. They provide templates for solving common design problems. In the Java programming language, the application of design patterns can greatly improve the quality of code, making it easier to maintain and extend. This article will explore several common design patterns and provide specific application examples of them in Java.

Singleton Pattern

The factory pattern provides a way to create objects without exposing the creation logic, typically by using a common interface to create a series of related or dependent objects.

Implementation Example :

java

Dark version

interface Shape {
    void draw();
}class Rectangle implements Shape {
    @Override
    public void draw() {
        System.out.println(     Draw a rectangle     );
    }
}class Circle implements Shape {
    @Override
    public void draw() {
        System.out.println(     Draw a circle     );
    }
}class ShapeFactory {
    public Shape getShape(String shapeType) {
        if ("CIRCLE".equals(shapeType)) {
            return new Circle();
        } else if ("RECTANGLE".equals(shapeType)) {
            return new Rectangle();
        }
        return null;
    }
}

Observer Pattern

Design patterns provide standard solutions for solving specific problems, making code more modular and easy to understand. However, excessive use of design patterns may lead to overly complex systems, so when choosing whether to use design patterns, flexible decisions should be made based on the actual situation of the project.