What are the best practices for using the Strategy design pattern in Java?

What are the best practices for using the Strategy design pattern in Java?

The Strategy design pattern allows you to define a family of algorithms, encapsulate each one, and make them interchangeable. Best practices include: 1. Keep your strategies focused on a single responsibility. 2. Use interfaces to define the strategy contract. 3. Favor composition over inheritance. 4. Ensure strategies are stateless whenever possible.

Can you give an example of how to implement it?

Sure! Here's a simple example:

interface Strategy {
    int execute(int a, int b);
}

class AddStrategy implements Strategy {
    public int execute(int a, int b) {
        return a + b;
    }
}

class Context {
    private Strategy strategy;

    public Context(Strategy strategy) {
        this.strategy = strategy;
    }

    public int executeStrategy(int a, int b) {
        return strategy.execute(a, b);
    }
}

// Usage
Context context = new Context(new AddStrategy());
int result = context.executeStrategy(5, 3); // result is 8

What are some common pitfalls to avoid?

Common pitfalls include: 1. Overcomplicating the design by creating too many strategies. 2. Not adhering to the Open/Closed Principle, which can lead to difficulties in extending functionality. 3. Failing to document the purpose of each strategy, making it hard for others to understand their use.

How do I decide when to use the Strategy pattern?

Use the Strategy pattern when you have multiple algorithms for a specific task and want to switch between them dynamically. It's particularly useful when the algorithms are interchangeable and you want to avoid conditional statements in your code.