Dyuichi Blog

javaimport java.util.HashMap;
import java.util.Map;

// Flyweight
interface Flyweight {
    void operation(int extrinsicState);
}

// Concrete Flyweight
class ConcreteFlyweight implements Flyweight {
    private String intrinsicState;
    public ConcreteFlyweight(String intrinsicState) {
        this.intrinsicState = intrinsicState;
    }
    @Override
    public void operation(int extrinsicState) {
        System.out.println("ConcreteFlyweight operation: (Extrinsic State: " + extrinsicState + ", Intrinsic State: " + intrinsicState + ")");
    }
}

// Flyweight Factory
class FlyweightFactory {
    private Map<String, Flyweight> flyweights = new HashMap<>();
    public Flyweight getFlyweight(String key) {
        if (flyweights.containsKey(key)) {
            return flyweights.get(key);
        } else {
            Flyweight flyweight = new ConcreteFlyweight(key);
            flyweights.put(key, flyweight);
            return flyweight;
        }
    }
}

// Client
public class FlyweightPattern {
    public static void main(String[] args) {
        FlyweightFactory factory = new FlyweightFactory();
        Flyweight flyweight1 = factory.getFlyweight("key1");
        Flyweight flyweight2 = factory.getFlyweight("key2");
        Flyweight flyweight3 = factory.getFlyweight("key1");
        flyweight1.operation(1);
        flyweight2.operation(2);
        flyweight3.operation(3);
    }
}