Suggest an edit

Improve this article

Refine the answer for “What problem does the Flyweight pattern solve?”. Your changes go to moderation before they’re published.

Approval required

Content

What you’re changing

Title (EN)

Short answer (EN)

Shown above the full answer for quick recall.

Answer (EN)

**Flyweight** solves the problem of **excessive memory consumption**, which arises when a system needs to create a **huge number of objects of the same type** that contain repeated data.

---

### 1. **The Essence of the Problem**

When millions of objects have identical fields (for example, color, font, texture), storing this data in every instance becomes inefficient.
Memory is spent duplicating the same information.

---

### 2. **What Flyweight Does**

The pattern splits an object's state into:

- **intrinsic** - shared across all instances,
- **extrinsic** - unique and passed in from outside at the point of use.

The intrinsic state is stored **in a single shared object** that is **reused by many clients**.

---

### 3. **Example (Java)**

```java
class TreeType {
    private String name;
    private String color;
    private String texture;

public void draw(int x, int y) {
        System.out.println("Drawing " + name + " at (" + x + "," + y + ")");
    }
}

class TreeFactory {
    private static Map<String, TreeType> cache = new HashMap<>();

public static TreeType getTreeType(String name, String color, String texture) {
        String key = name + color + texture;
        return cache.computeIfAbsent(key, k -> new TreeType(name, color, texture));
    }
}

class Tree {
    private int x, y; // extrinsic state
    private TreeType type; // intrinsic state (shared object)
}
```

Here, millions of `Tree` objects use the same `TreeType` (color, texture, shape).

---

### 4. **The Result**

- Memory savings: the shared state is stored in one place.
- Fast work with large collections of objects of the same type.

---

### 5. **When to Apply It**

- In systems with a large number of objects of the same type (graphics, game scenes, glyph caches, text editors).
- When most of the objects' data repeats.

---

**Summary:**
**Flyweight** solves the problem of **excessive data duplication**,
letting many objects **share common state** and thereby **sharply reduce memory consumption**.

Markdown · drag & drop images · ⌘B / ⌘I shortcuts313 words

For the reviewer

Note to the moderator (optional)

Visible only to the moderator. Helps review go faster.