# Aggregation

A relationship where one object uses another object that can exist independently.

## What is **Aggregation** in Java?

**Aggregation** — A relationship where one object uses another object that can exist independently.

```java
class Engine {
    String start() {
        return "Started";
    }
}

class Car {
    private final Engine engine = new Engine();

    String drive() {
        return engine.start();
    }
}
```

Level: Journeyman · [More Java terms at this level](https://www.ask-codey.com/glossary/subjects/java/journeyman)

Updated: September 27, 2026

## In other subjects

- [Aggregation in OOP](https://www.ask-codey.com/glossary/aggregation-oop)

Source: https://www.ask-codey.com/glossary/aggregation