# Interface Observer

public interface Observer

`Observer` is the interface to be implemented by objects that receive notification of updates on an `Observable` object.

##### See also

- Observable

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `update(Observable observable, Object data)`
  This method is called if the specified `Observable` object's `notifyObservers` method is called (because the `Observable` object has been updated.

- ## Method Details

  - ### update

    void update(Observable observable, Object data)

    This method is called if the specified `Observable` object's `notifyObservers` method is called (because the `Observable` object has been updated.

    ###### Parameters

    - `observable`: the `Observable` object.

    - `data`: the data passed to `Observable#notifyObservers(Object)`.