# 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)`.