ConnectionEventListener (Pusher Java Websocket API)

```
public interface ConnectionEventListener
```
Client applications should implement this interface if they wish to receive notifications when the state of a Connection changes or an error is thrown.
Implementations of this interface can be bound to the connection by calling Connection.bind(ConnectionState, ConnectionEventListener). The connection itself can be retrieved from the Pusher object by calling Pusher.getConnection().

Alternatively, you can bind your implementation of the interface and connect at the same time by calling Pusher.connect(ConnectionEventListener, ConnectionState...) .

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`onConnectionStateChange(ConnectionStateChange change)`	Callback that is fired whenever the `ConnectionState` of the `Connection` changes.
`void`	`onError(java.lang.String message, java.lang.String code, java.lang.Exception e)`	Callback that indicates either: An error message has been received from Pusher, or An error has occurred in the client library.

- Method Detail
  - onConnectionStateChange
```
void onConnectionStateChange(ConnectionStateChange change)
```
    Callback that is fired whenever the ConnectionState of the Connection changes. The state typically changes during connection to Pusher and during disconnection and reconnection.
    This callback is only fired if the ConnectionEventListener has been bound to the new state by calling Connection.bind(ConnectionState, ConnectionEventListener) with either the new state or ConnectionState.ALL.
    
    Parameters:
    
    change - An object that contains the previous state of the connection and the new state. The new state can be retrieved by calling ConnectionStateChange.getCurrentState().
  - onError
```
void onError(java.lang.String message,
             java.lang.String code,
             java.lang.Exception e)
```
    Callback that indicates either:
    
    An error message has been received from Pusher, or
    
    An error has occurred in the client library.
    
    All ConnectionEventListeners that have been registered by calling Connection.bind(ConnectionState, ConnectionEventListener) will receive this callback, even if the ConnectionEventListener is only bound to specific connection status changes.
    Parameters:
    
    message - A message indicating the cause of the error.
    
    code - The error code for the message. Can be null.
    
    e - The exception that was thrown, if any. Can be null.