public interface

# ValueEventListener

com.google.firebase.database.ValueEventListener

## Class Overview

Classes implementing this interface can be used to receive events about data changes at a location. Attach the listener to a location user `addValueEventListener(ValueEventListener)`.

## Summary

Public Methods
abstract void | onCancelled(DatabaseError error) This method will be triggered in the event that this listener either failed at the server, or is removed as a result of the security and Firebase Database rules.
abstract void | onDataChange(DataSnapshot snapshot) This method will be called with a snapshot of the data at this location.

## Public Methods

#### public abstract void onCancelled (DatabaseError error)

This method will be triggered in the event that this listener either failed at the server, or is removed as a result of the security and Firebase Database rules. For more information on securing your data, see: Security Quickstart

##### Parameters

error | A description of the error that occurred

#### public abstract void onDataChange (DataSnapshot snapshot)

This method will be called with a snapshot of the data at this location. It will also be called each time that data changes.

##### Parameters

snapshot | The current data at the location