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ChildEventListener

interface ChildEventListener

Classes implementing this interface can be used to receive events about changes in the child locations of a given DatabaseReference ref. Attach the listener to a location using addChildEventListener and the appropriate method will be triggered when changes occur.

Summary

Public functions
`Unit`	`onCancelled(error: DatabaseError)` 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 rules.
`Unit`	`onChildAdded(snapshot: DataSnapshot, previousChildName: String?)` This method is triggered when a new child is added to the location to which this listener was added.
`Unit`	`onChildChanged(snapshot: DataSnapshot, previousChildName: String?)` This method is triggered when the data at a child location has changed.
`Unit`	`onChildMoved(snapshot: DataSnapshot, previousChildName: String?)` This method is triggered when a child location's priority changes.
`Unit`	`onChildRemoved(snapshot: DataSnapshot)` This method is triggered when a child is removed from the location to which this listener was added.

Public functions

onCancelled

fun onCancelled(error: DatabaseError): Unit

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 rules. For more information on securing your data, see: Security Quickstart

Parameters
`error: DatabaseError`	A description of the error that occurred

onChildAdded

fun onChildAdded(snapshot: DataSnapshot, previousChildName: String?): Unit

This method is triggered when a new child is added to the location to which this listener was added.

Parameters
`snapshot: DataSnapshot`	An immutable snapshot of the data at the new child location
`previousChildName: String?`	The key name of sibling location ordered before the new child. This will be null for the first child node of a location.

onChildChanged

fun onChildChanged(snapshot: DataSnapshot, previousChildName: String?): Unit

This method is triggered when the data at a child location has changed.

Parameters
`snapshot: DataSnapshot`	An immutable snapshot of the data at the new data at the child location
`previousChildName: String?`	The key name of sibling location ordered before the child. This will be null for the first child node of a location.

onChildMoved

fun onChildMoved(snapshot: DataSnapshot, previousChildName: String?): Unit

This method is triggered when a child location's priority changes. See setPriority and Ordered Data for more information on priorities and ordering data.

Parameters
`snapshot: DataSnapshot`	An immutable snapshot of the data at the location that moved.
`previousChildName: String?`	The key name of the sibling location ordered before the child location. This will be null if this location is ordered first.

onChildRemoved

fun onChildRemoved(snapshot: DataSnapshot): Unit

This method is triggered when a child is removed from the location to which this listener was added.

Parameters
`snapshot: DataSnapshot`	An immutable snapshot of the data at the child that was removed.