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io.realm

Interface RealmCollection

On this page

  • io.realm
  • Method Summary
  • Inherited Methods
  • Method Detail
  • average
  • contains
  • deleteAllFromRealm
  • isLoaded
  • isManaged
  • isValid
  • load
  • max
  • maxDate
  • min
  • minDate
  • sum
  • where

io.realm

Implemented interfaces:

  • java.util.Collection

  • java.lang.Iterable

RealmCollection is the root of the collection hierarchy that Realm supports. It defines operations on data collections and the behavior that they will have in all implementations of RealmCollection s.

Realm collections are "live" views to the underlying data. This means that they automatically will be kept up to date. As a consequence, using methods like Collections.unmodifiableCollection(Collection) will not prevent a collection from being modified.

Method Summary

Modifier and Type
Method and Description
public double
average (
String fieldName
)

Returns the average of a given field.

public boolean
contains (
Object object
)

Tests whether this Collection contains the specified object.

public boolean
deleteAllFromRealm ()

This deletes all objects in the collection from the underlying Realm as well as from the collection.

public boolean
isLoaded ()

Checks if a collection has finished loading its data yet.

public boolean
isManaged ()

Checks if the collection is managed by Realm.

public boolean
isValid ()

Checks if the collection is still valid to use, i.e., the io.realm.Realm instance hasn't been closed.

public boolean
load ()

Blocks the collection until all data are available.

public Number
max (
String fieldName
)

Finds the maximum value of a field.

public Date
maxDate (
String fieldName
)

Finds the maximum date.

public Number
min (
String fieldName
)

Finds the minimum value of a field.

public Date
minDate (
String fieldName
)

Finds the minimum date.

public Number
sum (
String fieldName
)

Calculates the sum of a given field.

public RealmQuery
where ()

Returns a RealmQuery , which can be used to query for specific objects from this collection.

Inherited Methods

Method Detail

average

public double average (
String fieldName
)

Returns the average of a given field.

Parameters

  • fieldName - the field to calculate average on. Only number fields are supported.

Returns

the average for the given field amongst objects in query results. This will be of type double for all types of number fields. If no objects exist or they all have null as the value for the given field, 0 will be returned. When computing the average, objects with null values are ignored.

Throws

contains

public boolean contains (
Object object
)

Tests whether this Collection contains the specified object. Returns true if and only if at least one element elem in this Collection meets following requirement: (object==null ? elem==null : object.equals(elem)) .

Parameters

  • object - the object to search for.

Returns

true if object is an element of this Collection , false otherwise.

Throws

  • NullPointerException - if the object to look for is null and this Collection doesn't support null elements.

deleteAllFromRealm

public boolean deleteAllFromRealm ()

This deletes all objects in the collection from the underlying Realm as well as from the collection.

Returns

true if objects was deleted, false otherwise.

Throws

isLoaded

public boolean isLoaded ()

Checks if a collection has finished loading its data yet.

Returns

true if data has been loaded and is available, false if data is still being loaded.

isManaged

public boolean isManaged ()

Checks if the collection is managed by Realm. A managed collection is just a wrapper around the data in the underlying Realm file. On Looper threads, a managed collection will be live-updated so it always points to the latest data. Managed collections are thread confined so that they cannot be accessed from other threads than the one that created them.If this method returns false , the collection is unmanaged. An unmanaged collection is just a normal java collection, so it will not be live updated.

Returns

true if this is a managed RealmCollection , false otherwise.

isValid

public boolean isValid ()

Checks if the collection is still valid to use, i.e., the io.realm.Realm instance hasn't been closed. It will always return true for an unmanaged collection.

Returns

true if it is still valid to use or an unmanaged collection, false otherwise.

load

public boolean load ()

Blocks the collection until all data are available.

Returns

true if the data could be successfully loaded, false otherwise.

max

public Number max (
String fieldName
)

Finds the maximum value of a field.

Parameters

  • fieldName - the field to look for a maximum on. Only number fields are supported.

Returns

if no objects exist or they all have null as the value for the given field, null will be returned. Otherwise the maximum value is returned. When determining the maximum value, objects with null values are ignored.

Throws

maxDate

public Date maxDate (
String fieldName
)

Finds the maximum date.

Parameters

  • fieldName - the field to look for the maximum date. If fieldName is not of Date type, an exception is thrown.

Returns

if no objects exist or they all have null as the value for the given date field, null will be returned. Otherwise the maximum date is returned. When determining the maximum date, objects with null values are ignored.

Throws

min

public Number min (
String fieldName
)

Finds the minimum value of a field.

Parameters

  • fieldName - the field to look for a minimum on. Only number fields are supported.

Returns

if no objects exist or they all have null as the value for the given field, null will be returned. Otherwise the minimum value is returned. When determining the minimum value, objects with null values are ignored.

Throws

minDate

public Date minDate (
String fieldName
)

Finds the minimum date.

Parameters

  • fieldName - the field to look for the minimum date. If fieldName is not of Date type, an exception is thrown.

Returns

if no objects exist or they all have null as the value for the given date field, null will be returned. Otherwise the minimum date is returned. When determining the minimum date, objects with null values are ignored.

Throws

sum

public Number sum (
String fieldName
)

Calculates the sum of a given field.

Parameters

  • fieldName - the field to sum. Only number fields are supported.

Returns

the sum. If no objects exist or they all have null as the value for the given field, 0 will be returned. When computing the sum, objects with null values are ignored.

Throws

where

public RealmQuery where ()

Returns a RealmQuery , which can be used to query for specific objects from this collection.

Returns

a RealmQuery object.

Throws

Tip

See also:

Back

RealmChangeListener

Next

RealmConfiguration