AMap of objects that can be ordered relative to each other.

The map is based on a self-balancing binary tree.It allows most single-entry operations in amortized logarithmic time.

Keys of the map are compared using thecompare function passed inthe constructor, both for ordering and for equality.If the map contains only the keya, thenmap.containsKey(b)will returntrue if and only ifcompare(a, b) == 0,and the value ofa == b is not even checked.If the compare function is omitted, the objects are assumed to beComparable, and are compared using theirComparable.compareTo method.Non-comparable objects (includingnull) will not work as keysin that case.

To allow callingoperator [],remove orcontainsKey with objectsthat are not supported by thecompare function, an extraisValidKeypredicate function can be supplied. This function is tested beforeusing thecompare function on an argument value that may not be aKvalue. If omitted, theisValidKey function defaults to testing if thevalue is aK.

Notice:Do not modify a map (add or remove keys) while an operationis being performed on that map, for example in functionscalled during aforEach orputIfAbsent call,or while iterating the map (keys,values orentries).

Example:

final planetsByMass = SplayTreeMap<double, String>((a, b) => a.compareTo(b));

To add data to a map, useoperator[]=,addAll oraddEntries.

planetsByMass[0.06] = 'Mercury';planetsByMass    .addAll({0.81: 'Venus', 1.0: 'Earth', 0.11: 'Mars', 317.83: 'Jupiter'});

To check if the map is empty, useisEmpty orisNotEmpty.To find the number of map entries, uselength.

print(planetsByMass.isEmpty); // falseprint(planetsByMass.length); // 5

TheforEach method calls a function for each key/value entry of the map.

planetsByMass.forEach((key, value) {  print('$key \t $value');  // 0.06    Mercury  // 0.11    Mars  // 0.81    Venus  // 1.0     Earth  // 317.83  Jupiter});

To check whether the map has an entry with a specific key, usecontainsKey.

final keyOneExists = planetsByMass.containsKey(1.0); // truefinal keyFiveExists = planetsByMass.containsKey(5); // false

To check whether the map has an entry with a specific value,usecontainsValue.

final earthExists = planetsByMass.containsValue('Earth'); // truefinal plutoExists = planetsByMass.containsValue('Pluto'); // false

To remove an entry with a specific key, useremove.

final removedValue = planetsByMass.remove(1.0);print(removedValue); // Earth

To remove multiple entries at the same time, based on their keys and values,useremoveWhere.

planetsByMass.removeWhere((key, value) => key <= 1);print(planetsByMass); // {317.83: Jupiter}

To conditionally add or modify a value for a specific key, depending onwhether there already is an entry with that key,useputIfAbsent orupdate.

planetsByMass.update(1, (v) => '', ifAbsent: () => 'Earth');planetsByMass.putIfAbsent(317.83, () => 'Another Jupiter');print(planetsByMass); // {1.0: Earth, 317.83: Jupiter}

To update the values of all keys, based on the existing key and value,useupdateAll.

planetsByMass.updateAll((key, value) => 'X');print(planetsByMass); // {1.0: X, 317.83: X}

To remove all entries and empty the map, useclear.

planetsByMass.clear();print(planetsByMass.isEmpty); // falseprint(planetsByMass); // {}

See also:

• Map, the general interface of key/value pair collections.
• HashMap is unordered (the order of iteration is not guaranteed).
• LinkedHashMap iterates in key insertion order.

Mixed-in types

• MapMixin<K,V>

Constructors

SplayTreeMap([intcompare(Kkey1,Kkey2)?,boolisValidKey(dynamicpotentialKey)?])

SplayTreeMap.from(Map<Object?,Object?>other, [intcompare(Kkey1,Kkey2)?,boolisValidKey(dynamicpotentialKey)?])

Creates aSplayTreeMap that contains all key/value pairs ofother.

factory

SplayTreeMap.fromIterable(Iterableiterable, {Kkey(dynamicelement)?,Vvalue(dynamicelement)?,intcompare(Kkey1,Kkey2)?,boolisValidKey(dynamicpotentialKey)?})

Creates aSplayTreeMap where the keys and values are computed from theiterable.

factory

SplayTreeMap.fromIterables(Iterable<K>keys,Iterable<V>values, [intcompare(Kkey1,Kkey2)?,boolisValidKey(dynamicpotentialKey)?])

Creates aSplayTreeMap associating the givenkeys tovalues.

factory

SplayTreeMap.of(Map<K,V>other, [intcompare(Kkey1,Kkey2)?,boolisValidKey(dynamicpotentialKey)?])

Creates aSplayTreeMap that contains all key/value pairs ofother.Example:

factory

Properties

entries→Iterable<MapEntry<K,V>>

The map entries of thisMap.

no setteroverride

hashCode→int

The hash code for this object.

no setterinherited

isEmpty→bool

Whether there is no key/value pair in the map.

no setteroverride

isNotEmpty→bool

Whether there is at least one key/value pair in the map.

no setteroverride

keys→Iterable<K>

The keys of thisMap.

no setteroverride

length→int

The number of key/value pairs in the map.

no setteroverride

runtimeType→Type

A representation of the runtime type of the object.

no setterinherited

values→Iterable<V>

The values of thisMap.

no setteroverride

Methods

addAll(Map<K,V>other)→ void

Adds all key/value pairs ofother to this map.

override

addEntries(Iterable<MapEntry<K,V>>newEntries)→ void

Adds all key/value pairs ofnewEntries to this map.

inherited

cast<RK,RV>()→Map<RK,RV>

Provides a view of this map as havingRK keys andRV instances,if necessary.

inherited

clear()→ void

Removes all entries from the map.

override

containsKey(Object?key)→bool

Whether this map contains the givenkey.

override

containsValue(Object?value)→bool

Whether this map contains the givenvalue.

override

firstKey()→ K?

The first key in the map.

firstKeyAfter(Kkey)→ K?

Get the first key in the map that is strictly larger thankey. Returnsnull if such a key was not found.

forEach(voidf(Kkey,Vvalue))→ void

Appliesaction to each key/value pair of the map.

override

lastKey()→ K?

The last key in the map.

lastKeyBefore(Kkey)→ K?

The last key in the map that is strictly smaller thankey.

map<K2,V2>(MapEntry<K2,V2>transform(Kkey,Vvalue))→Map<K2,V2>

Returns a new map where all entries of this map are transformed bythe givenconvert function.

inherited

noSuchMethod(Invocationinvocation)→ dynamic

Invoked when a nonexistent method or property is accessed.

inherited

putIfAbsent(Kkey,VifAbsent())→ V

Look up the value ofkey, or add a new entry if it isn't there.

override

remove(Object?key)→ V?

Removeskey and its associated value, if present, from the map.

override

removeWhere(booltest(Kkey,Vvalue))→ void

Removes all entries of this map that satisfy the giventest.

inherited

toString()→String

A string representation of this object.

inherited

update(Kkey,Vupdate(Vvalue), {VifAbsent()?})→ V

Updates the value for the providedkey.

override

updateAll(Vupdate(Kkey,Vvalue))→ void

Updates all values.

override

Operators

operator ==(Objectother)→bool

The equality operator.

inherited

operator [](Object?key)→ V?

The value for the givenkey, ornull ifkey is not in the map.

override

operator []=(Kkey,Vvalue)→ void

Associates thekey with the givenvalue.

override