Class: Toybox.Lang.Dictionary

Inherits:

Toybox.Lang.Object

• Toybox.Lang.Object
• Toybox.Lang.Dictionary

Overview

A Dictionary is a hash table or associative array used to map keys to values.

Both the keys and values can be any Object type, though they do not all need to be of the same type. Objects used as a key should override the hashCode() method. Due to the nature of hash tables, the order of Dictionary elements are not guaranteed to match the insertion order. null cannot be used as a key.

See Also:

• Hash Table

Example:

import Toybox.System;
var myDict = {
    "One" => 1,
    "Two" => 2,
    "Three" => 3
};
System.println(myDict);         // {Two=>2, One=>1,Three=>3}
var keys = myDict.keys();       // [Two, One, Three]
var values = myDict.values();   // [2, 1, 3]

myDict.put("Four", 4);
System.println(myDict);         // {Two=>2, One=>1, Three=>3, Four=>4}
var numItems = myDict.size();   // 4

myDict = {};                    // Empty the dictionary
System.println(myDict.isEmpty()); // true

Since:

API Level 1.0.0

Instance Method Summary

• get(key)

  Retrieve a value from a Dictionary for a given key.

• hasKey(key) as Lang.Boolean

  Determine whether a key exists within a Dictionary.

• isEmpty() as Lang.Boolean

  Determine whether a Dictionary is empty.

• keys() as Lang.Array

  Retrieve the keys in the Dictionary.

• put(key, value) as Void

  Place a value in the Dictionary with a given key.

• remove(key) as Void

  Delete an item from a Dictionary.

• size() as Lang.Number

  Retrieve the number of elements in a Dictionary.

• toString() as Lang.String

  Convert a Dictionary to a String.

• values() as Lang.Array

  Retrieve the values in the Dictionary.

Instance Method Details

get(key)

Retrieve a value from a Dictionary for a given key.

Parameters:

• key —

  The key to check against

Returns:

• The value for the specified key, or null if the key does not exist

Since:

API Level 1.0.0

hasKey(key) as Lang.Boolean

Determine whether a key exists within a Dictionary.

Parameters:

• key —

  The key to check against

Returns:

• Lang.Boolean —

  true if the key is in the Dictionary, otherwise false

Since:

API Level 1.0.0

isEmpty() as Lang.Boolean

Determine whether a Dictionary is empty.

Returns:

• Lang.Boolean —

  true if the Dictionary is empty, otherwise false

Since:

API Level 1.0.0

keys() as Lang.Array

Retrieve the keys in the Dictionary.

Returns:

• Lang.Array —

  An Array of keys in the Dictionary

Since:

API Level 1.0.0

put(key, value) as Void

Place a value in the Dictionary with a given key.

Parameters:

• key —

  The key for the value being inserted into the Dictionary

• value —

  The value to insert into the Dictionary

Since:

API Level 1.0.0

remove(key) as Void

Delete an item from a Dictionary.

Parameters:

• key —

  The key of the value to be removed

Since:

API Level 1.0.0

size() as Lang.Number

Retrieve the number of elements in a Dictionary.

Returns:

• Lang.Number —

  The number of elements in the Dictionary

Since:

API Level 1.0.0

toString() as Lang.String

Convert a Dictionary to a String.

Due to the nature of hash tables, the order of Dictionary elements are not guaranteed to match the insertion order when converting to a String.

Example:

import Toybox.System;
myDict = {
    "One" => 1,
    "Two" => 2,
    "Three" => 3
};
System.println(myDict.get("One"));        // prints 1

var myString = myDict.toString();
System.println(myString);                 // "{Two=>2, One=>1, Three=>}"
System.println(myString.get("One"));      // Symbol Not Found Error
System.println(myString.substring(0, 5)); // "{Two="

Returns:

• Lang.String —

  A String representation of the Dictionary

See Also:

• Hash Tables

Since:

API Level 1.0.1

values() as Lang.Array

Retrieve the values in the Dictionary.

Returns:

• Lang.Array —

  An Array of values in the Dictionary

Since:

API Level 1.0.0