Dart Map is an object that stores data in the form of a key-value pair. Each value is associated with its key, and it is used to access its corresponding value. Both keys and values can be any type. In Dart Map, each key must be unique, but the same value can occur multiple times. The Map representation is quite similar to Python Dictionary. The Map can be declared by using curly braces {} ,and each key-value pair is separated by the commas(,). The value of the key can be accessed by using a square bracket([]).<\/p>\n\n\n\n
Dart Map can be defined in two methods.<\/p>\n\n\n\n
The syntax of declaring Dart Map is given below.<\/p>\n\n\n\n
To declare a Map using map literal, the key-value pairs are enclosed within the curly braces “{}” and separated by the commas. The syntax is given below.<\/p>\n\n\n\n
Syntax –<\/strong><\/p>\n\n\n\n <\/a><\/a><\/a><\/p>\n\n\n\n Example – 1:<\/strong><\/a><\/a><\/a><\/p>\n\n\n\n Output:<\/strong><\/p>\n\n\n\n Example – 2: Adding value at runtime<\/strong><\/a><\/a><\/a><\/p>\n\n\n\n Output:<\/strong><\/p>\n\n\n\n Explanation –<\/strong><\/p>\n\n\n\n In the above example, we declared a Map of a student<\/strong> name. We added the value at runtime by using a square bracket and passed the new key as a course<\/strong> associated with its value.<\/p>\n\n\n\n To declare the\u00a0Dart\u00a0Map using map constructor can be done in two ways. First, declare a map using\u00a0map()<\/strong>\u00a0constructor. Second, initialize the map. The syntax is given below.<\/p>\n\n\n\n Syntax –<\/strong><\/p>\n\n\n\n <\/a><\/a><\/a><\/p>\n\n\n\n After that, initialize the values.<\/a><\/a><\/a><\/p>\n\n\n\n Example – 1: Map constructor<\/strong><\/a><\/a><\/a><\/p>\n\n\n\n Output:<\/strong><\/p>\n\n\n\n The dart:core:package has Map class which defines following properties.<\/p>\n\n\n\nvar map_name = {key1:value1, key2:value2 [.......,key_n: value_n]} <\/code><\/pre>\n\n\n\nvoid main() { \n var student = {'name':'Tom','age':'23'}; \n print(student); \n} <\/code><\/pre>\n\n\n\n{name: Tom, age: 23}\n<\/code><\/pre>\n\n\n\nvoid main() { \n var student = {'name':' tom', 'age':23}; \n student['course'] = 'B.tech'; \n print(student); \n} <\/code><\/pre>\n\n\n\n{name: tom, age: 23, course: B.tech}\n<\/code><\/pre>\n\n\n\nUsing Map Constructor<\/h3>\n\n\n\n
var map_name = new map() <\/code><\/pre>\n\n\n\nvoid main() { \n var student = new Map(); \n student['name'] = 'Tom'; \n student['age'] = 23; \n student['course'] = 'B.tech'; \n student['Branch'] = 'Computer Science'; \n print(student); \n} <\/code><\/pre>\n\n\n\n{name: Tom, age: 23, course: B.tech, Branch: Computer Science}\n<\/code><\/pre>\n\n\n\nNote – A map value can be any object including NULL.<\/h4>\n\n\n\n
Map Properties<\/h2>\n\n\n\n