Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
How to work with Maps in Kotlin?
A Map is a collection where data is stored as a key-value pair and the corresponding keys have to be unique. A HashMap is a collection class based on MutableMap interface and it does that by implementing the MutableMap interface of HashTable.
Kotlin provides four types of constructors to define and manipulate a HashMap.
Example – Map Creation and Iteration in Kotlin
In this example, we will be creating a Map called "subject" and we will be iterating through it.
fun main(args: Array<String>) {
// Declare HashMap
var subject : HashMap<String, Int>
= HashMap<String, Int> ();
// Assigning value to HashMap
subject.put("Java" , 1);
subject.put("Kotlin" , 2);
subject.put("Python" , 3);
subject.put("SQL" , 4);
// iterate using forEach
println("------iterate using forEach Method---------
")
subject.forEach { (k, v) ->
println(" Subject Name -> $k and its preference -> $v")
}
}Output
It will produce the following output −
------iterate using forEach Method--------- Subject Name -> Java and its preference -> 1 Subject Name -> Kotlin and its preference -> 2 Subject Name -> Python and its preference -> 3 Subject Name -> SQL and its preference -> 4
Example – Removing a value from a Map in Kotlin
In order to remove a value from a Map, we can use the remove() function.
fun main(args: Array<String>) {
// Declare the HashMap
var subject : HashMap<String, Int>
= HashMap<String, Int> ();
// Assigning value to HashMap
subject.put("Java" , 1);
subject.put("Kotlin" , 2);
subject.put("Python" , 3);
subject.put("SQL" , 4);
// Remove
subject.remove("SQL",4)
// iterate using forEach
println("------iterate using forEach Method---------
")
subject.forEach { (k, v) ->
println(" Subject Name -> $k and its preference -> $v")
}
}Output
It will produce the following output −
------iterate using forEach Method--------- Subject Name -> Java and its preference -> 1 Subject Name -> Kotlin and its preference -> 2 Subject Name -> Python and its preference -> 3
Updated on: 16-Mar-2022
189 Views
Advertisements