In Dart, the containsValue method is used to check if the map contains a specific value.
bool containsValue(Object? value)
This method takes the argument, value, which represents the value that we want to check for.
This method returns true if the passed value is equal to any of the values in the map.
We use the == operator for that.
The code below demonstrates how to check if the HashMap contains an entry with a specific value:
import 'dart:collection';void main() {//create a new hashmap which can have string type as key, and int type as valueHashMap map = new HashMap<String, int>();// add two entries to the mapmap["one"] = 1;map["two"] = 2;print('The map is $map');// check if the map has a value 1print('map.containsValue(1) is ${map.containsValue(1)}');// check if the map has a value 3print('map.containsValue(2) is ${map.containsValue(3)}');}
Line 1: We import the collection library.
Line 4: We create a new HashMap object with the name map.
Lines 7 and 8: We add two new entries to the map.
Line 12: We used the containsValue method with 1 as an argument. This checks if the map has an entry with the value 1. In our code, there is an entry with the value 1. Hence, true is returned.
Line 13: We use the containsValue method with 3 as an argument. This checks if the map has an entry with the value 3. In our code, there is no entry with value 3 in the map so false is returned.