Remove items of SplayTreeSet that satisfy a condition in Dart
A
SplayTreeSetis a set of objects that can be ordered relative to each other.
We can use the removeWhere method to remove all the elements of the set that satisfy the provided test condition.
Syntax
void removeWhere( bool test(Element e) )
Argument
This method takes a test function, which takes one argument (current element value) and returns a boolean value. This method is invoked for each element of the set.
The removeWhere method will iterate the set and invoke the test function. If the test function returns True, then the current element will be removed from the set.
Return value
This method doesn’t return any value(s).
Code
The code written below demonstrates how we can use the removeWhere method to remove all the elements of the SplayTreeSet that satisfy a given condition:
import 'dart:collection';
void main() {
//create a new SplayTreeSet which can have int type elements
SplayTreeSet set = new SplayTreeSet<int>((a,b) => b.compareTo(a));
// add five elements to the set
set.add(5);
set.add(4);
set.add(3);
set.add(2);
set.add(1);
print('The set is $set');
// Remove the entry with odd value
set.removeWhere((element){
return element % 2 != 0;
});
print('The set is $set');
}Code explanation
-
Line 1: We import the
collectionlibrary. -
Line 4: We create a new
SplayTreeSetobject with the nameset. We pass acomparefunction as an argument. This function is used for maintaining the order of thesetelements. In our case, thecomparefunction orders the elements in a descending order. -
Lines 7–11: We add five new elements to the
set. Now, the set is{5,4,3,2,1}. -
Line 16: We use the
removeWheremethod with atestfunction as an argument. Thetestfunction returnsTrueif the element is anoddnumber. In our case, the elements5,3,1are odd numbers, so they are removed from theset. After the removal of the odd number values, thesetis{4,2}.
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