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Dart – Spread Operator (…)

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  • Last Updated : 31 Jan, 2022
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In Dart, Spread Operator (…) and Null-aware Spread Operator (…?) are used for inserting multiple elements in a collection like Lists, Maps, etc.

Syntaxes:

  • Spread operator
...Data_structure
  • Null-aware Spread operator
...?Data_structure

Example 1: Using spread operators with List.

Dart




// main function start
void main() {
  
   // initialise a List l1
   List? l1 = ["Geeks","For","Geeks"];
    
  // initialize another List l2 using l1
  List? l2=["Wow",...l1,"is","amazing"];
  
   // print List l2
   print(l2);
}


Output :

[Wow, Geeks, For, Geeks, is, amazing]

Example 2: Using Spread operator with Map.

Dart




// main function start
  
void main() {
    
   // initialise a Map m1
   Map? m1 = {"name":"John","age":21};
    
  // initialize another Map m2 using m1
  Map? m2={"roll no":45,"class":12,...m1};
  
   // print Map m2
   print(m2);
}


Output :

{roll no: 45, class: 12, name: John, age: 21}

Example 3: Using spread operator with Sets.

Dart




// main function start
void main() {
    
  // first set s1  
  Set<int> s1 = {5, 4, 3};
  
  // second set s2
  Set<int> s2 = {3, 2, 1};
  
  // result Set
  Set<int> result = {...s1, ...s2};
  
  // print result set
  print(result);
}


Output:

{5,4,3,2,1}

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