List in Dart

List In Dart

If you want to store multiple values in the same variable, you can use List. List in dart is similar to Arrays in other programming languages. E.g. to store the names of multiple students, you can use a List. The List is represented by Square Braces[].

How To Create List

You can create a List by specifying the initial elements in a square bracket. Square bracket [] is used to represent a List.

// Integer List
List<int> ages = [10, 30, 23];

// String List
List<String> names = ["Raj", "John", "Rocky"];

// Mixed List
var mixed = [10, "John", 18.8];

Types Of Lists

  • Fixed Length List
  • Growable List [Mostly Used]

Fixed Length List

The fixed-length Lists are defined with the specified length. You cannot change the size at runtime. This will create List of 5 integers with the value 0.

void main() {  
   var list = List<int>.filled(5,0);  
   print(list);  
}

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Info

Note: You cannot add a new item to Fixed Length List, but you can change the values of List.

Growable List

A List defined without a specified length is called Growable List. The length of the growable List can be changed in runtime.

void main() {  
   var list1 = [210,21,22,33,44,55];  
   print(list1);  
}  

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Access Item Of List

You can access the List item by index. Remember that the List index always starts with 0.

void main() {
  var list = [210, 21, 22, 33, 44, 55];

  print(list[0]);
  print(list[1]);
  print(list[2]);
  print(list[3]);
  print(list[4]);
  print(list[5]);
}

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Get Index By Value

You can also get the index by value.

void main() {
  var list = [210, 21, 22, 33, 44, 55];

  print(list.indexOf(22));
  print(list.indexOf(33));
}

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Find The Length Of The List

You can find the length of List by using .length property.

void main(){  
   List<String> names = ["Raj", "John", "Rocky"];
   print(names.length);
 }

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Info

Note: Remember that List index starts with 0 and length always starts with 1.

Changing Values Of List

You can also change the value of List. You can do it by listName[index]=value;. For more, see the example below.

void main(){  
   List<String> names = ["Raj", "John", "Rocky"];
   names[1] = "Bill";
   names[2] = "Elon";
   print(names);
}

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Mutable And Immutable List

A mutable List means they can change after the declaration, and an immutable List means means they can’t change after the declaration


List<String> names = ["Raj", "John", "Rocky"]; // Mutable List
names[1] = "Bill"; // possible
names[2] = "Elon"; // possible
    
const List<String> names = ["Raj", "John", "Rocky"]; // Immutable List
names[1] = "Bill"; // not possible
names[2] = "Elon"; // not possible

List Properties In Dart

  • first: It returns the first element in the List.
  • last: It returns the last element in the List.
  • isEmpty: It returns true if the List is empty and false if the List is not empty.
  • isNotEmpty: It returns true if the List is not empty and false if the List is empty.
  • length: It returns the length of the List.
  • reversed: It returns a List in reverse order.
  • Single: It is used to check if the List has only one element and returns it.

Access First And Last Elements Of List

You can access the first and last elements in the List by:

void main() {
   List<String> drinks = ["water", "juice", "milk", "coke"];
   print("First element of the List is: ${drinks.first}");
   print("Last element of the List is: ${drinks.last}");
}  

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Check The List Is Empty Or Not

You can also check List contain any elements inside it or not. It will give result either in true or in false.

void main() {
   List<String> drinks = ["water", "juice", "milk", "coke"];
   List<int>  ages = [];
   print("Is drinks Empty: "+drinks.isEmpty.toString());
   print("Is drinks not Empty: "+drinks.isNotEmpty.toString());
   print("Is ages Empty: "+ages.isEmpty.toString());
   print("Is ages not Empty: "+ages.isNotEmpty.toString());
   
}  

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Reverse List In Dart

You can easily reverse List by using .reversed properties. Here is an example below:

void main() {
   List<String> drinks = ["water", "juice", "milk", "coke"];
   print("List in reverse: ${drinks.reversed}");
}  

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Adding Item To List

Dart provides four methods to insert the elements into the Lists. These methods are given below.

Method Description
add() Add one element at a time and returns the modified List object.
addAll() Insert the multiple values to the given List, and each value is separated by the commas and enclosed with a square bracket ([]).
insert() Provides the facility to insert an element at a specified index position.
insertAll() Insert the multiple value at the specified index position.

Example 1: Add Item To List

In this example below, we are adding an item to evenList using add() method.

void main() {  
    var evenList = [2,4,6,8,10];  
    print(evenList);  
    evenList.add(12);  
    print(evenList);  
}  

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Example 2: Add Items To List

In this example below, we are adding items to evenList using addAll() method.

void main() {
  var evenList = [2, 4, 6, 8, 10];
  print(evenList);
  evenList.addAll([12, 14, 16, 18]);
  print(evenList);
}

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Example 3: Insert Item To List

In this example below, we are adding an item to myList using insert() method.

void main() {
  List myList = [3, 4, 2, 5];
  print(myList);
  myList.insert(2, 15);
  print(myList);
}

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Example 4: Insert Items To List

In this example below, we are adding items to myList using insertAll() method.

void main() {
  var myList = [3, 4, 2, 5];
  print(myList);
  myList.insertAll(1, [6, 7, 10, 9]);
  print(myList);
}
  

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Replace Range Of List

You can also replace the range of the List. For more, see the example below.

void main() {
  var list = [10, 15, 20, 25, 30];
  print("List before updation: ${list}");
  list.replaceRange(0, 4, [5, 6, 7, 8]);
  print("List after updation using replaceAll() function : ${list}");
}

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Removing List Elements

Method Description
remove() Removes one element at a time from the given List.
removeAt() Removes an element from the specified index position and returns it.
removeLast() Remove the last element from the given List.
removeRange() Removes the item within the specified range.

Example 1: Removing List Item From List

In this example below, we are removing item of List using remove() method.

void main() {
  var list = [10, 20, 30, 40, 50];
  print("List before removing element : ${list}");
  list.remove(30);
  print("List after removing element : ${list}");
}

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Example 2: Removing List Item From List

In this example below, we are removing item of List using removeAt() method.

void main() {
  var list = [10, 11, 12, 13, 14];
  print("List before removing element : ${list}");
  list.removeAt(3);
  print("List after removing element : ${list}");
}

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Example 3: Removing Last Item From List

In this example below, we are removing last item of List using removeLast() method.

void main() {
  var list = [10, 20, 30, 40, 50];
  print("List before removing element:${list}");
  list.removeLast();
  print("List after removing last element:${list}");
}

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Example 4: Removing List Range From List

In this example below, we are removing the range of items of List using removeRange() method.

void main() {
  var list = [10, 20, 30, 40, 50];
  print("List before removing element:${list}");
  list.removeRange(0, 3);
  print("List after removing range element:${list}");
}

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Loops In List

You can use for loop, for each loop, or any other type of loop.

void main() {
  List<int> list = [10, 20, 30, 40, 50];
  list.forEach((n) => print(n));
}

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Multiply All Value By 2 Of All List

This example below multiply value of List item by 2.

void main() {
  List<int> list = [10, 20, 30, 40, 50];
  var douledList = list.map((n) => n * 2);

  print((douledList));
}

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Combine Two Or More List In Dart

You can combine two or more Lists in dart by using spread syntax.

void main() {
  List<String> names = ["Raj", "John", "Rocky"];
  List<String> names2 = ["Mike", "Subash", "Mark"];

  List<String> allNames = [...names, ...names2];
  print(allNames);
}

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Conditions In List

You can also use conditions in List. Here sad = false so cart doesn’t contain Beer in it.

void main() {
  bool sad = false;
  var cart = ['milk', 'ghee', if (sad) 'Beer'];
  print(cart);
}
 

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Where In List Dart

You can use where with List to filter specific items. Here in this example, even numbers are only filtered.

void main(){
List<int> numbers = [2,4,6,8,10,11,12,13,14];

List<int> even = numbers.where((number)=> number.isEven).toList(); 
print(even);
}

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Info

Note: Choose Lists if order matters. You can easily add items to the end. Searching can be slow when the List size is big.

Video

Watch our video on the list in Dart.