Question 79812 in Flutter Question posted in
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How to remove one instance of an object name with ".removeWhere" instead of all the elements in a list in Flutter

For example,
Lets say you have a list of apples

List<String> apples = ['green', 'red','red', 'yellow']

And you want to remove just one red apple using .removeWhere

apples.removeWhere((element => element == 'red));

however, this removes all instances of ‘red’ when I only want to remove one of them! Any solutions?

Tags:

3

Answers


  1. 0

    you could use directly the remove method on your list:

       List<String> apples = ['green', 'red','red', 'yellow'];    
   apples.remove("red");
   print(apples); // [green, red, yellow]
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  2. 0

    And if you want to use it like you’re using the removeWhere method, you can use this extension method :

    Add this on the global scope (outside your classes, just put it anywhere else you want)

    extension RemoveFirstWhereExt<T> on List<T> {
  void removeFirstWhere(bool Function(T) fn) {
    bool didFoundFirstMatch = false;
    for(int index = 0; index < length; index +=1) {
      T current = this[index];
      if(fn(current) && !didFoundFirstMatch) {
        didFoundFirstMatch = true;
        remove(current);
        continue;
      }
      
    }        
  }
}

    Then you can use it like this:

       List<String> apples = ['green', 'red','red', 'yellow'];    
   apples.removeFirstWhere((element) => element == 'red');
   print(apples); // [green, red, yellow]
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  3. 0

    A third solution, if you want to remove all occurrences in your List so every String should be there only once, you can simply make it a Set :

     List<String> apples = ['green', 'red','red', 'yellow', 'green'];
 print(apples.toSet().toList()); // [green, red, yellow]
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