CODEWITHSUNDEEP
listflutterdartrange
Mayur Agarwal
Mayur Agarwal

Reputation: 1834

How to remove a range in list depending on a condition in dart?

I made a list to separate to different lists of integers for a flutter project. Now I want to remove all integers after the last null value. How can I do that ?

void main() {
  List<int> v =[];
  for(int i=0; i<3; i++){
    for(int j=0; j<4; j++){
      v.add(1);
    }
    v.add(null);
  }
  for(int i=0; i<12; i++){
    print(v[i]);
  }
}

Upvotes: 1

Views: 2614

Answers (3)

Mayur Agarwal
Mayur Agarwal

Reputation: 1834

We can simply do that by, taking another list and storing the reverse of the list v in the new list. Then find the index of the first null in the new list. Then the index of the final null will be, Let the index of the null value came out to be n, then the value of the last null value in the list v will be, v.length - n + 1 for example,

 rev = v.reversed;
                int i;
                for (i = 0; i < rev.length; i++) {
                  if (rev[i] == null) {
                    break;
                  }
                }

Then the index will be v.length - i + 1. Now, just use sublist function in Dart.

Upvotes: 0

Kalpesh Dabhi
Kalpesh Dabhi

Reputation: 802

if you need to remove ranger data from list then you can use removeWhere , using this method you can remove ranger data based in condition

void main() {
List<int> v =[];
for(int i=0; i<3; i++){
  for(int j=0; j<4; j++){
   v.add(1);
  }
  v.add(null);
  v.removeWhere((x) => x is int);
 }
 for(int i=0; i<v.length; i++){
  print(v[i]);
 }
}

Upvotes: 1

Mobina
Mobina

Reputation: 7119

You can find the index of the last occurrence of null in the list and make a sublist starting from 0 to that index (+1 is used to include the last null value in the sublist):

  List<int> v2 = v.sublist(0, v.lastIndexOf(null) + 1);
  for(int i=0; i<v2.length; i++){
    print(v2[i]);
  }

Upvotes: 1

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