How to check and compare two different list

user_15820705 0
Viewed 366

I have 2 list:

  List<Users> users = List();
  List<String> allIds = List();

users.id has following data [1,2,3,4,9] and allIds has following data [12,1,2,3,4,5,6,7,8,9,90,50,20]

Now I want to know whether all data of users.id exist in allIds list or not.

dart flutter
4 Answers
final allUsersID = users.every((Users u) => allIds.contains(u.id));

if (allUsersID) {
 print('all data of users.id EXIST in allIds list');
} else {
 print('all data of users.id DO NOT EXIST in allIds list!');
}
user_142399570

Use this code:

List<String> ids=users.map((e) => e.id).tolist();
List<String> union=[...ids, ...allIds ].toSet().toList();
if(union.length==allIds.length)
{
   //all data of users.id exist in allIds
}
user_32573860

Since there are two good answers I just want to add another solution. Remove all user's id from allIds then if the allIds is empty so 2 lists are equal.

 for (final user in users) {
   allIds.remove(user.id);
 }
 
 if (allIds.isEmpty) {
   // 2 lists are equal
 } else {
   // 2 lists are not equal and you can access all ids not found in your user's list
 }
user_63789490

And here is a solution using Set class containsAll method:

allIds.toSet().containsAll(users.map((x) => x.id))
user_101185050
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