Question 74888 in Flutter Question posted in
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How to find the type of a element in a list in and flutter

I have a dynamic list as given below

List<dynamic> question = [" Elephants", "are", "the", 1, "land", 2, "on", 3];

I’m using a listview.builder to use this list on the screen to populate ui. What I want is to identify the int and show container with a red color and if it is string i want a container with blue color. How can i identiy the type of elements in the list

ListView.separated(
itemBuilder: (context, index) {
if (question.indexOf(int)) { // how to identify the type
return Container(color:Colors.red);
} else {
return Container(color:Colors.blue);
}
},
separatorBuilder: (context, index) => const SizedBox(
width: 6,
),
itemCount: question.length),
Tags:

3

Answers


  1. 0

    Use is for type checks.

    if(question[i] is int){

} else if(question[i] is String){

} else {

}
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  2. 0

    In Dart, you can check the type of an object using the is keyword or the runtimeType property.

    1. Using the is keyword: The is keyword is used to check if an object is of a certain type. It returns a boolean value indicating whether the object is of the specified type or not.

      if(question[i] is int) {

} else if(question[i] is String) {

}

    2. Using the runtimeType property: The runtimeType property returns the actual runtime type of an object.

      if(question[i].runtimeType==String) {

} else if(question[i].runtimeType==int) {

}
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  3. 0

    You can use is operator to check Type of any object

    Example:

    List<dynamic> question = [" Elephants", "are", "the", 1, "land", 2, "on", 3];

for(var element in question) {
   if(element is String) {
      // current element is String. Handle accordingly
   } else if (element is int) {
      // current element is int. Handle accordingly
   } else {
      // unknown or any other type. Handle accordingly
   }
}

    To use it in UI file you can check following example:

    ListView.separated(itemBuilder: (context, index) => question[index] is String ? Container(
   decoration: BoxDecoration(
    color: Colors.green,
   ),
   child: Center(
     child: Text("String"),
    ),
  ) : question[index] is int ? Container(
    decoration: BoxDecoration(
    color: Colors.yellow,
    ),
    child: Center(
     child: Text("int"),
    ),
  ) : Container(
    decoration: BoxDecoration(
    color: Colors.red,
    ),
    child: Center(
     child: Text("Unknown"),
    ),
  ), 
    itemCount: question.length);
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