Flutter - type 'List' is not a subtype of type 'List'

Question

I was trying to use a ListView.builder to display a list of Images dynamically as they are saved into an array of type File,

Here is my code :

List viewImg = [].toList();

_imgFromGallery() async {
    File image = await ImagePicker.pickImage(
        source: ImageSource.gallery, imageQuality: 50);

    setState(() {
      _image = image;
      viewImg.add(image);
    });
  }

    ListView.builder(
                          itemCount: viewImg.length,
                          itemBuilder: (BuildContext context, int index) {
                            return new SingleChildScrollView(
                              physics: ScrollPhysics(),
                              child: Column(children: [
                                Container(
                                margin:EdgeInsets.only(top30),
                                  width: size.width * .8,
                                  height: 149,
                                  decoration: BoxDecoration(
                                      image: DecorationImage( 
                                       image:FileImage(viewImg[index]),
                                  )),
                                ),

Every time I run it I get the error:

 type 'List' is not a subtype of type 'List'.

Please help me out and thanks in advance.

user_5177596 · Answer

Simply replace

List viewImg = [].toList();

with this

List viewImg = [];

user_6618622 · Answer

When you say:

List viewImg = [].toList();

You're actually creating a List and assigning it to a List which is an error. What you can do is, either use List.from

List viewImg = List.from([].toList());

or

List viewImg = [].toList();

Those were just bad ways (because you were just copying the List) to do simple things, you should rather use:

List viewImg = [];

or

var viewImg = [];

Flutter - type 'List<dynamic>' is not a subtype of type 'List<File>'

2 Answers