Flutter - How check string value from sharedPreferences

Question

How check string value from sharedPreferences list is null or empty? If null or empty go to Login page else print value.

SharedPreferences sharedPreferences = await SharedPreferences.getInstance();
final myStringList = sharedPreferences.getStringList('my_sharedPreferences_list') ?? [];

if ( **myStringList[0]  is null or empty**   ) {
  print('> EMAIL not found!');
  Navigator.of(context).pushReplacement(MaterialPageRoute(
      builder: (context) => Login()
  ));
}
else { print(myStringList[0].toString()); }

Answer 1

getStringList returns nullable list of String List<String>? . You can simply check

SharedPreferences sharedPreferences = await SharedPreferences.getInstance();
final myStringList =
        sharedPreferences.getStringList('my_sharedPreferences_list');

if(myStringList==null ){ 
 print('> EMAIL not found!');
  Navigator.of(context).pushReplacement(MaterialPageRoute(
      builder: (context) => Login()
  ));
}
else { print(myStringList[0].toString()); }

Answer 2

You can check if your list is null or empty using this command myStringList == null || myStringList.isEmptymyStringList == null || myStringList.isEmpty .

|| indicates or operator

Answer 3

You have two way to check null The first likes Yeasin if(myStringList==null ) and the second set default value when you get like this

final myStringList =
    sharedPreferences.getStringList('my_sharedPreferences_list') ?? '';

Then check with empty or not empty

if (myStringList.isEmpty) {}
if (myStringList.isNotEmpty) {}