WebThe method firstWhere () iterates through the list and returns the first item to satisfy the given condition. The orElse () method is invoked if no element satisfies the condition. … WebFeb 2, 2024 · how can i return String value from list by it's name value in dart list. List books = ['book1', book2] String getTextWidget () { return // here i need to only return the element which is 'book1' such as if books.contains ('book1') return this element as String ; } i tried the following code , it is work but it does not accept String Widget.

Unhandled Exception: Bad state: No element #47040 - GitHub

Web您不能返回null，因为预计该方法将返回City类的实例，该实例不是nullable。. 你有两个解决方案： 您可以将_cities列表声明为List (可空城市列表)。 然后，方法firstWhere … WebOct 11, 2024 · Refactoring the finder logic into a helper method. Since the task of finding an element by id in a list of objects is quite a common one, I like to extract that logic into helpers file, for example: class Helpers { static findById (list, String id) { var findById = (obj) => obj.id == id; var result = list.where (findById); return result.length ... data link feature exchange enable or disable

How to find an element in a dart list - Stack Overflow

WebOct 13, 2024 · If orElse not defined in the code and the wrong item gets search which doesn't exist in the list then it shows BadStateException void main () { List list = ['red', 'yellow', 'pink', 'blue']; var newList = list.firstWhere ( (element) => element.contains ('green')); print (newList); } Output: Uncaught Error: Bad state: No element WebOct 21, 2014 · List myList = String result = myList.firstWhere ( (o) => o.startsWith ('foo'), (o) => null); But the compiler has an error of 1 positional arguments expected, but … WebCreate a grid list. Create a horizontal list. Create lists with different types of items. Place a floating app bar above a list. Use lists. Work with long lists. data linking in cyber security