this error is in udemy maximilian schwarzmuller's flutter course error. this is the code: I have provided the string value still I getting nonnull string provided to text widget error in ('tx.title'),

import 'package:flutter/material.dart';
import './transaction.dart';

void main() => runApp(MyWidget());

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'flutter app',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  final List<Transaction> transactions = [
    Transaction(
      id: '01',
      title: 'azeem',
      amount: 90.98,
      date: DateTime.now(),
    ),
    Transaction(
      id: '02',
      title: 'azeem',
      amount: 90.98,
      date: DateTime.now(),
    )
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Expense App'),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.spaceAround,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          Container(
            width: double.infinity,
            child: Card(
              child: Text('Text_1'),
              color: Colors.blue,
            ),
          ),
          Column(
            children: transactions.map((tx) {
              return Card(
                child: Text(tx.title),
              );
            }).toList(),
          ),
        ],
      ),
    );
  }
}

I have provided the string to this function but I am getting an error.

enter image description here

CodePudding user response：

try this;

  Column(
        children: transactions.map((tx) {
          return Card(
            child: Text(tx.title ?? "default text on null"),
          );
        }).toList(),
      ),

CodePudding user response：

You have multiple ways to solve this problem

1.

Column(
        children: transactions.map((tx) {
          return Card(
            child: Text(tx.title!= null ? tx.title : "Default Title"),
          );
        }).toList(),
      ),

2.

Column(
        children: transactions.map((tx) {
          return Card(
            child: Text(tx.title ?? "Default Title"),
          );
        }).toList(),
      ),

3.

if(tx.title != null)
Column(
        children: transactions.map((tx) {
          return Card(
            child: Text(tx.title!),
          );
        }).toList(),
      ),

4.

Column(
        children: transactions.map((tx) {
          return Card(
            child: Text(tx.title.toString()),
          );
        }).toList(),
      ),