FormatException: Invalid number

Why This Happens

In Dart, int.parse() and double.parse() throw FormatException when the input string is not a valid number. This commonly happens with user input or API data that contains unexpected characters. Use tryParse() for safe parsing that returns null instead of throwing.

The Problem

final input = 'abc';
final number = int.parse(input); // FormatException!

The Fix

final input = 'abc';
final number = int.tryParse(input) ?? 0;

Step-by-Step Fix

1. 1

   Identify the error

   Look at the FormatException message to see which string value could not be parsed as a number.

2. 2

   Find the cause

   Check where you parse user input or API data as numbers without validation.

3. 3

   Apply the fix

   Use int.tryParse() or double.tryParse() which return null on invalid input, and provide a default value.