As a good programmer, you test your app in all possible conditions. Dart defines a number of errors for those things that you should remedy in your code, such as
CastError when a cast fails, or
NoSuchMethodError when the class of the object on which the method is called does not have this method, and neither do any of its parent classes. All these are subclasses of the
Error class, and you should code so that they do not occur. But when something unexpected occurs while running the app, and the code cannot cope with it, an
Unhandled Exception occurs. Especially input values that are read in from the keyboard, a file, or a network connection can be dangerous. Suppose input is such a value that is supposed ...