Exception Handling with then (catchError)
void main() {
//Exception Handling
print(" Start fetching images");
getData().then((images) {
return images + " " + "caption";
}).then((captionedimages) {
print(captionedimages + " " + " save to disk");
}).catchError((err){
// Logic for handling error
print("Error : $err , Sorry for the error , check if you are connected to internet");
});
print("Loading Images");
}
Future<String> getData() {
Future<String> a = Future<String>.delayed(Duration(seconds: 5), () {
// Logic
print(" Image Fetched !!!!!");
throw "404 Error";
});
return a;
}
If you want to read more about error handling , here is the official documentation
Exception Handling with async await( try catch block)
void main() async {
// Hadling exception
try{
var images = await fetchImage();
print(images);
var capImages = await captionImages(images);
print(capImages);
var saved = await savetodisk(capImages);
print(saved);
}
catch(err){
// logic for handling error
print("Error $err , check if you are connected to internet");
}
}
Future<String> fetchImage() async {
await Future<String>.delayed(const Duration(seconds: 5));
throw "500 error";
}
Future<String> captionImages(images) async {
await Future<String>.delayed(const Duration(seconds: 5));
return images+" "+"caption";
}
Future<String> savetodisk(capImages) async {
await Future<String>.delayed(const Duration(seconds: 5));
return capImages+" "+"Saved";
}
You should go through the following codelab to get a better understanding of asynchronous programming in dart :-
