Dart Custom Exception Class example. Dart tutorial for Flutter. #7.2

[@RajA-me9cl]

Simple and clear. Your tutorials are very helpful. Thank you so much mate. Blessings at you 🙏🏼

[@rashedahmed6339]

Your tutorials are very helpful. You're a legend.

[@gaurav1252]

perfect! bro can u plz make an ebook of dart and flutter... its very helpful to refer stuffs quickly... thanks!:)

[@hicnar]

I think one important concept is missing here. You do not address how to differently handle different types of exceptions in multiple catch blocks corresponding to the same "try" also what happens if the custom exception caught does not implement the errorMessage( ) method as in your example (and if that's the case you will get noSuchMethod exception thrown from within the catch block). try { // code throwing different types of exceptions } on DepositException catch (e) { // a typed exception handled here, safe access to all methods and fields it actually implements/defines without the risk of noSuchMethod being thrown } on SecurityException catch (e) { // another exception type handled here, and similarly access to all methods and fields it actually implements/defines }

[@zeusking4468]

correct !

[@Wongmc644]

great tutorial but doesn't work with latest dart version! I'm learning a lot from this tutorial. i tried and manage to get it working as below codes, sharing & hope it can help others.. ============== void main() { print('case 5'); try { depositMoney(-200); } catch (e) { print(e.toString()); } } class DepositException implements Exception { @override String toString() { //return errorMessage(); return ('you cannot enter amounts < zero'); } // method not needed, return text direct from overridden method toString() // only need to override toString method from super class Exception to //return error text // return ('you cannot enter amount < 0'); // } } void depositMoney(int amount) { if (amount < 0) { throw DepositException(); } } ==============

[@vighneshsharma]

FOR THOSE WHO ARE FACING PROBLEM WIITH NEW DARTPAD SDK You can also implement toString() in the exception so you can call its message with e.toString(). so the code will be void main(){ try{ depositMoney(-200); } catch (e){ print(e.toString()); } } class DepositException implements Exception{ String toString() => "you cannot enter amount less than 0"; } void depositMoney(int amount){ if(amount < 0){ throw DepositException(); } } //goodluck

[@jayednahian1405]

thats nice without using the specific function name ! i came up with a conclusion too !.. try { depositMoney(-200); } catch (e) { print(DepositException().errorMessage()) }

[@labeeb2903]

try{ depositAmount(-100); } on DepositException catch (e){ print(e.errorMessage()); }

[@eainsworld4864]

Thank you so much.

[@gamersguildboxbreaks9063]

I literally don't understand but it worked Pls can I get your Instagram or WhatsApp number so you can explain better to me pls Thanks

[@soonclass4269]

You can also implement toString() in the exception so you can call its message with e.toString() import 'package:flutter/material.dart'; class InternalServerException implements Exception { final String msg; InternalServerException({@required this.msg}); String errorMessage() { return msg; } @override String toString() => msg; }

[@syednokhaizalhassan1800]

class CustomException implements Exception { String cause; CustomException(this.cause); String errorMessage() { return cause; } } void throwException(int amount) { if (amount < 0) { throw new CustomException("The amount less than zero not acceptable"); } } void main() { try { throwException(-200); } on CustomException catch (e) { print(e.errorMessage()); } }

[@rifatmehedi2082]

Sir... Please connect charger with your laptop... only 11% charge available. Thanks for your nice videos anyway:)

[@smartherd]

Haha

[@rahulsrinivas1004]

chutiya

[@saisasisai]

Nice 👌 Tutorial series ...!

[@abhaythakur8572]

you said at 1:15 Exception is a Class in dart if it is a class then you should use extends keyword as i know we use implements keyword with interface please clear my doubt

[@__shubham__]

Sir please help, in new update of Dart SDK V2.12.1 String errorMessage() is impeding the program to run, saying *The body might complete normally, causing 'null' to be returned, but the return type is a potentially non-nullable type. Try adding either a return or a throw statement at the end.* Also it says _The method 'errorMessage' isn't defined for the type 'Object'. Try correcting the name to the name of an existing method, or defining a method named 'errorMessage'_ . Edit : _Actually in new version i.e. V2.12.1 and above , null string is no longer supported_ . you can't do *String* name ; // _initially null_ So now one has to write *String* name = "name"; // _some default name initially that can be renamed later_

[@shreyashkashyap]

Unable to access errorMessage() from main(). It shows - The method 'errorMessage' isn't defined for the type 'Object'. Try correcting the name to the name of an existing method, or defining a method named 'errorMessage'.

[@mayankgarg9728]

yes please tell; and the error is logically right too as without creating an object of class how can you directly call its function?

[@jayednahian1405]

@@mayankgarg9728 i think " throw new DepositException();" line of helps to create the object

[@parikumari7004]

You have solution for this question, i am facing same problem plzz help?

[@subhamkrpaul1034]

Try this code, Happy coding: void main() { try { throwException(-200); } on CustomException catch (e) { print(e.errorMessage()); } } class CustomException implements Exception { String cause; CustomException(this.cause); String errorMessage() { return cause; } } void throwException(int amount) { if (amount < 0) { throw CustomException("The amount less than zero not acceptable"); } }

[@psychopath4351]

thanks bro. you saved my day!

[@ripudhman7355]

Thanks 🙏

[@MohamedDernoun]

hi @Smartherd, is there a way to make a custom Exception where i add only a string -that help to identify the place of exception on the program- to the existing Exception

[@nolssmit]

The example in the video gives errors with Dart version 3+ The new example: void main() { try { depositMoney(-200); } on DepositException catch (e) { print(e.errorMessage()); } } class DepositException implements Exception { String cause; DepositException(this.cause); String errorMessage() { return cause; } } void depositMoney(int amount) { if (amount < 0) { throw new DepositException("The amount less than zero not acceptable"); } }

[@redpersimmon6940]

Thankyou So Much 👍

[@muazbhatti41]

great information in this section.

[@shaaficialli4284]

what is implement idon`t understanding this when you give name class and then class name idon't know where implements and exception comes from please help me

[@AztechZone1]

indeed it is an intersting lecture

[@sushantprajapati1704]

What is the difference in 'throw new' and just using 'throw'? Could you please help me with my confusion!

[@vibhor1386]

what's rethrow?

[@ekshivbhakt2417]

errormessage has no return value, can we use string type if there is no return statement??

[@ziasultan8157]

How do you accessed to depositMoney() from main method Program says depositMoney() is not defined

[@saad-rc8mn]

I am trying a same code but in output show a error why? Error: The method 'errorMessage' isn't defined for the class 'Object'. - 'Object' is from 'dart:core'. Try correcting the name to the name of an existing method, or defining a method named 'errorMessage'. print(e.errorMessage());

[@Anonymous-ig5nm]

Same for me also how to debug it

[@dibyodhara4326]

try { depositMoney(-200); } on DepositException catch(e) { print(e.errorMessage()); }

[@parikumari7004]

@@dibyodhara4326 nice , thanks

[@ritwikrajsingh3420]

Few things are outdated now, please try to fix them, it'll help alot

[@thefossenjoyer3346]

Yeah, this is outdated. Weird how much a language can change in 4 years. xD

[@ritwikrajsingh3420]

@@thefossenjoyer3346 Google is trying to make a mess instead of convenience.

[@thefossenjoyer3346]

@@ritwikrajsingh3420 ah yes.

[@arnabdeb1486]

dartpad shows the method 'errorMessage' isn't defined for the type object

[@dineshbhavsar1435]

Same Daut me

[@georgerassovsky3733]

Had the same problem. This works for me: try { depositMoney(-200); } on DepositException catch (e) { print(e.errorMessage()); }

[@davestr2046]

Perfect!

[@cybernerd7492]

nice vid

[@coffeeCatPeanutDust]

The code in this video unfortunately no longer seems to work

[@raptorrogue4227]

This doesnt work on dartpad 😓

[@bivu8951]

Cant understand -- "implements Exception"

[@smartherd]

Continue watching. U will get to know what it is

[@jesssinues415]

@0:32 Thank me later.

[@md.soleymankhan6550]

Do not know why that code is not running. But this worked: class DepositException implements Exception{ String errorMessage() => "you can not add amount less then 0"; } void main(){ int amount = -200; try { depositMoney(amount); }catch(e){ print(e.errorMessage()); } } void depositMoney(int amount){ if(amount

[@kapilsahu1218]

noob! :p