Answers for "Unhandled Exception"

unhandled exception: type

It means a method you're calling is declared with the throws directive for an exception derived from the Exception class. When a method is declared in this way, you are forced to deal with the exception using a try/catch block or add an identical throws (for the same exception or a super type) statement to your method declaration.

An example.

I want to call some method foo inside my method bar.

Here is foo's definition:

public static void foo(String a) throws Exception {
    // foo does something interesting here.
}
I want to call foo. If I simply do this:

private void bar() {
    foo("test");
}
...then I'll get the error you are experiencing. foo declares to the world that it really might decide to throw an Exception and you had better be ready to deal with it.

I have two options. I can change bar's definition as follows:

private void bar() throws Exception {
    foo("test");
}
Now I've publicized my own warning that my method or some method I call could throw an Exception that the user of my method should deal with. Since I've deferred responsibility to my method's caller, my method doesn't have to deal with the exception itself.

It's often better to deal with the exception yourself, if you can. That brings us to the second option, the try/catch:

private void bar() {
    try {
        foo("test");
    } catch(Exception e) {
        Log.wtf("MyApp", "Something went wrong with foo!", e);
    }
}
Now I've dealt with the potential Exception thrown by foo that the compiler was complaining about. Since it's been dealt with, I don't need to add a throws directive to my bar method.

Unchecked exception

All subclasses of RuntimeException are called unchecked exceptions. 
These are unchecked exceptions because compiler does not checks if a method 
handles or throws exceptions. Program compiles even if we do not catch the 
exception or throws the exception. If an exception occurs in the program,
program terminates. It is difficult to handle these exceptions
because there may be many places causing exceptions.
Example : 
1) Arithmetic Exception
2) ArrayIndexOutOfBoundsException
3) ClassCastException
4) IndexOutOfBoundException
5) NullPointerException
6) NumberFormatException
7) StringIndexOutOfBounds
8) UnsupportedOperationException

flutter unhandled exception

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

void main() =>
  runZoned<Future<void>>(
    () async {
      runApp(MyApp());
    },
    onError: (dynamic error, StackTrace stackTrace) {
      print("=================== CAUGHT DART ERROR");
      // Send report
      // NEVER REACHES HERE - WHY?
    },
  );

class MyApp extends StatefulWidget {
  // This widget is the root of your application.
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {

  @override
  void initState() {
    super.initState();

    // This captures errors reported by the FLUTTER framework.
    FlutterError.onError = (FlutterErrorDetails details) {
      print("=================== CAUGHT FLUTTER ERROR");
      // Send report
      // NEVER REACHES HERE - WHY?
    };
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: SafeArea(
          child: RaisedButton(
            child: Text("Throw exception"),
            onPressed: () {
              throw Exception("This is a test exception");
            },
          ),
        ),
      ),
    );
  }
}

c# unhandled exception in thread

Console.WriteLine("Your Gay");