Can't errors related with instantiating / inheriting class be treated by try~catch statement?

Question

I hope to run the below C# codes to practice usage of abstract / sealed classes :

using System;

abstract class Person
// abstract : can be inherited but can't be instantiated
{
    public Person()
    {
        Console.Write(this + " : ");
    }
}

sealed class MichaelJackson : Person
// sealed : can't be inherited but can be instantiated
{
    public void Say()
    {
        Console.WriteLine("Billie Jean is not my lover.");
    }
}

class BilleJean : MichaelJackson
// An error will occurs because it tries to inherit a sealed class
{
    public void Say()
    {
        Console.WriteLine("You are the one.");
    }
}


class MainClass
{
    static void Main(string[] args)
    {
        
        try
        {
            new Person();
            // An error will occurs because it tries to be instantiated as an abstract class
        }
        catch (Exception e)
        {
            Console.WriteLine("Abstract class can't be instantiated.");
        }

        new MichaelJackson().Say();

        try
        {
            new BilleJean().Say();
        }
        catch (Exception e)
        {
            Console.WriteLine("MichaelJackson : The kid is not my son");
        }
    }
}

As you know, the abstract class Person can't be instantiated directly and also the sealed class MichaelJackson can't be inherited by the other class BillieJean.

I mean to get the result like the following, but the codes don't run although I've added try~catch statement.

Abstract class can't be instantiated.
MichaelJackson : Billie Jean is not my lover.
MichaelJackson : The kid is not my son.

How can I solve this problem?

[Difference between compile time and runtime](https://stackoverflow.com/questions/846103/runtime-vs-compile-time#:~:text=Compile%20time%20errors%20are%20those,or%20features%20don't%20work.) — John Wu, Feb 18 '21 at 18:57

Olivier Jacot-Descombes · Accepted Answer · 2021-02-18T18:59:55.520

You are confusing compiling errors and runtime exceptions.

Trying to inherit a sealed class will produce a compiling error. This means that no executable will be created and that you will not be able to run your code.

A try-catch statement catches exceptions at runtime. E.g., it may catch a "division by 0" exception, but it can not catch a syntax error or a logical error the compiler is complaining about.

The term “runtime” refers to when the code is running. It means that the compiler successfully created an executable file and that you could start it. The compiler can compile successfully when there are warnings (green squiggly lines), code issues or hints (blue squiggly lines), but not when there are errors (red squiggly lines).

I've realized what I was confused exactly. Maybe it was strange to me because I was familiar with script languages, not with compile languages. This trial leads me to understand compile language well. Thank you for your answer! — Kimpro, Feb 19 '21 at 13:00

score 0 · Answer 2 · answered Feb 18 '21 at 18:47

0

The try-catch block only captures run time errors, a.k.a exceptions. What you are getting must be a compile-time error if I am not wrong. Can you verify? Also, your IDE should be displaying an error.

answered Feb 18 '21 at 18:47

stephjoe

1
3

Can't errors related with instantiating / inheriting class be treated by try~catch statement?

2 Answers2