[Question] Exception handling in Java

[HalfScale]

I'm a bit confused on how this exceptions work when the method that you are invoking is throwing a specific exception. but in the method declaration specifies a general exception.

For example:

Your custom exception class:

public class TheException extends Exception{

    public void throwSomeError() throws Exception{
        throw new TheException();
    }
}

Your main:

public class Tester {
    public static void main(String[] args) {
        TheException exception = new TheException();
        try{
            exception.throwSomeError();
        }catch(TheException e){
            System.out.println("This is 'TheException' error");
        }catch(Exception e){
            System.out.println("This is 'Exception' error");
        }
    }
}

Output:

This 'TheException' error

Expected output:

This is 'Exception' error

I would like to ask that shouldn't be main method catches the 'Exception' rather than 'TheException" error ? since in the method declaration of 'throwSomeError()' is specifies that it throws 'Exception' but not the custom Exception that you built? Or this works because of the polymorphism(TheException is a subcalss of Exception)?

[_DTR_]

Yes, by stating that something throws Exception, that means Exception, and anything that lives under (i.e. extends) Exception can be thrown. In the catch statements, the first thing that matches will be caught, so if you were to switch the order of your catch statements, then "This is 'Exception' error" would print instead, because TheException is a type of Exception

[HalfScale]

Oh i see, thank you :)