query about overridden method

[Jose Coqueiro]

The exam watch on the page 108 says in a nutshell that if the overridding method does not declare a exception that is declared in the overridden method the code will not compile.
but I write similar code, and its working as follow:

public class TesteClass {
	
	public static void main(String [] args)throws Exception {
		Class1 c = new Class2();
		Class2 c2 = new Class2();
		c2.className();
		c.className(); //according to the book this not work
		
	}
}

public class Class1 {

	String s = "Class1";	
	
	public void className() throws Exception {
		try {
			System.out.println("Class1");
		} catch (Exception e) {
			e.printStackTrace();
			throw new Exception();
		}
	}	
}

public class Class2 extends Class1 {
	
	public void className()  {
		System.out.println("Class2");
	}		
}

and the output is :

Class2
Class2

could anyone explain this???

thanks!!!

[Aurelian Tutuianu]

You code seems right to me. I think what you read was that the overriding method should not declare an exception which was not declared before by overridden.

[Cameron Wallace McKenzie]

Indeed. It's the overriding of a method with an exception that can cause the trouble.

-Cameron McKenzie

[Mo Jay]

Sorry Jose Coqueiro but the book is correct and you are wrong.

It looks like you are modifying the code and not following what the exam watch has said exactly, if you look carefully to your main() method it looks like you throws the exception there. So if you remove the Exception in your main() method then the error will be reported by the compiler, that Exception must be caught or thrown again which is what you did exactly therefore you should not have complained why your code works. If you want to test something in the future for confirming a solution, you need to make sure to stick with the conditions.

Cheers!!!

[Jose Coqueiro]

right...one more doubt about it!!!

in the code posted earlier....

when jvm call the line

c.className();

it should not print "Class1" since the method className in the Class2 does not throw the Exception...and the compiler thinks that Im calling the superclass method?

I think there is a difference between compiler vs runtime on this question.

[Lucas Smith]

Compiler doesn;t know which method will be invoked. Compiler can only check if the reference type has the method.
In this case we talk about late binding.