Thread: Exception problem...plzz help

Here is my code snippet ----->

class A
{
    void disp() throws ArithmeticException
    {
        throw new ArithmeticException();
    }
}
 
class B extends A
{
    public void disp()
    {
        System.out.println("Hello");
    }
}
public class Test 
{
 
    public static void main(String[] args) {
       A a = new B();
       a.disp();
 
   }

Here, @ a.disp(), compilation err : unreported exception, java.lang.Exception, must be caught or declared to be thrown.
Here, I am calling method of Class A which does not throw any exception.
So, why this err??
Plzz plzz help.

Originally Posted by Arati2512

Here, @ a.disp(), compilation err : unreported exception, java.lang.Exception, must be caught or declared to be thrown.
Here, I am calling method of Class A which does not throw any exception.
So, why this err??
Plzz plzz help.

Hello Arati2512!
I tried your code and it runs without any error. Are you sure this is the code that is causing the error?

Oops....My mistake! It should be like this ---->

class A
void disp() throws Exception
{
throw new Exception();
}

As the error message says java.lang.Exception, must be caught or declared to be thrown.
You should either declare it by adding a throws clause in your main like you do in your disp() method or catch it by placing the statement that may cause the exception (here the method call) inside a try...catch block.

ya...but why?
Because it is not necessary. If the base class is throwing exception, then derived class may or may not throw. And I am calling derived class's method on object.

Originally Posted by Arati2512

ya...but why?
Because it is not necessary. If the base class is throwing exception, then derived class may or may not throw. And I am calling derived class's method on object.

I'm not sure what is your exact question. As you said derived class may or may not throw. Therefore because of the *may throw*, main should declare or catch the exception. If you are asking why an exception, must be caught or declared to be thrown I'm not the appropriate to tell you why is this a java requirement, but here is an interesting link.