Exception handling with respect to overriding

Question

If SuperClass declares an exception, then the SubClass can only declare the child exceptions of the exception declared by the SuperClass, but not any other exception, what if I'm declaring checked exception in parent method?

what if I'm declaring checked exception in parent method?

class SuperClass6 { 
// SuperClass doesn't declare any exception 
    void method()throws IOException 
    { 
        System.out.println("SuperClass"); 
    } 
} 

// SuperClass inherited by the SubClass 

class SubClass6 extends SuperClass { 

// method() declaring Unchecked Exception ArithmeticException 


    void method() throws FileNotFoundException
    { 

        // ArithmeticException is of type Unchecked Exception 
        // so the compiler won't give any error 

        System.out.println("SubClass"); 
    } 

    // Driver code 
    public static void main(String args[]) 
    { 
        SuperClass s = new SubClass(); 
        s.method(); 
    } 
 }

Possible duplicate of [this](https://stackoverflow.com/questions/5875414/why-cant-overriding-methods-throw-exceptions-broader-than-the-overridden-method) — ghoul932, Mar 30 '19 at 07:47
Possible duplicate of [Why can't overriding methods throw exceptions broader than the overridden method?](https://stackoverflow.com/questions/5875414/why-cant-overriding-methods-throw-exceptions-broader-than-the-overridden-method) — Progman, Mar 30 '19 at 09:33

score 1 · Accepted Answer · answered Mar 30 '19 at 08:09

If you declared a checked exception in parent class method (or an interface) all of the descendents can

declare the same exception
declare any sub-class of this exception
don't declare any exceptions

So, subclasses can't have a broader throws policy, because the calling code may use your objects through parent abstraction and they would be unaware of those.

As to the unchecked exceptions they are basically unregulated at compile time. You are allowed to declare them in throws block as much as you like or throw them without explicit declaration and the calling (or driver as you called it) code will never be forced to handle them.

You can read up more on this Java: checked vs unchecked exception explanation, Why can't overriding methods throw exceptions broader than the overridden method?

but it is not allowing me to declare its child exception in overridden method. — Rohit Karambali, Apr 04 '19 at 10:45
@RohitKarambali The code that you provided in question should compile — Nestor Sokil, Apr 04 '19 at 10:51

Exception handling with respect to overriding

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