• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Tim Cooke
  • paul wheaton
  • Paul Clapham
  • Ron McLeod
Sheriffs:
  • Jeanne Boyarsky
  • Liutauras Vilda
Saloon Keepers:
  • Tim Holloway
  • Carey Brown
  • Roland Mueller
  • Piet Souris
Bartenders:

Broader exceptions thrown by methods that implement interfaces

 
Ranch Hand
Posts: 434
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Question from Enthuware

Consider these two interfaces:

interface I1
{
void m1() throws IOException;
}
interface I2
{
void m1() throws SQLException;
}

What methods have to be implemented by a class that says it implements I1 and I2 ?



I selected

public void m1() throws Exception

which is wrong

Is this because m1() is throwing a broader Exception?

Then please explain why the class that implements interface I1 and I2 can throw Exception. Please see Enthuware's explanation below:

When interfaces are involved, more than one method declaration may be implemented by a single method declaration. In this case, the overriding declaration must have a throws clause that is compatible with ALL the overridden declarations. The declaration public void m1(){} satisfies both the declarations. Example...






 
Sheriff
Posts: 9709
43
Android Google Web Toolkit Hibernate IntelliJ IDE Spring Java
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Then please explain why the class that implements interface I1 and I2 can throw Exception.


A class never throws an exception, methods do. In the code the overriding m1 method is actually not throwing any exception. Thats the point. The reason for throwing Exception from the main method is completely different and has nothing to do with TestClass implementing I1 and I2...
 
Ranch Hand
Posts: 2066
IntelliJ IDE Clojure Linux
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Sandra Bachan wrote:
Is this because m1() is throwing a broader Exception?


Yes, and you are mixing two different things here. Declaring the main() method as it throws Exception and overriding the method m1() are two different things!
 
Abimaran Kugathasan
Ranch Hand
Posts: 2066
IntelliJ IDE Clojure Linux
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Oh, Ankit answered!
 
Sandra Bachan
Ranch Hand
Posts: 434
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Thank you
 
reply
    Bookmark Topic Watch Topic
  • New Topic