throws

[Syamsul Hussin]

hi, i dont understand about the throws modifier. for example, why do i have to throw java.lang.InterruptedException if i want to use thread in the method body?, why cant i use try and catch statement before i use thread in my code and try to catch the exception instead? can a method throw more than one exception? thanks

[karl koch]

hi

yes, a method can throw more than one Exceptions:

  
public void someMethod() throws ExceptionA, ExceptionB, ExceptionC.....

you dont need to declare the Exception if you catch it:

  
public void someOtherMethod() throws ExceptionC {
  try {
    // call a method that throws Exceptions
    // see code snipet above.
    // well catch the A and B Exception
    // so no need to declare them in the "throws"
    // part.
    someMethod();
  } catch(ExceptionA a) {
    // Exception handling for this Exception
  } catch(ExceptionB b) {
    // Exception handling for this Exception
  }
}

if you use

 
try {
  // something that throws exceptions
} catch(Exception e) {
}
 

then you catch all subclasses of Exception.

k

[J.H.B. Oosterlaar]

Originally posted by Syamsul Hussin:
hi, i dont understand about the throws modifier. for example, why do i have to throw java.lang.InterruptedException if i want to use thread in the method body?, why cant i use try and catch statement before i use thread in my code and try to catch the exception instead?

You don't have to throw the InterruptedException, you can simply catch it within the method. I don't know what makes you believe otherwise. For example:

public void tick()
{
     try
     {
          Thread.sleep(100);
          System.out.println("tick");
     }
     catch(InterruptedException ie)
     {
          System.err.println("tick error");
     }
}

Jeroen Oosterlaar

[Syamsul Hussin]

Hi, if I declare a class to extend a super which throws an exception, do I have to throw the same exception again? thanks