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Q) Example program an user defined exception implementation?

Q) Example program an user defined exception implementation?
A)


class votingException extends Exception
{
      
}//user defined, checked Exception

class voting
{
       public static void isEligibletovote(int age) throws votingException
       {
              if (age<19)
                     throw new votingException();
              System.out.println("can cast vote");
       }
}
class votingapplication {
public static void main(String[] args) {
       try
       {
              int age=Integer.parseInt(args[0]);
              voting.isEligibletovote(age);
       }
       catch(Exception e)
       {
              System.out.println(e);
              if(e instanceof votingException)
                     System.out.println("invalidage. can't vote");
              if( e instanceofNumberFormatException)
                     System.out.println("please supply again digits only");
       }
/*only one catch block. It is not advisable because more no.of conditions reduces the performance.*/

 /*catch(votingException e)
  {
    e.printStackTrace();
    System.out.println("invalid age. can't vote");
  }
  catch(NumberFromatException e)
  {
    System.out.pritnln(e.getMessage());
    System.out.println("please supply age in digits only");
 }*/
}
}

Output:
java.lang.ArrayIndexOutOfBoundsException: 0

Note:
->Whenever multiple exceptions i.e. more than one kind of exception raising chance is there in try block, to handle each exception specifically, we go for multiple catch blocks.
->even though multiple catch blocks are implemented, only one catch block is executed.
->when we specify multiple catch blocks, super class executed catch blocks should not precedence the sub class exception catch block.

Unreadable code is a syntactical error in java”

Ex:
try
{ }
catch(Exception e)
{ }
catch(NumberFormateException e)
{ }

->Here syntactical exception is raised. The super class exception(i.e. Exception) is precedence to the its child class exception (i.e. NumberFormateException).

try
{ }
catch(NumberFormateException e)
{ }
catch (Exception e)
{ }

->Here error is not raised.

Additional information:
->getMe() it returns a string not location information.                                                                                                                                                                                                                                                
It returns the error description but not returns where it is raised. i.e. line number (it is location information).
->1) type of exception
    2) Error description
    3) Location is also displayed with e.printStackTrace()
->when directly priting the exception reference i.e. when we display System.out.println(e);
Then it display:
Type of exception
Error description, but it not displays location of exception.

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