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.