19-02-25
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Q)Explain about "throw" keyword.
=>"throw" is one of the keywords of Java's exception handling mechanism.
=>"throw" keyword is not used to create a block of code unlike try&catch
=>"throw" keyword is used to raise the exception explicitly in the application
by the programmer.
 
            For eg.
	                 throw   new AccountNotFoundException();
                                     
				        OR

                         AccountNotFoundException ae=new AccountNotFoundException();
			 throw ae;

Note:- Exception object has to be created in order to throw it.

Q)What do you know about rethrowing of an exception?
    =>Throwing an exception from within the catch block is nothing but
    rethrowing of an exception.
           For eg.
	               catch(Exception e){
		          throw e;//retrhowing of an exception
		       }

  =>To propogate an exception from one partition(layer) of the project to the
  other partition, the concept of exception rethrowing is used.

Q)Explain about "finally" in the context of exception handling.
=>"finally" is one of the keywords of Java's  exception handling mechanism.
=>"finally" keyword is used to create a block of code.
=>Nature of finally block is that it gets excuted in exception raising case as well
as non raising case.
=>resources releasing code is placed in finally block.
             For eg.   file closing
	                  database connection closing

=>Generally, after the catch blocks finally block is written.
try
{
    .......
}
catch(Exception e)
{
   ......
}
finally
{
   //resources releasing
}
=>try block can be followed by finally block also

try
{
   ........
}
finally
{
   ......
}

Q)Explain about "throws" keyword. 
 =>"throws" is one of the keywords of  Java's exception handling mechanism.
=>"throws" is not used to throw the exception explicitly unlike "throw" keyword.
=>"throws" is not used to create a block unlike try,catch,finally
=>"throws" keyword is used to create "an exception specification" (throws clause)
of a method.
=>We can specify multiple exceptions also in throws clause.  

   For eg.
               public void withdraw() throws AccountNotFoundException,InsufficientFundsException{
                    
	       }
  =>"exception specification" of a method announces to the calling methods
  that this method has risky code in it but not handled. It is the responsibility of
  the calling methods to handle those announced exceptions. 

  =>"throws" keyword purpose is to pass on exception handling duty from
  one method to the other.