Java Interview Questions

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Answered by: sivagopal

View all answers by sivagopal

Member Since Jun-2009 | Answered On : Jun 8th, 2009

A variable that won't be allowed for object serialisation. so that the state of the value will always be defaulted after the deserialisation.
For example a variable x's value is set to 9, it's default value is '0' say, when the object has been serialized having x's value 9, after deserialisation will be defaulted to '0'

Use: In Java, serialization of an object allowed only when all the underlying objects of the object that is currently under serialization contains has a relationship, will not be allowed, some times the developer has no choice of implementing serializable marker interface on some classes as the classes might have been arrived from a third party and the developer has no control over them, but the developer needs to serialize the object's state, then the developer has the choice of marking the objects that not serializable as transient.

Editorial / Best Answer

Answered by: sri

throw is used to throw an exception manually, where as throws is used in the case of checked exceptions, to reintimate the compiler that we have handled the exception. so throws is to be used at the time of defining a method and also at the time of calling that function, which rises an checked exception.

Prog. to explain diff. b/w  throw and throw:

class MyException extends Exception //to create our own exception
{
public String toString()   //overriding the method toString() to print the desired msg.
{
return "Can not divide a no. with one: "+"MyException";
}
public static void main(String args[]) throws MyException //use of throws
{
int a=Integer.parseInt(args[0]);
int b=Integer.parseInt(args[1]);
if(b==1)
throw new MyException();  // rises an MyException, if we try to divide a no. with 1
else
System.out.println((float)a/b);
}
}

if we want to rise our own exception, we have to use either throws or to handle the exception by try-catch. if not, it gives the compile time error.

and throw is to rise the exception manually, In the above prog. I rised an exception when you try to divide a no with 1.(own Exception)

     ----sri