Adding null to Long

[Sharon whipple]

In Car Class, I have plate Number (Long)
when I increment it I do :

car.setPlateNumber(car.getPlateNumber()+1L);

what will happen if the PlateNumber is null?
isn't it like null + Long?

[Paul Sturrock]

I got a NullPointerException when I tried it. What heppened when you tried it?

When you do this:

Long one = new Long(1);
Long two = new Long(2);
 
Long result = one + two;

remember that autounboxing is happening in the background. So effectively what you are doing (pre JDK 1.5) is:

Long one = new Long(1);
Long two = new Long(2);
 
Long result = new Long(one.longValue() + two.longValue());

One of the reasons (in my opinion) autoboxing is best avoided.
[ June 18, 2008: Message edited by: Paul Sturrock ]

[Rajkamal Pillai]

Hi Sharon,

A NullPointerException will be thrown cause you are trying to add a value to 'null'. Never had considered a situation this kinds so I tried it out and thats what happened for me.

Cheers,
Raj.

[Gopikrishna Kunisetty]

Hi Sharon,

If you have declared the data type of Plate number as long, then obviously its initial value will be '0' and not 'null'. So, if you try to increment, it will run without any issues.

[Sharon whipple]

I have to Use Long in order to identify null values,
Well i guess the answer is

if(car.getPlateNumber()==null)
  car.setPlateNumber(0L);
 
car.setPlateNumber(car.getPlateNumber()+1L);