comparing an object with null

Re: comparing an object with null


"Asad Khan" <uoft_cstutor@y ahoo.com> wrote in message
news:zZvob.1311 73$h61.37249@ne ws01.bloor.is.n et.cable.rogers .com...[color=blue]
> I have the following method in a class 'foo'.
>
> public boolean equals(Object o) {
> if (!(o.equals(nul l))) {
> // do some stuff
> }
> }
>
> The problem I am having is that, if the object that is passed in is
> instanceof foo, then it recursively calls the equals method, and I get a
> nullpointer exception. So how can I compare if the object that is being
> passed in is null or not?[/color]

Remember, objects are not passed, object references are passed.

-- glen

Re: comparing an object with null

"Asad Khan" <uoft_cstutor@y ahoo.com> wrote in message news:<zZvob.131 173$h61.37249@n ews01.bloor.is. net.cable.roger s.com>...[color=blue]
> I have the following method in a class 'foo'.
>
> public boolean equals(Object o) {
> if (!(o.equals(nul l))) {
> // do some stuff
> }
> }
>
> The problem I am having is that, if the object that is passed in is
> instanceof foo, then it recursively calls the equals method, and I get a
> nullpointer exception. So how can I compare if the object that is being
> passed in is null or not?
>
> Thanks.[/color]
public boolean equals(Object o) {
if (!(o == null)){ //null is not an Object, that is 'none-object'
place holder refrence ... sole pointer in Java!
// do some stuff
}
else[
return false;
}
}