help

[Jaffery Rab]

class hey{

String s;
hey(){
if(s.length()==0){
System.out.println("Hello");}
else{
System.out.println("Fail");}

}
public static void main(String args[]){
new hey();
}}
when I compile it, I will get NullPointException even if I will check s.length()<0; or s.length()>0;
why is that?
Jaffery

[Steven Wong]

Hi,
That's because your string variable was not explicitly initialized by you, thus it will be implicitly initialized to null.
Clement

[Manish Hatwalne]

In other words change your if condition to this -

if(s != null && s.length()==0)
{
   System.out.println("Hello");}
}

Due to short circuit nature of && operator, the condition s.length()==0 will be evaluated only when s is not null.
HTH,
- Manish

[Thomas Paul]

Originally posted by Jaffery Rab:
when I compile it, I will get NullPointException even if I will check s.length()<0; or s.length()>0;
why is that?
Jaffery

In fact, the s.length() will cause a NullPointerException because you are running a method on a null!

[Jaffery Rab]

Thanx much guys
Jaffery

[Jessica Sant]

Jaffery-
Just a suggestion -- but try giving your posts a descriptive subject instead of "help" give it something like "NullPointerException with String.length()" -- Just an idea

[Corey McGlone]

Originally posted by Jessica Sant:
Jaffery-
Just a suggestion -- but try giving your posts a descriptive subject instead of "help" give it something like "NullPointerException with String.length()" -- Just an idea

To go along with what Jessica said - giving your posts a good topic makes them easier to search for. If someone wanted to find something on a NullPointerException, they might never find your thread.
Corey