Exception?

[harsh anajwala]

14. int[] x=new int[2];
15. try{
16. x[2]=x[1]/0;
17. }catch(NullPointerException e){
18. System.out.print("NPE ");
19. }catch(ArithmeticException e){
20. System.out.print("AE ");
21. }catch(ArrayIndexOutOfBoundsException e){
22. System.out.print("AIOOB ");
23. }



what is output??
The question is from ExamLab.....

[Ulf Dittmer]

What happened when you tried it?

[harsh anajwala]

according to ExamLab it's Arithmatic Exception bt dnt you thnk that it shud be NullPointer EXc...??

[Ankit Garg]

Harsh please Use Real Words on javaranch.

Why do you think there will be NullPointerException?? The array is of primitive type int, so the elements in the array will be initialized with the default value i.e. 0. If it was an array of references, then there was a chance of NullPointerException as the elements of an array of references is by default initialized with null...

[Devaka Cooray]

harsh anajwala wrote:according to ExamLab...

You *must* try the code yourself, instead of relying on other references.

[S Ali]

Isn't this a question about operator precedence because in the book K&B they say we are not required to know them.

[Devaka Cooray]

Nothing to do with operator precedence here. But you need to know the procedure of assigning a value to a variable (or an array element).

[indra negi]

I tried this code and it is AE.

I want to ask one thing that the array has been created with two elements and they should be x[0] and x[1].

Why the compiler doesnot complain when I try to assign something to an array element which is out of the bounds of that array and if the compiler doesnot do that then ArrayIndexOutOfBoundsException should be thrown.

I don't know whether I am able to ask my doubt or not but please answer it.

[Vijitha Kumara]

indra negi wrote:Why the compiler doesnot complain when I try to assign something to an array element which is out of the bounds of that array and if the compiler doesnot do that then ArrayIndexOutOfBoundsException should be thrown.

What is the output of RHS in the code ?

x[2]= x[1]/0; 

[indra negi]

It will result in ArithmeticException.

[Prithvi Sehgal]

I believe, you are asking when you are writing a code something like this

    

int[] x = new int[2];

x[3] = 5;

You must be trying something like that. Actually when we are talking about the statement like new int[2], it is basically making an array object on
the heap. The object creation will happen at run-time. Right now, the compiler is aware that, it is an int type array, it allocates the size at run-time
to my information. That's why right now the compiler won't know that you are accessing something out of the bounds of array. It will only be caught
by the JVM at run-time

Hope this helps,

[indra negi]

Ok then it should throw exception at runtime as the array element is not within the bounds.

[Prithvi Sehgal]

Yes surely it does/

[harsh anajwala]

And just to add something....

When an assignment statement is encountered ,first right side is exectued so in this case it will throw Arithmatic Exception so then after there is no chance for ArrayindexoutofBound Exception....

and if the Array is of objects than there should be NullPointerException...what say??!!

[Dhruv Arya]

Harsh is correct in saying that the expressions are evaluated from right to left in assignement.
An ArrayIndexOutOfBoundsException will be thrown if the expression is replaced with

 x[1] = x[2]; 

[indra negi]

Got it. Thanks to all.

[Prithvi Sehgal]

You correctly stated it harsh. Thats right in assignment, it will be evaluated from right to left.

Cheers,