initializing multidimensional array

[Vaibhav Chauhan]

Read the following code where I have created a multidimensional array of references in which I have not instantiated(commented in the code) the second dimension of array:

 
public class ArrayOfReferences {
 
public static void main(String[] args)
{
ArrayOfReferences[][] aor=new ArrayOfReferences[5][];
//aor[0]=new ArrayOfReferences[2];           //line 1

System.out.println("ArrayOfReferences[0]: "+aor[0][0]);
}
}

here compiler doesn't have any problem but there is runtime exception. My question is that why compiler doesn't complain that we can't use aor[0][0] before instantiating because after instantiating only reference starts pointing null(i.e. at line 1).
[ August 30, 2006: Message edited by: Vaibhav Chauhan ]

[Vaibhav Chauhan]

   
public static void main(String[] args){
 String s;
 s.toUpperCase();
}

this code generates compilation error that local variable is not initialised. How the above case is different from this one.
[ August 30, 2006: Message edited by: Vaibhav Chauhan ]

[Balasubramani Dharmalingam]

The elements of the array will be initialized to its default values 0 for primitives , null for Objects ..

   
String[] strArray = new String[3] ;
System.out.println( strArray[0] ) ; // Prints null
 

Here all the string references are initialized to its default values.Like this
in

ArrayOfReferences[][] aor=new ArrayOfReferences[5][];
 

aor[0],aor[1]... aor[4] will be initialized to null, when you access anything using null reference NullPointerException will be thrown.