arrays: IndexOutOfBounds exception

[Varsha Patil]

Hi,

The following code is from Dan Chisholm's site

class A13 {}
class A14 {
  public static void main(String[] arg) {
A13[]     a1 = new A13[1];         // 1
A13[][]   a2 = new A13[2][1];      // 2
A13[][][] a3 = new A13[3][3][3];   // 3
System.out.print(a3[2][2][2]);     // 4
a1[0] = new A13();                 // 5
a2[0] = a2[1] = a1;                // 6
a3[0] = a3[1] = a3[2] = a2;        // 7
System.out.print(a3[2][2][2]);     // 8
}
}
 

When I compiled and ran this program, the output was

nullException in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2
at A14.main(A14.java:11)

I'm not able to understand why we are getting ArrayIndexOutOfBoundsException
Can someone please explain

Thanks,
Varsha

[fred rosenberger]

a3[2] points to a2.

a2[2] points to a1.

a1 only has one element.

so, a3[2][2] points to a1, which has one element, and then you try to access it's second element.