programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
• Campbell Ritchie
• Paul Clapham
• Ron McLeod
• Tim Cooke
• Junilu Lacar
Sheriffs:
• Rob Spoor
• Devaka Cooray
• Jeanne Boyarsky
Saloon Keepers:
• Jesse Silverman
• Stephan van Hulst
• Tim Moores
• Carey Brown
• Tim Holloway
Bartenders:
• Jj Roberts
• Al Hobbs
• Piet Souris

# MultiDimensional Arrays

Ranch Hand
Posts: 37
• Number of slices to send:
Optional 'thank-you' note:
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
}}

Line 3 outputs null which is fine,because arrays declared within the method are initialised to null..

Could any body tell me why line number 8 throws up null pointer exception?

Greenhorn
Posts: 10
• Number of slices to send:
Optional 'thank-you' note:
Hi all
a3[0] = a3[1] = a3[2] = a2;
now a3[2] is not a 2*2 array ( 2 rows and 2 columns)
it just 1*2 array
u r trying to retrive a3[2][2][2]
a3[2][x][y] is nothing but a2[x][y]
a3[2][2][y] is nothing but a2[2][y]

but a2 dose not have 2 nd row since it is having 0th row and 1th row (array index starts at 0)
correct me if iam wrong
thank you

 Don't get me started about those stupid light bulbs.