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Declaring a 2D array

Charles Mara
Greenhorn

Joined: Dec 17, 2011
Posts: 3
Hi All,

I know you can declare a 1D array this way


is there a away to do this for a 2D array?
Charles Mara
Greenhorn

Joined: Dec 17, 2011
Posts: 3
nevermind a deeper google got me the answer
fred rosenberger
lowercase baba
Bartender

Joined: Oct 02, 2003
Posts: 11351
    
  16

So you found you can't create a 2-D array in java, just plain old 1-D ones that can hold anything...including arrays?


There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 39044
    
  23
Actually your original code has some poor style. You should but the [] earlier.
Needless to say, this sort of question comes up frequently, and here is some good discussion of it. But as Fred has already hinted, you are not creating a 2D array.
Charles Mara
Greenhorn

Joined: Dec 17, 2011
Posts: 3
Thanks for the replys.

So I should declare arrays this way

is that right?

and no I didnt relise that arrays could hold other arrays but I do now!Will look in to it further just to make sure I have the understanding of them correct.
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 39044
    
  23
Yes, you should declare arrays like that, [] before the name of the array. That is because the variable is of type something-array, so you declare the type as something-array, then the name.
int[][] arr is not a 2D array, but a 1D array containing however many 1D arrays. Or more precisely, enough memory put aside to contain that in the reference. arr[123] is a 1D array, provided arr has been instantiated with enough elements to support an index of 123.
 
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