Java: length of multidimensional arrays

Question

I'm using Eclipse Luna and i think it's kind of buggy because when i write:

int[][][] a = new int[2][3][4];
System.out.println(a.length+" "+a[0].length+" "+a[1].length);

Eclipse shows me:

2 3 3

but if i use:

int[][][] a = new int[2][3][4];
System.out.println(a.length+" "+a[0].length+" "+a[0][0].length);

Eclipse shows me:

2 3 4

I don't understand why but because of this reason my whole project doesn't work anymore...

What do you expect for the lengths of a[0] and a[1]? Should they be different? — Code-Apprentice
– Code-Apprentice, Commented Oct 4, 2014 at 19:04
i used goodle to find out how to find the lengths of multidimensional arrays and they've shown me these technics: a[0].length, a[1].length, a[2].length, ... — Tien Do Nam
– Tien Do Nam, Commented Oct 4, 2014 at 19:06
In a 2D array a[0] and a[1] refer to a row in the array. Typically, they should be the same length. This equally applies to a 3D array (although I would hesitate to call this a "row"). — Code-Apprentice
– Code-Apprentice, Commented Oct 4, 2014 at 19:08
@TienDoNam : that would be for the case when the rows have different sizes but the way you declared the array, they all have the same size — Dici
– Dici, Commented Oct 4, 2014 at 19:08
Eclipse Luna is not buggy. Well, actually, it is, but not because of this. This is the correct behaviour. — Dawood ibn Kareem
– Dawood ibn Kareem, Commented Oct 4, 2014 at 20:41

Dici · Accepted Answer · 2014-10-04 19:04:50Z

5

These outputs are perfectly correct. You have a 3-dimensional array of length 2 x 3 x 4 so for all valid indexes i, j :

a.length is 2
a[i].length is 3
a[i][j].length is 4

answered Oct 4, 2014 at 19:04

Dici

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2 Comments

Tien Do Nam Over a year ago

stackoverflow.com/questions/7367218/… ... so i just miss unterstood, thank you

Dici Over a year ago

If you look closely the answer of this question, the array is not declared the way you did. The person who answered did not specify the number of columns per row, and then allocated separately the rows with different lengths. That's why he's getting those outputs.

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