Question

How do I get the second dimension of an array if I don’t know it? array.length gives only the first dimension.

For example, in

public class B {
    public static void main(String [] main){
        int [] [] nir = new int [2] [3];
        System.out.println(nir.length);
    }
}

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2

How would I get the value of the second dimension of nir, which is 3?

Answer 1

which 3?

You’ve created a multi-dimentional array. nir is an array of int arrays; you’ve got two arrays of length three.

System.out.println(nir[0].length); 

would give you the length of your first array.

Also worth noting is that you don’t have to initialize a multi-dimensional array as you did, which means all the arrays don’t have to be the same length (or exist at all).

int nir[][] = new int[5][];
nir[0] = new int[5];
nir[1] = new int[3];
System.out.println(nir[0].length); // 5
System.out.println(nir[1].length); // 3
System.out.println(nir[2].length); // Null pointer exception