Find the dimension of array

Question

I know its a silly question but I want to know that Is it possible to find the array dimension? when we have the following code

public class ArrayDimentionCheck {

  public static void main(String[] args) {
    Integer[][] arr = { { 1, 2 }, { 2, 3 } };
    printDimension(arr);
    Integer[][] arr1 = { { 1, 2, 4 }, { 2, 3, 6 } };
    printDimension(arr1);
  }

  private static void printDimension(Object arr) {
    System.out.println("given object dimension:");
  }
}

Can we write some generic code in printDimension method to identify the array dimension??

possible duplicate of [Array's length property](http://stackoverflow.com/questions/9297899/arrays-length-property) — hivert, Apr 02 '14 at 07:17
It is not a duplicate question, what we do when we have nxn dimensional array ?? — Rakesh Chouhan, Apr 02 '14 at 07:21
@Rakesh Yes, what I mean is: do you want to know the number of elements in the array, or the dimension? `int[][][]` would be dimension `3`, `int[][]` would be dimension `2`. In your code, both arrays have a dimension of `2`, but with different lengths in each "row" — Andreas Fester, Apr 02 '14 at 07:24

Filipp Voronov · Answer 1 · 2014-04-02T08:13:21.027

but I want result in following format for arr it should be 2x2 and arr1 3x2

You should know, that in java you can do this:

Integer[][] arr = { { 1, 2 }, { 1, 3, 4, 5 } };

So the code below doesn't work for jagged arrays.

Also it doesn't work for 0-length arrays such as:

new boolean[11][0][4]

Here the code is:

public static void printDimension(Object array) {
    if (array == null) {
        System.out.println("Object is null!");
        return;
    }

    if (!array.getClass().isArray()) {
        System.out.println("Object is not array!");
        return;
    }

    String ans = "";
    Object cur = array;
    while (cur != null && cur.getClass().isArray()) {
        ans += "x" + Array.getLength(cur);

        if (!cur.getClass().getComponentType().isPrimitive()) {
            cur = ((Object[]) cur)[0];
        } else {
            break;
        }
    }

    System.out.println(ans.substring(1));
}

Example of usage:

printDimension(new boolean[1][11]);
printDimension(new boolean[1][11][4]);
printDimension(new Integer[14][88]);

Output:

1x11
1x11x4
14x88

@RakeshChouhan, I think in this case you should accept my answer ;) — Filipp Voronov, Apr 02 '14 at 09:34

score 2 · Answer 2 · edited May 23 '17 at 10:26

2

2-D array is a array of arrays. So each array can have variable length (which represents columns in case of 2-D array). You can get length of individual arrays using

args[0].length;
args[1].length;

and so on

and length of whole 2-D array using

args.length

which is number of rows in 2-D array.

Related question: Multi-Dimension length array reflection java

edited May 23 '17 at 10:26

Community

1
1

answered Apr 02 '14 at 07:18

Ajinkya

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1

what we do when we have nxn dimensional array ?? – Rakesh Chouhan Apr 02 '14 at 07:21
I have added link to my answer. – Ajinkya Apr 02 '14 at 07:56

score 1 · Answer 3 · answered Apr 02 '14 at 07:18

you can use Array.lenght to know the lenght .. and by using this you can find the dimension . for example

    int xx = arr.length;  // will return the number of row
    int yy = arr[0].length;  // will return the number of column

N.B. assuming that every row has same number of columns

Subhrajyoti Majumder · Answer 4 · 2014-04-02T08:54:15.710

1

I think you are asking obj is single dimension or double dimension or ... of array type.

private static void printDimension(Object arr) {
    final String className = arr.getClass().toString();
    Pattern pattern = Pattern.compile("([\\[])");
    Matcher matcher = pattern.matcher(className);
    int count = 0;
    while (matcher.find()) count++;
    int length = count>1?((Object[][])arr)[0].length:0;
    System.out.println("given object dimension:"+count+"x"+length);
}

...

Integer[][][] arr = new Integer[3][2][2];
printDimension(arr);
Integer[] arr1 = {};
printDimension(arr1);
printDimension(new Object());

result :

given object dimension:3x2
given object dimension:1x0
given object dimension:0x0

edited Apr 02 '14 at 08:54

answered Apr 02 '14 at 07:26

Subhrajyoti Majumder

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Thanks @Subhrajyoti but I want result in following format for arr it should be 2x2 and arr1 3x2 – Rakesh Chouhan Apr 02 '14 at 07:32
`args[0].length` will help you get that detail – Subhrajyoti Majumder Apr 02 '14 at 07:39

score 1 · Answer 5 · answered Apr 02 '14 at 07:47

You can find the dimensions of an array using recursion and reflection.

Given the method dimensions:

private int dimensions(Class arrayType)
{
  return arrayType.isArray() ? 1 + dimensions(arrayType.getComponentType()) : 0
}

When calling the dimensions method like this:

int[] oneDimensionalArray = new int[0];
int[][] twoDimensionalArray = new int[0][0];
int[][][] threeDimensionalArray = new int[0][0][0];

System.out.println(dimensions(oneDimensionalArray.getClass()));
System.out.println(dimensions(twoDimensionalArray.getClass()));
System.out.println(dimensions(threeDimensionalArray.getClass()));

Will print:

1
2
3

Find the dimension of array

5 Answers5