Finding the dimensionality of an array in Java

Question

Given some object o, I need to find its dimensionality (eg: for int[x][y][z] the dimensionality is 3), I figured that any appropriate method would be in the class of the object.

int dimensionality = o.getClass().getName().indexOf('L');

works, but its source refers to a native method, so I'm left getting the answer from a string, rather than directly.

If anyone knows a better way of doing this it would be appreciated (although more for the sake of curiosity than necessity).

Answer 1

Here's a recursive solution using Class.isArray:

static int getDimensionality(final Class<?> type) {
    if (type.isArray()) {
        return 1 + getDimensionality(type.getComponentType());
    }
    return 0;
}

public static void main (String[] args) {
    System.out.println(getDimensionality(int.class));       // 0
    System.out.println(getDimensionality(int[].class));     // 1
    System.out.println(getDimensionality(int[][].class));   // 2
    System.out.println(getDimensionality(int[][][].class)); // 3
}

Although as PM 77-1 points out, this is not truly a measure of dimensionality but of the depth of a jagged array in terms of its static type. There are no true multidimensional arrays in Java, just arrays of arrays.