Variable dimensioned array in Java?

Question

switch (dimensions) {
    case 1:  double[] array = new double[10];                     break;
    case 2:  double[][] array = new double[10][];                 break;
    case 3:  double[][][] array =  new double[10][][];            break;
    case 4:  double[][][][] array = new double[10][][][];         break;
    case 5:  double[][][][][] array = new double[10][][][][];     break;
    case 6:  double[][][][][][] array = new double[10][][][][][]; break;
    default: System.out.println("Sorry, too many dimensions");    break;
}

Is there a way to do the above in a better way? I want it to be able to create an array of any number of dimensions, also...

jberg · Accepted Answer · 2011-04-14 23:53:28Z

9

I would just use flat 1-dimensional arrays and index based on dimension, i and j.

answered Apr 14, 2011 at 23:53

jberg

4,8262 gold badges22 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Romain Over a year ago

I would actually argue the need to use a primitive array there, as opposed to writing an abstraction over it that creates the "arbitrary amount of dimensions" paradigm and hides the actual storage. It may be dependent on the actual usage pattern though.

aroth Over a year ago

+1 Multi-dimensional arrays are not useful, particularly in object-oriented languages that make it trivial to wrap your array in some more meaningful data structure. Just use a flat array and interpolate your indices.

Paŭlo Ebermann · Accepted Answer · 2011-04-15 00:46:24Z

As already said, you can't really use such an array, as you would need different code for each dimension.

Creating such an array is doable, though, using reflection:

 import java.lang.reflect.Array;

 private Class<?> arrayClass(Class<?> compClass, int dimensions) {
     if(dimensions == 0) {
        return compClass;
     }
     int[] dims = new int[dimensions];
     Object dummy = Array.newInstance(compClass, dims);
     return dummy.getClass();
 }

 public Object makeArray(int dimensions) {
     Class<?> compType = arrayClass(double.class, dimensions-1);
     return Array.newInstance(compType, 10);
 }

You then would have to use reflection to access your array, or cast it to Object[] (which works for all dimensions > 1), and then manipulate only the first level. Or feed it to a method which needs the right type of array.

Collectives™ on Stack Overflow

Variable dimensioned array in Java?

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related