java - How to remove element from an array

Question

I have an array for example:

String [][] test = {{"a","1"},
                    {"b","1"},
                    {"c","1"}};

Can anyone tell me how to remove an element from the array. For example I want to remove item "b", so that the array looks like:

{{"a","1"},
 {"c","1"}}

I can't find a way of doing it. What I have found here so far is not working for me :(

Answer 1

You cannot remove an element from an array. The size of a Java array is determined when the array is allocated, and cannot be changed. The best you can do is:

• Assign null to the array at the relevant position; e.g.

  test[1] = null;
  

  This leaves you with the problem of dealing with the "holes" in the array where the null values are. (In some cases this is not a problem ... but in most cases it is.)

• Create a new array with the element removed; e.g.

  String[][] tmp = new String[test.length - 1][];
  int j = 0;
  for (int i = 0; i < test.length; i++) {
      if (i != indexOfItemToRemove) {
          tmp[j++] = test[i];
      }
  }
  test = tmp;
  

  The Apache Commons ArrayUtils class has some static methods that will do this more neatly (e.g. Object[] ArrayUtils.remove(Object[], int), but the fact remains that this approach creates a new array object.

A better approach would be to use a suitable Collection type. For instance, the ArrayList type has a method that allows you to remove the element at a given position.