How to change array elements?

Import array to arraylist except null elements?

• Another java newbie question. How can I import an array into an arraylist except null values? I find array to be unyielding when it comes to moving around and removing elements and reducing/increasing the size of the array. I need to use array during the first part of the program for indexing purposes and export the contents to an arraylist except null elements. The latter part of my program needs iteration using the new arraysize trimmed to actual number of elements where trimtosize is very helpful. The actual problem I have with using arraylist at the very beginning is that when I set an element value to null, it affects the values of succeeding elements. For example i have an arraylist of 1, 2, 3, 4, 5. If I set the value of index 2 to null, the output becomes 1,2, null, 3, 4, so now I'm missing 5. It's easier to remove it instead of setting it to null but the index of the elements are crucial... If you can suggest a way I can set element values to null without having the other elements affected it would be better.. Many thanks in advance.

• Answer:

  I don't think that's possible, although I could see how you might think that's possible, since an array is an object. The collections classes are useful because they have that functionality built in. You can use Arrays.toList() to transform an array into a list. I think List.add() will return false, for null data. It seems like you want to add a null value at an index. Have you tried using List.add(T value, int index)?