Sending a custom ArrayList through an Intent

Question

I'm having a problem when working with custom ArrayLists and trying to move them between activities. First I've declared a custom ArrayList in my first activity:

private ArrayList<String[]> dataArray = new ArrayList<String[]>();

Where each element of the ArrayList is an array of String elements.

Next, I put it into an intent with putExtra():

Intent int1 = new Intent(this, ManualModeActivity.class);
int1.putExtra(EXTRA_MESSAGE, dataArray);

Then, when I try to recover the ArrayList in my second Activity, I find that there's only a getStringArrayListExtra() method for ArrayList<String> elements, so it doesn't work with ArrayList<String[]> . I've been searching about this and all I find are examples with custom objects where the solution is to implement a Parcelable or Serialize interface on them. How could I do this with a "default" object like String[]? (Or maybe am I missing something about how interfaces works since I'm still a newbie in java?)

Answer 1

You can pass an ArrayList<E> the same way, if the E type is Serializable .

You would call the putExtra (String name, Serializable value) of Intent to store, and getSerializableExtra (String name) for retrieval.

Example:

ArrayList<String> myList = new ArrayList<String>();
intent.putExtra("mylist", myList);
In the other Activity:

ArrayList<String> myList = (ArrayList<String>) getIntent().getSerializableExtra("mylist");

Answer 2

Your code for sending the data from the first activity is correct.

For receiving data in the second activity use intent 's getSerializableExtra() method, something like:

ArrayList<String[]> data = (ArrayList<String[]>) getIntent().getSerializableExtra(EXTRA_MESSAGE);