How do I know how big to make my array for Parcel.readStringArray()?

Question

I'm getting a null pointer exception when I do this:

    private String[] foo;

    private void readFromParcel(Parcel in) {
        in.readStringArray(foo);
    }

It seems I need to allocate the array first. But how do I know how big to make it? Do I have to write the size first and then read the size first? And isn't the point of having a writeStringArray() method to handle this for me?

From the Android Documentation:

There are a variety of methods for reading and writing raw arrays of primitive objects, which generally result in writing a 4-byte length followed by the primitive data items.

So, if I write the count myself, it's getting written twice. There must be some way of doing this where I am not responsible for managing this.

score 5 · Accepted Answer · answered Aug 24 '11 at 18:53

5

I know this is not a direct answer, but you can use lists (ArrayList<String>) instead with writeList() and createStringArrayList().

Or you could use Parcle#createStringArray() to get the array.

answered Aug 24 '11 at 18:53

MByD

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Well, the problem is the underlying data type is tied to a schema that spans multiple components. And it's a `String[]`. I could write code to convert it to an `ArrayList<>` and back, but I shouldn't have to. – i_am_jorf Aug 24 '11 at 19:47
1

And what about `createStringArray`? – MByD Aug 24 '11 at 19:48
Ah, that looks like what I need. Let me test it. – i_am_jorf Aug 24 '11 at 19:50
Yeah, I knew there had to be away. My psychic powers failed me on the name. – i_am_jorf Aug 24 '11 at 20:28

score 2 · Answer 2 · answered Aug 24 '11 at 18:55

I'd expect you'd have to do something like this:

private String[] foo;
private void readFromParcel(Parcel in) {
        int cnt = in.readInt();
        foo = new String[cnt];
        in.readStringArray(foo);
    }

which implies you have to record the size of the array when writing out.

How do I know how big to make my array for Parcel.readStringArray()?

2 Answers2