Cast a column of a 2D Object array as a 1D String array

Question

I am trying to cast a 2D Object array column as a 1D String array; I have no problem getting the data itself, but it is the data types which creates a run-time error:

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String cannot be cast to [Ljava.lang.String;

This is an example of the code fragment I am working with:

Object[][] currentData = BackOffice.getData();
String[] dataWanted = null;

    for (int i=0; i<currentData.length; i++)
        dataWanted = (String[])currentData[i][1];

I thought I could get away with casting using (String[]), but obviously not... any help appreciated!

Evan Mulawski · Accepted Answer · 2012-05-08 14:21:22Z

3

If I understand correctly, you want to do:

String[] dataWanted = new String[currentData.length];

for (int i=0; i<currentData.length; i++)
    dataWanted[i] = currentData[i][1];

answered May 8, 2012 at 14:21

Evan Mulawski

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1 Comment

dgBP Over a year ago

Yaaay, that is pretty much what I wanted, I can now happily cast using (String) before currentData[i][1]; thanks! Of course I needed to use dataWanted[i]... obvious!

dj18 · Accepted Answer · 2012-05-08 14:28:35Z

1

currentData is a 2D array of Objects, so currentData[i][1] evaluates to a single Object. dataWanted is an array of Strings. You can't cast a single Object into an array type. Additionally, arrays must be initialized with a size before inserting items. If you'd like to place each Object into the dataWanted array you'll want something like this:

String[] dataWanted = new String[currentData.length];
for (int i = 0; i < currentData.length; i++) {
    dataWanted[i] = (String)currentData[i][1];
}

If this isn't what you're trying to accomplish, then please edit your question to be more specific.

answered May 8, 2012 at 14:28

dj18

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