Need help casting from a List<String[]> to an Array

Question

I am using the csvparser library from univocity and am having trouble converting a List object in to an array that would be easily read from.

The method that keeps throwing an ArrayStoreException is:

List<String[]> resolvedData;
String[] array = new String[7000];

public void parseURLs() throws FileNotFoundException {

    CsvParserSettings settings = new CsvParserSettings();
    settings.getFormat().setLineSeparator("\n");
    CsvParser parser = new CsvParser(settings);

    try {
        resolvedData = parser.parseAll(new FileReader("C:\\Users\\kevin.anderson\\Desktop\\book1.csv"));
        resolvedData.toArray(array);
    } catch (Exception ex) {
        System.out.println(ex.toString());

    }
}

Is there a way to get the items out of a List into an array or is there an easy way to iterate thru the items in the List string array?

Thank you

How are you going to put String[] values into a String[]? — Sotirios Delimanolis
– Sotirios Delimanolis, Commented Jan 7, 2016 at 17:14
I presume that each line, which is captured by a String[], is captured in the list. The next question would be, what do you intend to do with the result? — Makoto
– Makoto, Commented Jan 7, 2016 at 17:17
Why the downvote? This is a beginner problem, but well stated and backed up by what has been tried. It's also probably an XY Problem but that is typical for beginners and shouldn't merit a downvote. — Jim Garrison
– Jim Garrison, Commented Jan 7, 2016 at 17:47

Jim Garrison · Accepted Answer · 2016-01-07 17:43:49Z

1

I think this is an XY problem. There is no need to convert the data to an array in order to iterate over it, so I'll give the answer I think you're looking for, which is how to iterate easily over a List<String[]> that you're receiving from the CSV parser.

for (String[] currentLine : resolvedData)
{
    // currentLine here is a String[] containing the fields from one CSV record
    // To iterate over the fields
    for (String field : currentLine)
    {
        // do something with each field
    }
 // --- OR ---
    // To access fields by index
    String firstField = currentLine[0];
    // do something with firstField
}

answered Jan 7, 2016 at 17:43

Jim Garrison

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Comments

Mike Murphy · Accepted Answer · 2016-01-07 17:35:35Z

Try this.

    List<String[]> resolvedData;
    String[][] array;

    public void parseURLs() throws FileNotFoundException {

        CsvParserSettings settings = new CsvParserSettings();
        settings.getFormat().setLineSeparator("\n");
        CsvParser parser = new CsvParser(settings);

        try {
            resolvedData = parser.parseAll(new FileReader("C:\\Users\\kevin.anderson\\Desktop\\book1.csv"));
            array = new String[resolvedData.size()][];
            resolvedData.toArray(array);
        } catch (Exception ex) {
            System.out.println(ex.toString());
        }
    }

Basic errors you assumed a fixed size of the incoming list of 7000 and also a single dimension array which is addressed with

String[][] array = new String[resolvedData.size()][];

user2626585 · Accepted Answer · 2016-01-07 17:23:57Z

0

You get this ArrayStoreException because the list resolvedData contains String[] elements and not String.

See https://docs.oracle.com/javase/7/docs/api/java/lang/ArrayStoreException.html for details.

answered Jan 7, 2016 at 17:23

user2626585

Comments

whistling_marmot · Accepted Answer · 2016-01-07 17:28:41Z

0

@Daruisz is right. resolvedData.toArray() will produce an array of arrays:

    String[] array1 = {"1a", "1b"};
    String[] array2 = {"2a", "2b"};
    String[] array3 = {"3a", "3b", "3c"};
    List<String[]> data = Arrays.asList(array1, array2, array3);
    String[][] arrayOfArrays = data.toArray(new String[0][0]);

answered Jan 7, 2016 at 17:28

whistling_marmot

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