Create an array of strings and a string variable from dynamic args

Question

I am trying to achieve inputting n number of parameters as arguments to the java main function.

From these n parameters, n-1 of them are input file and the nth one is output file.

public static void main(String[] args) {

    List<String> stringList = new ArrayList<String>();
    String xlsxFileAddress;
    for (int i = 0; i < args.length - 1; i++) {
        stringList.add(args[i].toString());
    }
    String[] csvFileAddress = (String[]) stringList.toArray();

    xlsxFileAddress = args[args.length - 1];
    for (int i = 0; i < 2; i++) {
        System.out.println(csvFileAddress[i]);
    }

    System.out.println(xlsxFileAddress);
    csvToXLSX(csvFileAddress, xlsxFileAddress);
}

But this is throwing the following error -

Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.String;
    at com.jcg.csv2excel.CsvToExcel.main(CsvToExcel.java:109)

Óscar López · Accepted Answer · 2019-12-05 15:47:52Z

3

You need to use the toArray() overloaded version that takes an array, this will indicate the proper type of the array to build so you won't have the class cast exception. Try this instead:

 String[] csvFileAddress = stringList.toArray(new String[stringList.size()]);

answered Dec 5, 2019 at 15:47

Óscar López

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Alain-Michel Chomnoue N · Accepted Answer · 2019-12-05 15:47:45Z

2

You need to specify the array type and size when you try to convert a list to array.

String[] csvFileAddress =stringList.toArray(new String[stringList.size()]);

answered Dec 5, 2019 at 15:47

Alain-Michel Chomnoue N

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Comments

Selaka Nanayakkara · Accepted Answer · 2019-12-05 15:49:08Z

0

toArray() will returns an Object[], regardless of generics. You could use the overloaded variant instead.

Use the following :

String[] csvFileAddress =stringList.toArray(new String[stringList.size()]);

answered Dec 5, 2019 at 15:49

Selaka Nanayakkara

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Sunil Dabburi · Accepted Answer · 2019-12-05 16:00:47Z

0

Two approaches to your problem

using toArray()

String[] csvFileAddress = stringList.toArray(new String[0])

using stream()

String[] csvFileAddress = stringList.stream().toArray(String[]::new)

answered Dec 5, 2019 at 16:00

Sunil Dabburi

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