Java API to convert Array to CSV

Question

Suppose I have an array of int, float, string etc. Is there any utility API (e.g. Commons, Guava) that will give me a comma separated string?

Like so,

int[] a = {1,2,3,4,5}. 
String s = magicAPI.getCSV(a); // s == "1,2,3,4,5";

@rascio Arrays#toString also inserts spaces after each comma, which you can't remove easily with a regex as it might be part of a String (in the case of a String[]). — assylias
– assylias, Commented Jul 18, 2012 at 16:31
@assylias Although in that case you probably need to handle the case of the delimiter being part of the string more generally. (By using a full CSV library for instance. — millimoose
– millimoose, Commented Jul 18, 2012 at 16:34
it was a joke it's the most stupid way I found to do it...it's plenty of better way to do it :) — rascio
– rascio, Commented Jul 18, 2012 at 16:34

assylias · Accepted Answer · 2014-09-18 18:18:54Z

33

For this simple use case, you can simply join the strings with comma. If you use Java 8:

String csv = String.join(",", yourArray);

otherwise commons-lang has a join() method:

String csv = org.apache.commons.lang3.StringUtils.join(yourArray, ",");

edited Sep 18, 2014 at 18:18

answered Jul 18, 2012 at 16:29

assylias

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1 Comment

Boris Daich Over a year ago

getting The method join(CharSequence, CharSequence...) in the type String is not applicable for the arguments (String, int[]) what do I miss?

millimoose · Accepted Answer · 2012-07-18 16:32:58Z

6

You mention Google Guava, which has the Joiner utility for this:

String s = Joiner.on(",").join(a);

answered Jul 18, 2012 at 16:32

millimoose

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Comments

munyengm · Accepted Answer · 2012-07-18 16:40:56Z

4

I've used OpenCSV in the past.

StringWriter stringWriter = new StringWriter();
int[] a = {1,2,3,4,5};
String[] b = new String[a.length];
for ( int i = 0; i < a.length; i++) {
    b[i] = a[i];
}
CSVWriter csvWriter = new CSVWriter(stringWriter, ",");
csvWriter.writeNext(b);

However, for such a trivial example you might want to just use the a StringBuilder and a for loop

edited Jul 18, 2012 at 16:40

answered Jul 18, 2012 at 16:29

munyengm

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2 Comments

Brian Agnew Over a year ago

Doesn't the writeNext() method NOT require you to insert commas yourself ? Otherwise what's the point ?

Hack-R Over a year ago

Is there a vectorized version of this?

Anand Hemmige · Accepted Answer · 2012-07-18 16:34:36Z

3

After digging more, I found http://static.springsource.org/spring/docs/1.1.5/api/org/springframework/util/StringUtils.html StringUtils API in Spring that can do it. Since , I'm already using Spring, I guess I will stick with it.

answered Jul 18, 2012 at 16:34

Anand Hemmige

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Comments

Brian Agnew · Accepted Answer · 2012-07-18 16:27:45Z

1

Commons Apache CSV appears to consolidate 3 other CSV libraries, although I can't find a release post-2007.

A quick look suggests OpenCSV will do what you want via a CSVWriter.

 CSVWriter writer = new CSVWriter(new FileWriter("yourfile.csv"), '\t');
 // feed in your array (or convert your data to an array)
 String[] entries = "first#second#third".split("#");

answered Jul 18, 2012 at 16:27

Brian Agnew

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Comments

Yogamurthy · Accepted Answer · 2016-07-11 01:04:52Z

0

I have created a new method to do thisinstead of going for openCSV

public String convertArrayToCsv(String[] IncomingArray)
{
    StringBuilder sb=new StringBuilder();
    for (int i=0;i<IncomingArray.length;i++)
    {
        sb=sb.append(IncomingArray[i]);
        if(i != IncomingArray.length-1)
        {
            sb.append(",");
        }
    }
    return sb.toString();
}//end of convertArrayToCsv method

edited Jul 11, 2016 at 1:04

answered Jul 11, 2016 at 0:58

Yogamurthy

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