Converting List<String> to comma separated string in java8 is very simple and straight forward, with String join We simply can write String.join(..), pass a delimiter and an Iterable and the new StringJoiner will do the rest. If we are working with a stream we can write it using Collectors.
Here is the CSVUtil class and couple of tests.
package com.jminded.java8;
import java.util.List;
import static java.util.stream.Collectors.joining;
/**
* https://jminded.com
*
* @author Umashankar
*
*/
public class CSVUtil {
private static final String SEPARATOR = ",";
/**
*
* @param listToConvert
* @return
*/
public static String toCsv(List<String> listToConvert) {
return String.join(SEPARATOR, listToConvert);
}
/**
*
* @param listToConvert
* @return
*/
public static String toCsvStream(List<String> listToConvert) {
return listToConvert.stream().collect(joining(SEPARATOR));
}
}
package com.jminded.java8;
import java.util.Arrays;
import java.util.List;
import org.junit.Test;
import static org.junit.Assert.assertEquals;
/**
* https://jminded.com
*
* @author Umashankar
*
*/
public class CSVUtilTest {
@Test
public void toCsv_csvFromListOfString() {
List<String> securities = Arrays.asList("Stock", "Future", "Option", "Forex", "ETF");
String expected = "Stock,Future,Option,Forex,ETF";
assertEquals(expected, CSVUtil.toCsv(securities));
}
@Test
public void toCsvStream_csvFromListOfString() {
List<String> securities = Arrays.asList("Stock", "Future", "Option", "Forex", "ETF");
String expected = "Stock,Future,Option,Forex,ETF";
assertEquals(expected, CSVUtil.toCsvStream(securities));
}
}