Let's say you have a comma delimited file or a phrase that you want to divide each element on all the commas. This example will show how to parse a string on a comma using java, guava and apache commons. A similar example shows how to parse comma delimited string in groovy.
Straight up Java
Using java's core String.split function we will pass a regular expression that will return an array of strings computed by splitting the original on a comma.
@Test
public void split_string_comma_java() {
String[] elementsInString = "Yo,Gabba, Gabba, Keep Trying".split(",");
logger.info(Arrays.toString(elementsInString));
assertTrue(elementsInString.length == 4);
}Java 8
Creating a stream from a string then applying the java 8 function to the elements will produce an Arraylist of String arrays. Calling the flatmap will replace or combine each array into a single stream by flattening it. Finally we will convert stream into arraylist.
@Test
public void split_string_comma_java8() {
List<String> splitByComma = Stream.of("Yo,Gabba, Gabba, Keep Trying")
.map(w -> w.split(",")).flatMap(Arrays::stream)
.collect(Collectors.toList());
logger.info(splitByComma);
assertTrue(splitByComma.size() == 4);
}Google Guava
Using guava's Splitter class we will parse a comma delimited string by passing a comma as a separator to the on method. Next we will call the splitToList function that will split the sequence into chunks and make them available via an ArrayList.
@Test
public void split_string_comma_guava() {
List<String> elementsInString = Splitter.on(",").splitToList(
"Yo,Gabba, Gabba, Keep Trying");
logger.info(elementsInString);
assertEquals(4, elementsInString.size());
}Apache Commons
This snippet will split text into an array using a comma as a separator using apache commons StringUtils.split.
@Test
public void split_string_white_space_using_apache_commons() {
String[] elementsInString = StringUtils.split(
"Yo,Gabba, Gabba, Keep Trying", ",");
logger.info(Arrays.toString(elementsInString));
assertTrue(elementsInString.length == 4);
}