Java Utililty Methods StringJoiner Usage

String capitalise(String string)
Returns a new string consisting of the characters in the specified String, with the first letter of each word capitalised, and the rest lower-case.

String[] words = string.split(" ");
StringJoiner builder = new StringJoiner(" ");
for (String word : words) {
 String capitalised = Character.toUpperCase(word.charAt(0)) + word.substring(1).toLowerCase();
 builder.add(capitalised);
return builder.toString();

String convertListToString(String[] stringList)
Given a string list, gets the text from the list in the following manner: apple, pear, pineapple

if (stringList == null || stringList.length == 0) {
 return "";
StringJoiner stringJoiner = new StringJoiner(", ");
for (String string : stringList) {
 stringJoiner.add(string);
return stringJoiner.toString();
...

String generateDeleteCommand(int deleteDisplayIndex)
Generates a delete command at the given displayed index.

StringJoiner commandJoiner = new StringJoiner(" ");
commandJoiner.add("delete").add(String.valueOf(deleteDisplayIndex));
return commandJoiner.toString();

String getTraceString(StackTraceElement[] stackTraceElements)
get Trace String

final StringJoiner sj = new StringJoiner(System.lineSeparator());
for (final StackTraceElement stackTraceElement : stackTraceElements) {
 sj.add(stackTraceElement.toString());
return sj.toString();

String implode(T[] array, String delim)
Based on implode() in PHP

final StringJoiner sj = new StringJoiner(delim);
for (T o : array) {
 sj.add(o.toString());
return sj.toString();

String implodeString(Iterable strings, String delimiter)
(Based on implode() in PHP)

final StringJoiner sj = new StringJoiner(delimiter);
strings.forEach(sj::add);
return sj.toString();

List incrementalComputationOfComponentWiseAverage(List average, int n, List newItems)
Incrementally calculates component-wise averages, given previously calculated averages (out of n numbers) and a list of new numbers.

if (average == null) {
 fatalError("Util.incrementalComputationOfComponentWiseAverage must receive a non-null List");
if (average.size() == 0) {
 for (int i = 0; i != newItems.size(); i++) {
 average.add(new Double(0));
for (int i = 0; i != newItems.size(); i++) {
 double currentAverage = ((Double) average.get(i)).doubleValue();
 double newItem = ((Double) newItems.get(i)).doubleValue();
 double newAverage = (currentAverage * n + newItem) / (n + 1);
 average.set(i, new Double(newAverage));
return average;

String join(Collection data, String delimiter)
join

return join(data, new StringJoiner(delimiter));

String join(final String left, final String right)
join

return new StringJoiner(".").add(left).add(right).toString();

String join(String separator, Collection c)
Returns a string formed by the concatenation of string versions of the elements in a collection, separated by a given separator.

Iterator it = c.iterator();
return join(separator, it);