What's the best way to build a string of delimited items in Java?

Question

While working in a Java app, I recently needed to assemble a comma-delimited list of values to pass to another web service without knowing how many elements there would be i

Answer 1

Pre Java 8:

Apache's commons lang is your friend here - it provides a join method very similar to the one you refer to in Ruby:

StringUtils.join(java.lang.Iterable,char)

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Java 8:

Java 8 provides joining out of the box via StringJoiner and String.join(). The snippets below show how you can use them:

StringJoiner

StringJoiner joiner = new StringJoiner(",");
joiner.add("01").add("02").add("03");
String joinedString = joiner.toString(); // "01,02,03"

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String.join(CharSequence delimiter, CharSequence... elements))

String joinedString = String.join(" - ", "04", "05", "06"); // "04 - 05 - 06"

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String.join(CharSequence delimiter, Iterable elements)

List strings = new LinkedList<>();
strings.add("Java");strings.add("is");
strings.add("cool");
String message = String.join(" ", strings);
//message returned is: "Java is cool"