How Can I Efficiently Create Comma-Delimited String Lists in Java?

Building Delimited String Lists in Java

You recently encountered a scenario in your Java application where you needed to create a comma-delimited list of values. While you came up with a rudimentary solution, it was inefficient due to the constant creation of strings. Inspired by Ruby's elegant join command, you sought an equivalent approach in Java.

Pre Java 8

Apache's commons lang library offers a StringUtils.join(java.lang.Iterable,char) method that mimics Ruby's join. This method efficiently joins an iterable of strings using the specified delimiter.

Java 8

Java 8 introduced built-in joining methods:

StringJoiner

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

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

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

String.join(CharSequence delimiter, Iterable elements)

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

These methods provide efficient and elegant ways to build delimited string lists in Java, mimicking the functionality you enjoyed in Ruby.

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