How to Efficiently Create Comma-Delimited Strings in Java?

 Building Comma-Delimited Strings in Java

In Java, assembling a list of values into a delimited string is a common requirement. While basic approaches involve iterative concatenation, cleaner alternatives exist.

Pre-Java 8:

Leverage Apache's commons lang library, which provides a StringUtils.join() method analogous to Ruby's join.

Java 8 onwards:

StringJoiner:

• Create a StringJoiner instance with the desired delimiter.
• Add elements to the joiner using the add() method.
• Convert the joiner to a string using toString().

String.join(delimiter, array):

• Use String.join() with the delimiter and an array of elements as arguments.
• This method concatenates the elements into a string separated by the delimiter.

String.join(delimiter, iterable):

• Similar to the previous method, but accepts an iterable collection of elements instead of an array.

Example:

// Using StringJoiner
List<String> list = new ArrayList<>();
list.add("element1");
list.add("element2");
StringJoiner joiner = new StringJoiner(",");
joiner.addAll(list);
String delimitedString = joiner.toString();

// Using String.join(array)
String[] elements = new String[] {"element1", "element2"};
String delimitedString = String.join(",", elements);

// Using String.join(iterable)
List<String> list2 = new ArrayList<>();
list2.add("element1");
list2.add("element2");
String delimitedString = String.join(",", list2);

These methods provide efficient and elegant solutions for creating delimited strings in Java, eliminating the need for multiple string creations and concatenation.

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