Join multiple strings in Java using a delimiter

This post will discuss how to join multiple strings in Java (specified as an array, Iterable, varargs, etc.) with a delimiter.

1. Using Loop

The idea is to loop through the collection and append each element to a string separated by a delimiter. The variable prefix is used to avoid adding a delimiter at the end of the output.

import java.util.Arrays;

import java.util.List;

// Program to join multiple strings in Java using a delimiter

class Main

{

public static void main(String[] args)

{

List<String> alphabets = Arrays.asList("A", "B", "C", "D");

String delimiter = ",";

String result = "", prefix = "";

for (String s: alphabets)

{

result += prefix + s;

prefix = delimiter;

}

System.out.println(result);

}

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Output:

A,B,C,D

2. Using Java 8 `String.join()` method

From Java 8 onward, we can use the String.join() method, which joins strings together with a specified separator. This method only works on Iterable and varargs.

import java.util.Arrays;

import java.util.List;

// Program to join multiple strings in Java 8 and above using a delimiter

class Main

{

public static void main(String[] args)

{

List<String> alphabets = Arrays.asList("A", "B", "C", "D");

String delimiter = ",";

String result = String.join(delimiter, alphabets);

System.out.println(result);

}

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Output:

A,B,C,D

3. Using Guava’s `Joiner` Class

Like the String.join() method, Guava provides Joiner class, which joins elements of a collection (say, iterable, iterator, or Object[]) with a separator.

import com.google.common.base.Joiner;

import java.util.Arrays;

import java.util.List;

// Program to join multiple strings using a delimiter with Guava

class Main

{

public static void main(String[] args)

{

List<String> alphabets = Arrays.asList("A", "B", "C", "D");

String delimiter = ",";

String result = Joiner.on(delimiter)

.useForNull("null")

.join(alphabets);

System.out.println(result);

}

Download Code

Output:

A,B,C,D

That’s all about joining multiple strings in Java using a delimiter.

Join multiple strings in Java using a delimiter

1. Using Loop

2. Using Java 8 String.join() method

3. Using Guava’s Joiner Class

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2. Using Java 8 `String.join()` method

3. Using Guava’s `Joiner` Class