Split a String in Java using dot, dollar, or question mark as a delimiter

This post will explore different ways to split a string in Java using the dot (.), pipe (|) or dollar ($) or question mark (?) as a delimiter.

1. Using `String.split()` method

The standard solution is to use the split() method provided by the String class. It takes a regular expression as a delimiter and returns a string array.

import java.util.Arrays;

class Main

{

public static void main(String[] args)

{

String ip = "127.0.0.1";

String[] result = ip.split(".");

System.out.println(Arrays.toString(result)); // output: []

}

Download Run Code

If we run the above code, it doesn’t work as expected. This is because the split() method takes a regular expression, and the dot is a special character that matches any character in the regex. We can avoid this behavior by creating a regex that will represent a dot. There are several ways to do this, which are covered below in detail:

⮚ Using an escape character

We can make the above code work by escaping the dot character. An escape character invokes an alternative interpretation on the following characters of a string. In Java, the \ (backslash) is used to escape special characters. Note that Java follows the two backslash-escape styles.

import java.util.Arrays;

class Main

{

public static void main(String[] args)

{

String ip = "127.0.0.1";

String[] result = ip.split("\\.");

System.out.println(Arrays.toString(result)); // output: [127, 0, 0, 1]

}

Download Run Code

⮚ Wrapping dot between \Q and \E

Another plausible way of escaping is using \Q to backslash all subsequent special characters and \E to end the expression.

import java.util.Arrays;

class Main

{

public static void main(String[] args)

{

String ip = "127.0.0.1";

String[] result = ip.split("\\Q.\\E");

System.out.println(Arrays.toString(result)); // output: [127, 0, 0, 1]

}

Download Run Code

⮚ Character Class

We can also use Character class in Java for escaping the dot (.), as shown below:

import java.util.Arrays;

class Main

{

public static void main(String[] args)

{

String ip = "127.0.0.1";

String[] result = ip.split("[.]");

System.out.println(Arrays.toString(result)); // output: [127, 0, 0, 1]

}

Download Run Code

⮚ Pattern.quote()

Another good alternative is to use the Pattern.quote(), which returns a literal pattern string for the specified string.

import java.util.Arrays;

import java.util.regex.Pattern;

class Main

{

public static void main(String[] args)

{

String ip = "127.0.0.1";

String[] result = ip.split(Pattern.quote("."));

System.out.println(Arrays.toString(result)); // output: [127, 0, 0, 1]

}

Download Run Code

2. Using Guava’s `Splitter` Class

We can use the Splitter class from the Guava library, as shown below, which returns an Iterable.

import com.google.common.base.Splitter;

class Main

{

public static void main(String[] args)

{

String ip = "127.0.0.1";

Iterable<String> result = Splitter.on(".").split(ip);

System.out.println(result); // output: [127, 0, 0, 1]

}

Download Code

3. Using Apache Commons Lang

We can also leverage the StringUtils.split() method of Apache Commons Lang library, which splits the string into an array using a specified delimiter.

import org.apache.commons.lang3.StringUtils;

import java.util.Arrays;

class Main

{

public static void main(String[] args)

{

String ip = "AB.X.Y";

String[] result = StringUtils.split(ip, ".");

System.out.println(Arrays.toString(result)); // output: [127, 0, 0, 1]

}

Download Code

4. Using `StringTokenizer` Class

The StringTokenizer is a legacy class that allows breaking a string into tokens using a delimiter, as shown below:

import java.util.ArrayList;

import java.util.List;

import java.util.StringTokenizer;

class Main

{

public static void main(String[] args)

{

String ip = "127.0.0.1";

StringTokenizer st = new StringTokenizer(ip, ".");

List<String> result = new ArrayList<>();

while (st.hasMoreTokens()) {

result.add(st.nextToken());

}

System.out.println(result); // output: [127, 0, 0, 1]

}

Download Run Code

That’s all about splitting a Java String using dot, dollar, or question mark as a delimiter.

Split a String in Java using dot, dollar, or question mark as a delimiter

1. Using String.split() method

2. Using Guava’s Splitter Class

3. Using Apache Commons Lang

4. Using StringTokenizer Class

Share this:

1. Using `String.split()` method

2. Using Guava’s `Splitter` Class

4. Using `StringTokenizer` Class