How do I split a string in Java?

java

regex

string-splitting

pattern-matching

byAlex Kataev·Feb 13, 2025

Split a string in Java with split():

String text = "java-tips";
String[] parts = text.split("-");
// parts = ["java", "tips"] -> was once "java-tips", now a split personality

Do an existence check with text.contains("-") to verify a hyphen before splitting to avoid possibly redundant operations.

Escaping regex specials

Special characters such as ., |, ?, *, and + should be escaped using a backslash (\):

String input = "Section 4.2";
String[] sections = input.split("\\."); // Yes indeed, dot is a special character!
// sections = ["Section 4", "2"] -> Finally split into rightful sections

Alternatively, use Pattern.quote() for safe character handling:

String[] sections = input.split(Pattern.quote("."));

Including separators

Retain separators when splitting with lookarounds in your regex:

String[] partsIncluded = "apple-banana-cherry".split("(?<=-)");
// partsIncluded = ["apple-", "banana-", "cherry"] -> apple didn't fall far from the hyphen!

String[] partsAhead = "apple-banana-cherry".split("(?=-)");
// partsAhead = ["apple", "-banana", "-cherry"]

Result array size control

Control the size of the result array by specifying a limit parameter:

String[] limitParts = "apple-banana-cherry".split("-", 2);
// limitParts = ["apple", "banana-cherry"] -> Cherry has a new sidekick named banana!

Regex gymnastics and `Pattern`, `Matcher` usage

Convert regex patterns to Pattern objects and use Matcher for executing regex operations:

Pattern pattern = Pattern.compile("-");
Matcher matcher = pattern.matcher("java-tips-tools");
while(matcher.find()) {
    // Put your processing clothes on! We're going pattern-matching!
}

Fetch matched content with Matcher.group():

Pattern pattern = Pattern.compile("([A-Z]+)-([0-9]+)");
Matcher matcher = pattern.matcher("AB-123");
if(matcher.matches()) {
    String letters = matcher.group(1); // AB
    String numbers = matcher.group(2); // 123
    // Who said letter grades and numbers can't get along?
}

Error handling in splitsville

Handle unexpected formats with proper error management:

String ipAddress = "192-168-1-1";
String[] octets = ipAddress.split("-");
if(octets.length != 4) {
    throw new IllegalArgumentException("Invalid IP address format. We're strict on rules here!");
}

No regex? No problem!

The StringTokenizer class splits strings without the complications of regex:

StringTokenizer tokenizer = new StringTokenizer("java:tips:tools", ":");
while(tokenizer.hasMoreTokens()) {
    String token = tokenizer.nextToken();
    // Token party! Everyone's invited!
}

Conquer regex complexities

Achieving exact formations

Ensure a specific structure of input using capturing groups:

String input = "AB-100";
boolean isMatch = input.matches("([A-Z]{2})-(\\d+)");
// isMatch = true -> AB congratulates 100!

Navigating negation and quantities

Exclude certain characters using negative character classes:

String data = "apple!banana?cherry";
String[] words = data.split("[^a-zA-Z]+");
// words = ["apple", "banana", "cherry"] -> Uninvited special characters shown the door!

Use quantifiers like + to match one or more occurrences:

String serialNumbers = "A123-B456-C789";
String[] numbers = serialNumbers.split("-\\D+");
// numbers = ["A123", "B456", "C789"] -> Nothing can keep these numbers apart!