Java String split()

class Main {
  public static void main(String[] args) {
    String text = "Java is a fun programming language";

    // split string from space
    String[] result = text.split(" ");


    System.out.print("result = ");
    for (String str : result) {
      System.out.print(str + ", ");
    }
  }
}

// Output: result = Java, is, a, fun, programming, language,

Syntax of String split()

The syntax of the string split() method is:

string.split(String regex, int limit)

Here, string is an object of the String class.

split() Parameters

The string split() method can take two parameters:

• regex - the string is divided at this regex (can be strings)
• limit (optional) - controls the number of resulting substrings

If the limit parameter is not passed, split() returns all possible substrings.

split() Return Value

• returns an array of substrings

Note: If the regular expression passed to split() is invalid, the split() method raises PatternSyntaxExpression exception.

Example 1: split() Without limit Parameter

// importing Arrays to convert array to string
// used for printing arrays
import java.util.Arrays;

class Main {
  public static void main(String[] args) {
    String vowels = "a::b::c::d:e";

    // splitting the string at "::"
    // storing the result in an array of strings
    String[] result = vowels.split("::");


    // converting array to string and printing it
    System.out.println("result = " + Arrays.toString(result));
  }
}

Output

result = [a, b, c, d:e]

Here, we split the string at ::. Since the limit parameter is not passed, the returned array contains all the substrings.

split() With limit Parameter

• If the limit parameter is 0 or negative, split() returns an array containing all substrings.
• If the limit parameter is positive (let's say n), split() returns the maximum of n substrings.

Example 2: split() With limit Parameter

// importing Arrays to convert array to string
import java.util.Arrays;

class Main {
  public static void main(String[] args) {
    String vowels = "a:bc:de:fg:h";

    // splitting array at ":"

    // limit is -2; array contains all substrings
    String[] result = vowels.split(":", -2);

    System.out.println("result when limit is -2 = " + Arrays.toString(result));

    // limit is 0; array contains all substrings
    result = vowels.split(":", 0);
    System.out.println("result when limit is 0 = " + Arrays.toString(result));

    // limit is 2; array contains a maximum of 2 substrings
    result = vowels.split(":", 2);
    System.out.println("result when limit is 2 = " + Arrays.toString(result));

    // limit is 4; array contains a maximum of 4 substrings
    result = vowels.split(":", 4);
    System.out.println("result when limit is 4 = " + Arrays.toString(result));

    // limit is 10; array contains a maximum of 10 substrings
    result = vowels.split(":", 10);
    System.out.println("result when limit is 10 = " + Arrays.toString(result));
  }
}

Output

result when limit is -2 = [a, bc, de, fg, h]
result when limit is 0 = [a, bc, de, fg, h]
result when limit is 2 = [a, bc:de:fg:h]
result when limit is 4 = [a, bc, de, fg:h]
result when limit is 10 = [a, bc, de, fg, h]

Note: The split() method takes regex as the first argument. If you need to use special characters such as: \, |, ^, *, + etc, you need to escape these characters. For example, we need to use \\+ to split at +.

Example 3: split() at the + character

// importing Arrays to convert array to string
// used for printing arrays
import java.util.Arrays;

class Main {
  public static void main(String[] args) {
    String vowels = "a+e+f";

    // splitting the string at "+"
    String[] result = vowels.split("\\+");


    // converting array to string and printing it
    System.out.println("result = " + Arrays.toString(result));
  }
}

Output

result = [a, e, f]

Here, to split a string at +, we have used \\+. It's because + is a special character (has a special meaning in regular expressions).