Split a string in Java, based on delimiter, only once, if delimiter appears after given index

Question

I was looking for a single step process to split a string, only once, based on a delimiter, only if the delimiter appears after certain index. For eg.

Input: String--> my-city-hasa-dash, Delimiter--> "-", index --> "3"

Though the first delimiter appears at 3rd position it is not > index supplied. so the regex should look for next occurrence of delimeter > index and split only once.

Output[]: {"mycity", "hasadash"}

Input: String--> m-ycityhasadash, Delimiter--> "-", index --> "3" Index of delimeter is less than the index supplied. So no split needed. Output[]: {"mycityhasadash"}

Answer 1

If you are using Java 8 you can use :

String[] output = Arrays.asList(
        str.replaceAll("^(.{0,2})-", "$1").split("-", 2))
        .stream()
        .map(x -> x.replace("-", ""))
        .toArray(String[]::new);

Outputs

my-city-hasa-dash - [mycity, hasadash]
m-ycityhasadash   - [mycityhasadash]

Details

• str.replaceAll("^(.{0,2})-", "$1") will replace all the - before the first three characters
• .split("-", 2) split your string two times
• .map(x -> x.replace("-", "")) replace all the the - in the result outputs
• .toArray(String[]::new) collect the result to an array

take a look at :

• https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#split-java.lang.String-int-
• Java - How split(regex, limit) method actually works?

Answer 2

You can use a combination of String::substring and String::indexOf to get it:

String str = "my-city-hasa-dash";
String delimiter = "-";
int fromIndex = 3;
int delimiterIndex = str.indexOf(delimiter, fromIndex);
String[] output = delimiterIndex < 0 ? new String[]{str} :
        new String[]{
                str.substring(0, delimiterIndex).replace(delimiter, ""),
                str.substring(delimiterIndex).replace(delimiter, "")
        };

Output:

[mycity, hasadash]

Answer 3

import java.util.Arrays;
import java.util.stream.Collectors;

public class Test {

  public static void main(String ... args) {
    String input = "my-city-hasa-dash";

    String[] tokens = splitAfterIndex(input, "-", 2);

    System.out.println(Arrays.toString(tokens));

  }

  public static String[] splitAfterIndex(String str, String delimeter, int index) {
    String[] tokens = str.split(delimeter);

    String first = Arrays.stream(tokens).limit(index).collect(Collectors.joining());
    String second = Arrays.stream(tokens).skip(index).collect(Collectors.joining());

    return new String[] {second.isEmpty() ? first : first , second} ;

  }



}