Split Strings by Delimiter in an Array

Splitting strings is a common operation in Java, especially when processing structured data. In this article, we will split each string in an array using a given delimiter and reconstruct the array with the resulting parts.

Understanding the Problem

We are given an array of strings, where each string contains multiple words or elements separated by a delimiter (e.g., comma, space, hyphen). Our goal is to split each string by the delimiter and store all resulting parts in a new array.

Example:

Each word pair is split by "-", and all resulting words are stored in a new array.

INPUT:
String[] words = {“apple-banana”, “grape-mango”, “peach-orange”};
String delimiter = “-“;

OUTPUT:
[“apple”, “banana”, “grape”, “mango”, “peach”, “orange”]

Approach to Solve the Problem

1. Iterate through each string in the array.
2. Use Java’s split() method to break each string using the delimiter.
3. Store all parts in a new list or array.

Java Program for Splitting Strings by a Delimiter (Using split() with an ArrayList)

The Java program efficiently concatenates an array of strings using a specified delimiter by leveraging StringBuilder to minimize unnecessary string creation.

package com.javacodepoint.stringarray;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class SplitStringsByDelimiter {

	// Method to split each string by the delimiter and reconstruct the array
	public static String[] splitStrings(String[] words, String delimiter) {
		List<String> resultList = new ArrayList<>();

		for (String word : words) {
			String[] parts = word.split(delimiter); // Split the string
			resultList.addAll(Arrays.asList(parts)); // Add parts to the list
		}

		return resultList.toArray(new String[0]); // Convert list to array
	}

	public static void main(String[] args) {
		// Example array of strings
		String[] words = { "apple-banana", "grape-mango", "peach-orange" };
		String delimiter = "-";

		// Split strings and reconstruct the array
		String[] result = splitStrings(words, delimiter);
		System.out.println("Reconstructed Array: " + Arrays.toString(result));
	}
}

OUTPUT:
Reconstructed Array: [apple, banana, grape, mango, peach, orange]

Alternative Approach: Using Java Streams

Java Streams API provides a functional way to split and flatten arrays.

import java.util.Arrays;
import java.util.stream.Stream;

public class SplitUsingStreams {
    public static void main(String[] args) {
        String[] words = {"apple-banana", "grape-mango", "peach-orange"};
        String delimiter = "-";

        String[] result = Arrays.stream(words)
                .flatMap(word -> Arrays.stream(word.split(delimiter)))
                .toArray(String[]::new);

        System.out.println("Reconstructed Array: " + Arrays.toString(result));
    }
}

Conclusion

This article explored different ways to split an array of strings by a delimiter and reconstruct it. We covered:

• Using split() with an ArrayList (Efficient & Readable).
• Using Java Streams (flatMap()) (Concise & Functional).

Understanding these methods helps in text processing, data manipulation, and coding interviews.

You can learn the Top 20 string array programs for interview preparation (Click here).