How to Optimize String Splitting Performance in Java

What are some efficient alternatives to the String.split() method in Java for optimizing performance?

String[] ids = str.split("/"); // Current code for splitting a string

String splitting can significantly impact application performance, particularly when dealing with large strings or frequent calls. The standard String.split() method in Java uses regular expressions, which may introduce unnecessary overhead. This article discusses optimized alternatives for splitting strings efficiently in Java.

String str = "one/two/three";
String[] ids = str.split("/"); // This is the original code

// Alternative using StringUtils
import org.apache.commons.lang3.StringUtils;
String[] ids = StringUtils.split(str, '/');

// Using indexOf() and substring to manually split
List<String> tokens = new ArrayList<>();
int start = 0;
int end = str.indexOf('/');
while (end != -1) {
    tokens.add(str.substring(start, end));
    start = end + 1;
    end = str.indexOf('/', start);
}
tokens.add(str.substring(start)); // add last token
String[] idsArray = tokens.toArray(new String[0]); // convert List to Array

Causes

• String.split() uses regex, which can be slow for simple delimiters.
• Frequent calls to split() with large strings can cause performance bottlenecks.

Solutions

• Use String's indexOf() method to find delimiters and extract substrings manually.
• Leverage Apache Commons Lang's StringUtils.split() method which may perform better in specific scenarios.
• Consider using StringTokenizer for simple tokenization needs.

Mistake: Continuing to use String.split() without profiling for performance.

Solution: Always profile your code to identify performance bottlenecks before optimizing.

Mistake: Assuming that StringUtils.split is always faster without measuring.

Solution: Perform benchmarks to compare the performance of different splitting methods in your specific context.