How can I join a Java List into a single String?

General Discussions
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Having worked on a few large-scale data processing projects, I’ve learned that sometimes you just can’t beat old-school efficiency.

If you’re handling very large lists where performance is critical, manual construction using StringBuilder is still the most efficient java list join technique.

import java.util.List;

public class Main {
    public static void main(String[] args) {
        List<String> names = List.of("Bill", "Bob", "Steve");
        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < names.size(); i++) {
            sb.append(names.get(i));
            if (i < names.size() - 1) {
                sb.append(" and ");
            }
        }

        System.out.println(sb.toString()); // Output: Bill and Bob and Steve
    }
}

:white_check_mark: Why consider this?

  • Gives you complete control over how the string is built.
  • Highly efficient for very large datasets where even minor optimizations matter.
  • Avoids creating unnecessary intermediate strings.

That being said, for everyday cases, String.join() or Collectors.joining() should cover most of your java list join scenarios beautifully — but it’s always good to know when to go the manual route!