How to Convert a List<String> to a Joined String in Java?

How can I convert a List<String> to a single joined String in Java?

import java.util.List;
import java.util.StringJoiner;

public class StringJoinExample {
    public static void main(String[] args) {
        List<String> names = List.of("Bill", "Bob", "Steve");
        String result = String.join(" and ", names);
        System.out.println(result);
    }
}

In Java, you can convert a List<String> to a single joined String using either built-in methods such as String.join() or by implementing a custom method that utilizes StringBuilder or StringJoiner.

import java.util.List;

public class StringJoinExamples {
    public static void main(String[] args) {
        List<String> names = List.of("Bill", "Bob", "Steve");
        // Using String.join()
        String joinedString = String.join(" and ", names);
        System.out.println(joinedString);

        // Using StringJoiner
        StringJoiner joiner = new StringJoiner(" and ");
        for (String name : names) {
            joiner.add(name);
        }
        System.out.println(joiner.toString());
    }
}

Solutions

• Use the String.join() method for a simple and elegant solution.
• Utilize StringJoiner for more complex scenarios where additional formatting is needed.

Mistake: Not using the built-in String.join() method and unnecessarily implementing your own join logic.

Solution: Always prefer built-in methods for clarity and efficiency.

Mistake: Forgetting to handle null values in the list that may throw a NullPointerException.

Solution: Check for null elements in the list before joining.