Best way to concatenate List of String objects? [duplicate]

Question

Use one of the the StringUtils.join methods in Apache Commons Lang.

import org.apache.commons.lang3.StringUtils;

String result = StringUtils.join(list, ", ");

If you are fortunate enough to be using Java 8, then it's even easier...just use String.join

String result = String.join(", ", list);

Using Java 8+

String str = list.stream().collect(Collectors.joining())

or even

String str = String.join("", list);

Your approach is dependent on Java's ArrayList#toString() implementation.

While the implementation is documented in the Java API and very unlikely to change, there's a chance it could. It's far more reliable to implement this yourself (loops, StringBuilders, recursion whatever you like better).

Sure this approach may seem "neater" or more "too sweet" or "money" but it is, in my opinion, a worse approach.

A variation on codefin's answer

public static String concatStringsWSep(Iterable<String> strings, String separator) {
    StringBuilder sb = new StringBuilder();
    String sep = "";
    for(String s: strings) {
        sb.append(sep).append(s);
        sep = separator;
    }
    return sb.toString();                           
}

If you are developing for Android, there is TextUtils.join provided by the SDK.

This is the most elegant and clean way I've found so far:

list.stream().collect(Collectors.joining(delimiter));

Guava is a pretty neat library from Google:

Joiner joiner = Joiner.on(", ");
joiner.join(sList);