Algorithm for joining e.g. an array of strings

Question

I have wondered for some time, what a nice, clean solution for joining an array of strings might look like. Example: I have [\"Alpha\", \"Beta\", \"Gamma\"] and want to join

Answer 1

In Java 5, with unit test:

import junit.framework.Assert;
import org.junit.Test;

public class StringUtil
{
    public static String join(String delim, String... strings)
    {
        StringBuilder builder = new StringBuilder();

        if (strings != null)
        {
            for (String str : strings)
            {
                if (builder.length() > 0)
                {
                    builder.append(delim);
                }

                builder.append(str);
            }
        }           

        return builder.toString();
    }

    @Test
    public void joinTest()
    {
        Assert.assertEquals("", StringUtil.join(", ", null));
        Assert.assertEquals("", StringUtil.join(", ", ""));
        Assert.assertEquals("", StringUtil.join(", ", new String[0]));
        Assert.assertEquals("test", StringUtil.join(", ", "test"));
        Assert.assertEquals("foo, bar", StringUtil.join(", ", "foo", "bar"));
        Assert.assertEquals("foo, bar, baz", StringUtil.join(", ", "foo", "bar", "baz"));
    }
}