Java: function for arrays like PHP's join() ?

Question

I want to join a String[] with a glue string. Is there a function for this?

Answer 1

Apache Commons Lang has a StringUtils class which has a join function which will join arrays together to make a String.

For example:

StringUtils.join(new String[] {"Hello", "World", "!"}, ", ")

Generates the following String:

Hello, World, !

Answer 2

Not in core, no. A search for "java array join string glue" will give you some code snippets on how to achieve this though.

e.g.

public static String join(Collection s, String delimiter) {
    StringBuffer buffer = new StringBuffer();
    Iterator iter = s.iterator();
    while (iter.hasNext()) {
        buffer.append(iter.next());
        if (iter.hasNext()) {
            buffer.append(delimiter);
        }
    }
    return buffer.toString();
}

Answer 3

Nothing built-in that I know of.

Apache Commons Lang has a class called StringUtils which contains many join functions.

Answer 4

But then, you could easily write such a function with about ten lines of code. Like:

String combine(String[] s, String glue)
{
  int k=s.length;
  if (k==0)
    return null;
  StringBuilder out=new StringBuilder();
  out.append(s[0]);
  for (int x=1;x<k;++x)
    out.append(glue).append(s[x]);
  return out.toString();
}

Edit: A better signature might be combine(String glue, String... s), so you could pass it either an array or a comma-separated list of strings. Whatever.

Answer 5

java.util.Arrays has an 'asList' method. Together with the java.util.List/ArrayList API this gives you all you need:;

private static String[] join(String[] array1, String[] array2) {

    List<String> list = new ArrayList<String>(Arrays.asList(array1));
    list.addAll(Arrays.asList(array2));
    return list.toArray(new String[0]);
}

Answer 6

I need to compose a variable length array of strings 10-2000. Is there a better method?