JOIN METHOD

What do you do when you have an array of an Iterator full of Strings 
and
you want to turn them into a single comma-separated String? This 
becomes
an easy task by writing a generic join method.

The join method takes a collection object and a delimiting String and
puts the delimiting String in between the collection's Strings, not at 
the
beginning or end.

Here's an initial join implementation:

static public String join(Object[] strings, String delim) {
int size = strings.length;
int sizeLessOne = size - 1;
StringBuffer buffer = new StringBuffer();

for(int i=0; i<size; i++) {
buffer.append(strings[i]);
if(i != sizeLessOne) {
buffer.append(delim);
}
}

return buffer.toString();
}

The integer values, size, and sizeLessOne are worked out before the for
loop to improve speed. Their calculations are done only once and not 
for
every loop.

This method is improved slightly by estimating the initial size of the
StringBuffer. By assuming that the first element of the strings array 
is
typical, the buffer is initialized to:

StringBuffer buffer = new StringBuffer(
(strings[0].toString().length() + delim.length()) * size );

However, this is pretty vague. If memory is a concern, you probably
don't want to manually initialize the buffer, but if memory is 
abundant, then
double the buffer's initial size to play it safe.

You can also improve this method by overloading various other types of
String collection, such as java.util.Iterator and 
java.util.Enumeration.
These overloading method signatures are:

static public String join(Iterator, String);
static public String join(Enumeration, String);

Passing in a prefix and postfix provides an additional improvement, 
such
as:

static public String join(Object[] strings, String delim,
String prefix, String postfix)
{
return pre + join(strings, delim) + postfix;
}

The join method is used in the following way:

String[] strings = new String[] { "one", "two", "three" };

String joined = join(strings, ", ");

// joined is: "one, two, three";

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