split and regexps

Hello to all,

I have some code which has some perl like behavior and allows me to split a line with some separators onto a head and tail specifying an index. A negative index will start from the end of the string and will make the tail the head, handy if you're not sure on the number of columns in your list.

/**
 * will give a keyvalue pair of a line and based on the given index <br>
 * if line = 1~2~3~4~5 <br>
 * head(line,"~",0)  will give result[0]='' & result[1]='1~2~3~4~5'
 * head(line,"~",2)  will give result[0]='1~2' & result[1]='3~4~5'; 
 * head(line,"~",-2) will give result[0]='4~5' & result[1]='1~2~3';
 * to get empty value, switch key & value in calling logic.
 * @param line
 * @param separator
 * @param index
 * @return
 */
public static String [] head(String line,String separator, int index) {
String cols[] = line.split(separator);
if (Math.abs(index) > cols.length) {
throw new IllegalArgumentException("impossible to retrieve " + index + "th column of " + line);
}
int newIndex = (index >= 0 ? index : cols.length+index);
List allCols = Arrays.asList(cols);
String key = join(allCols.subList(0,newIndex), separator);
String val = join(allCols.subList(newIndex, allCols.size()), separator);
if (index < 0) {
return new String [] { val, key };
} else {
return new String [] { key, val };
}
}

public static String join (List l, String separator) {
if (l.size() == 0) {
return "";
} 
StringBuffer subResult = new StringBuffer((String) (l.get(0)));
Iterator iter = l.subList(1,l.size()).iterator();
while(iter.hasNext()) {
System.out.println("subresult " + subResult);
subResult.append(separator);
subResult.append((String) iter.next());
}
return subResult.toString();
}

All works beautiful and as expected however, the split uses regexes to match the column separators, works for ~ but not for "|", which is treated as a regex special character, I may be able to pass in "\\|" but that upsets the join feature.
So my question is: is there a way to use split only on normal "string tokens" or are there other clever ways to get divide a string in the documented way.

Thanks in advance.
jeroen.
My question is there a way to make the split none regex like

Or, if you're running JDK 5 or later,

Aah the quote functionality was something I was looking for!
good thing they put it in 5, too bad I'm bound to 1.4, I'll stick to the replace all functionality. Thanks for the lesson!
Jeroen.

In JDK 1.4, you can also use

String regex = "\\Q" + separator + "\\E";

That's actually what the later Pattern.quote() uses (unless the regex itself contains \\E internally).

Here is a JDK 1.4 version of a quote() method -- that functionally does the same thing as the JDK 1.5 version of the Pattern.quote() method.

Henry

The \Q...\E thing is a carryover from Perl; there's no good reason to use it in Java, considering how much more complicated it is to work with. I've never understood why they used it in the quote() method, but at least we don't have to deal with it.