I want to split a string into tokens.
I ripped of another Stack Overflow question - Equivalent to StringTokenizer with multiple characters delimiters, but I want to know if this can be done with only string methods (.equals(), .startsWith(), etc.). I don't want to use RegEx's, the StringTokenizer class, Patterns, Matchers or anything other than String for that matter.
For example, this is how I want to call the method
String[] delimiters = {" ", "==", "=", "+", "+=", "++", "-", "-=", "--", "/", "/=", "*", "*=", "(", ")", ";", "/**", "*/", "\t", "\n"};
String splitString[] = tokenizer(contents, delimiters);
And this is the code I ripped of the other question (I don't want to do this).
private String[] tokenizer(String string, String[] delimiters) {
// First, create a regular expression that matches the union of the
// delimiters
// Be aware that, in case of delimiters containing others (example &&
// and &),
// the longer may be before the shorter (&& should be before &) or the
// regexpr
// parser will recognize && as two &.
Arrays.sort(delimiters, new Comparator<String>() {
@Override
public int compare(String o1, String o2) {
return -o1.compareTo(o2);
}
});
// Build a string that will contain the regular expression
StringBuilder regexpr = new StringBuilder();
regexpr.append('(');
for (String delim : delimiters) { // For each delimiter
if (regexpr.length() != 1)
regexpr.append('|'); // Add union separator if needed
for (int i = 0; i < delim.length(); i++) {
// Add an escape character if the character is a regexp reserved
// char
regexpr.append('\\');
regexpr.append(delim.charAt(i));
}
}
regexpr.append(')'); // Close the union
Pattern p = Pattern.compile(regexpr.toString());
// Now, search for the tokens
List<String> res = new ArrayList<String>();
Matcher m = p.matcher(string);
int pos = 0;
while (m.find()) { // While there's a delimiter in the string
if (pos != m.start()) {
// If there's something between the current and the previous
// delimiter
// Add it to the tokens list
res.add(string.substring(pos, m.start()));
}
res.add(m.group()); // add the delimiter
pos = m.end(); // Remember end of delimiter
}
if (pos != string.length()) {
// If it remains some characters in the string after last delimiter
// Add this to the token list
res.add(string.substring(pos));
}
// Return the result
return res.toArray(new String[res.size()]);
}
public static String[] clean(final String[] v) {
List<String> list = new ArrayList<String>(Arrays.asList(v));
list.removeAll(Collections.singleton(" "));
return list.toArray(new String[list.size()]);
}
Edit: I ONLY want to use string methods charAt, equals, equalsIgnoreCase, indexOf, length, and substring
