public class AwfulRegExpMatcher {
/** Create a matcher with the given regular expression and which will
* operate on the given input string */
public AwfulRegExpMatcher(String regExp, String inputText);

/** Retrieve the next match of the pattern against the input text,
returning the matched text if possible or null if not */
public String getNextMatch();
}

public class BadRegExpMatcher {

public BadRegExpMatcher(String regExp);

/** Attempts to match the specified regular expression against the input
text, returning the matched text if possible or null if not */
public String match(String inputText);

/** Get the next match against the input text, or return null if no match */
public String getNextMatch();
}

BadRegExpMatcher dateMatcher = new BadRegExpMatcher(...);
while (...) {
...
String headerLine = new String(myBuffer, thisHeaderStart,
thisHeaderEnd-thisHeaderStart);
String result = dateMatcher.match(headerLine);
if (result == null) { ... }
}

class BetterRegExpMatcher {
public BetterRegExpMatcher(...);

/** Provide matchers for multiple formats of input -- String,
character array, and subset of character array. Return -1 if no
match was made; return offset of match start if a match was
made. */
public int match(String inputText);
public int match(char[] inputText);
public int match(char[] inputText, int offset, int length);

/** Get the next match against the input text, if any */
public int getNextMatch();

/** If a match was made, returns the length of the match; between
the offset and the length, the caller should be able to
reconstruct the match text from the offset and length */
public int getMatchLength();

/** Convenience routine to get the match string, in the event the
caller happens to wants a String */
public String getMatchText();
}

int resultOffset = dateMatcher.match(myBuffer, thisHeaderStart,
thisHeaderEnd-thisHeaderStart);
if (resultOffset < 0) { ... }