Created
March 22, 2013 22:06
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Replace buggy Matcher.replaceAll in Android with a working version. Does not replace uncaptured group references with 'null'
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// Implementation of Matcher.replaceAll differs in Android and JDK | |
// In JDK, if a group has not been captured, it is replaced with "" | |
// In android, it is replaced with the string 'null' | |
// This is annoying. Can't really be fixed without fully encapsulating the class | |
// So, rewriting replaceAll algorithm | |
// So we'll just do backref replacement and pass it back to the original replaceAll | |
private String replaceAll(Matcher matcher, String input, String replacement) { | |
// Process substitution string to replace group references with groups | |
int cursor = 0; | |
StringBuilder result = new StringBuilder(); | |
while (cursor < replacement.length()) { | |
char nextChar = replacement.charAt(cursor); | |
if (nextChar == '\\') { | |
cursor++; | |
nextChar = replacement.charAt(cursor); | |
result.append(nextChar); | |
cursor++; | |
} else if (nextChar == '$') { | |
// Skip past $ | |
cursor++; | |
// The first number is always a group | |
int refNum = (int)replacement.charAt(cursor) - '0'; | |
if ((refNum < 0)||(refNum > 9)) | |
throw new IllegalArgumentException( | |
"Illegal group reference"); | |
cursor++; | |
// Capture the largest legal group string | |
boolean done = false; | |
while (!done) { | |
if (cursor >= replacement.length()) { | |
break; | |
} | |
int nextDigit = replacement.charAt(cursor) - '0'; | |
if ((nextDigit < 0)||(nextDigit > 9)) { // not a number | |
break; | |
} | |
int newRefNum = (refNum * 10) + nextDigit; | |
if (matcher.groupCount() < newRefNum) { | |
done = true; | |
} else { | |
refNum = newRefNum; | |
cursor++; | |
} | |
} | |
// Append group | |
if (matcher.group(refNum) != null) | |
result.append(matcher.group(refNum)); | |
} else { | |
result.append(nextChar); | |
cursor++; | |
} | |
} | |
return matcher.replaceAll(result.toString()); | |
} | |
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