Faster alternatives to replace method in a Java String?

Question

The fact that the replace method returns a string object rather than replacing the contents of a given string is a little obtuse (but understandable when you know that strin

Answer 1

The follow code is approx. 30 times faster if there is no match and 5 times faster if there is a match.

static String fastReplace( String str, String target, String replacement ) {
    int targetLength = target.length();
    if( targetLength == 0 ) {
        return str;
    }
    int idx2 = str.indexOf( target );
    if( idx2 < 0 ) {
        return str;
    }
    StringBuilder buffer = new StringBuilder( targetLength > replacement.length() ? str.length() : str.length() * 2 );
    int idx1 = 0;
    do {
        buffer.append( str, idx1, idx2 );
        buffer.append( replacement );
        idx1 = idx2 + targetLength;
        idx2 = str.indexOf( target, idx1 );
    } while( idx2 > 0 );
    buffer.append( str, idx1, str.length() );
    return buffer.toString();
}