class CheckAgainstNegativeOne {
public static String replaceString(String target, String oldStr, String newStr) {
if (oldStr.equals("")) {
throw new IllegalArgumentException();
}
StringBuffer result = new StringBuffer();
int lastend = 0;
int pos;
while ((pos = target.indexOf(oldStr, lastend)) != -1) {
result.append(target.substring(lastend, pos));
result.append(newStr);
lastend = pos + oldStr.length();
}
result.append(target.substring(lastend));
return result.toString();
}
}