Get the last three chars from any string - Java

I would consider right method from StringUtils class from Apache Commons Lang: http://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/StringUtils.html#right(java.lang.String,%20int)

It is safe. You will not get NullPointerException or StringIndexOutOfBoundsException.

Example usage:

StringUtils.right("abcdef", 3)

You can find more examples under the above link.

Here's some terse code that does the job using regex:

String last3 = str.replaceAll(".*?(.?.?.?)?$", "$1");

This code returns up to 3; if there are less than 3 it just returns the string.

This is how to do it safely without regex in one line:

String last3 = str == null || str.length() < 3 ? 
    str : str.substring(str.length() - 3);

By "safely", I mean without throwing an exception if the string is nulls or shorter than 3 characters (all the other answers are not "safe").

---

The above code is identical in effect to this code, if you prefer a more verbose, but potentially easier-to-read form:

String last3;
if (str == null || str.length() < 3) {
    last3 = str;
} else {
    last3 = str.substring(str.length() - 3);
}

Why not just String substr = word.substring(word.length() - 3)?

Update

Please make sure you check that the String is at least 3 characters long before calling substring():

if (word.length() == 3) {
  return word;
} else if (word.length() > 3) {
  return word.substring(word.length() - 3);
} else {
  // whatever is appropriate in this case
  throw new IllegalArgumentException("word has fewer than 3 characters!");
}