guava/src/com/google/common/base/Strings.java
public static String commonSuffix(CharSequence a, CharSequence b) {
    checkNotNull(a);
    checkNotNull(b);

    int maxSuffixLength = Math.min(a.length(), b.length());
    int s = 0;
    while (s < maxSuffixLength && a.charAt(a.length() - s - 1) == b.charAt(b.length() - s - 1)) {
      s++;
    }
    if (validSurrogatePairAt(a, a.length() - s - 1)
        || validSurrogatePairAt(b, b.length() - s - 1)) {
      s--;
    }
    return a.subSequence(a.length() - s, a.length()).toString();
  }
public static String commonSuffix(CharSequence a, CharSequence b) {
    checkNotNull(a);
    checkNotNull(b);

    int maxSuffixLength = Math.min(a.length(), b.length());
    int s = 0;
    while (s < maxSuffixLength && a.charAt(a.length() - s - 1) == b.charAt(b.length() - s - 1)) {
      s++;
    }
    if (validSurrogatePairAt(a, a.length() - s - 1)
        || validSurrogatePairAt(b, b.length() - s - 1)) {
      s--;
    }
    return a.subSequence(a.length() - s, a.length()).toString();
  }
public static String commonSuffix ( CharSequence a , CharSequence b ) { checkNotNull ( a ) ; checkNotNull ( b ) ; int maxSuffixLength = Math . min ( a . length ( ) , b . length ( ) ) ; int s = 0 ; while ( s < maxSuffixLength && a . charAt ( a . length ( ) - s - 1 ) == b . charAt ( b . length ( ) - s - 1 ) ) { s ++ ; } if ( validSurrogatePairAt ( a , a . length ( ) - s - 1 ) || validSurrogatePairAt ( b , b . length ( ) - s - 1 ) ) { s -- ; } return a . subSequence ( a . length ( ) - s , a . length ( ) ) . toString ( ) ; }
Returns the longest string {@code suffix} such that {@code a.toString().endsWith(suffix) &&
b.toString().endsWith(suffix)}, taking care not to split surrogate pairs. If {@code a} and
{@code b} have no common suffix, returns the empty string.

@since 11.0
Returns the longest string { @code suffix } such that { @code a . toString () . endsWith ( suffix ) && b . toString () . endsWith ( suffix ) } taking care not to split surrogate pairs . If { @code a } and { @code b } have no common suffix returns the empty string .