import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.classification.InterfaceStability; @InterfaceAudience.Public @InterfaceStability.Stable public class StringUtil { /** * */ @InterfaceStability.Evolving public static String reverseString(String str) { return new StringBuilder(str).reverse().toString(); } /** * */ @InterfaceStability.Unstable public static boolean isStringEmpty(String str) { } }