Time for action – adding a new User Defined Function (UDF)

Let us show how to create and invoke some custom Java code via a new UDF.

1. Save the following code as City.java:

   package com.kycorsystems ;
   
   import java.util.regex.Matcher ;
   import java.util.regex.Pattern ;
   import org.apache.hadoop.hive.ql.exec.UDF ;
   import org.apache.hadoop.io.Text ;
   
   public class City extends UDF
   {
       private static Pattern pattern = Pattern.compile(
           "[a-zA-z]+?[\\. ]*[a-zA-z]+?[\\, ][^a-zA-Z]") ;
       
       public Text evaluate( final Text str)
       {
           Text result ;
           String location = str.toString().trim() ;
           Matcher matcher = pattern.matcher(location) ;
           
           if (matcher.find())
           {
               result = new Text(                 location.substring(matcher.start(), matcher.end()-2)) ;
           }
           else
           {
               result = new Text("Unknown") ;
           }        
           return result ;
       }
   }

2. Compile this file:

   $ javac -cp hive/lib/hive-exec-0.8.1.jar:hadoop...