title: Why I cannot use callUDF method?
body: <p>I use spark 1.6.1, and code in java. When I use callUDF(), it shows </p>
  
  <pre><code>The method callUDF(String, Column) is undefined for the type PhaseOne
  </code></pre>
  
  <p>and callUdf() does not work. My codes are as follows: </p>
  
  <pre><code>sqlContext.udf().register("stringToLong", new UDF1&lt;String, Long&gt;() {
  
          @Override
          public Long call(String arg0) throws Exception {
              // TODO Auto-generated method stub
              IPTypeConvert itc = new IPTypeConvert();
              return itc.stringtoLong(arg0);
          }
      }, DataTypes.LongType);
      DataFrame interDF = initInterDF.withColumn("interIPInt", callUDF("stringToLong", initInterDF.col("interIP")));
  </code></pre>